Novel 1q22-q23.1 duplication in a patient with lambdoid and metopic craniosynostosis, muscular hypotonia, and psychomotor retardation

Novel 1q22-q23.1 duplication in a patient with lambdoid and metopic craniosynostosis, muscular... Craniosynostosis (CS) refers to the group of craniofacial malformations characterized by the premature closure of one or more cranial sutures. The disorder is clinically and genetically heterogeneous and occurs usually as an isolated trait, but can also be syndromic. In 30–60% of patients, CS is caused by known genetic factors; however, in the rest of the cases, causative molecular lesions remain unknown. In this paper, we report on a sporadic male patient affected by complex CS (metopic and unilateral lambdoid synostosis), muscular hypotonia, psychomotor retardation, and facial dysmorphism. Since a subset of CS results from submicroscopic chromosomal aberrations, we performed array comparative genomic hybridization (array CGH) in order to identify possibly causative copy-number variation. Array CGH followed by breakpoint sequencing revealed a previously unre- ported de novo 1.26 Mb duplication at chromosome 1q22-q23.1 that encompassed two genes involved in osteoblast differenti- ation: BGLAP, encoding osteocalcin (OCN), and LMNA, encoding lamin A/C. OCN is a major component of bone extracellular matrix and a marker of osteogenesis, whereas mutations in LMNA cause several genetic disorders called laminopathies, including mandibuloacral dysostosis (MAD) that manifests with low bone mass, severe bone deformities, and delayed closure of the cranial sutures. Since LMNA and BGLAP overexpression promote osteoblast differentiation and calcification, phenotype of our patient may result from misexpression of the genes. Based on our findings, we hypothesize that both LMNA and BGLAP may be implicated in the pathogenesis of CS in humans. However, further studies are needed to establish the exact pathomechanism underlying development of this defect. . . . . Keywords Craniosynostosis Psychomotor retardation 1q22-q23.1 duplication LMNA BGLAP Introduction et al. 1995). Premature fusion of one or more sutures leads to the distortions of the skull shape and early closure of the Craniosynostosis (CS), the premature fusion of the cranial fontanelles, which in approximately 50% of cases results in sutures, occurs in about 1:2000 to 1:2500 live born infants raised intracranial pressure. Consequently, increased risk for and represents one of the most common congenital craniofa- cortex lesion with intellectual disability or visual and hearing cial malformation (Cohen 1979; French et al. 1990;Lajeunie impairment is observed (Renier et al. 1982; Morriss-Kay and Wilkie 2005). CS is a clinically and genetically heterogeneous group of Communicated by: Michal Witt disorders that may either occur in rare syndromic forms or, more frequently, as nonsyndromic isolated trait (Wilkie et al. * Anna Sowińska-Seidler 2007). The vast majority of CS patients are sporadic; however, asowinskaseidler@gmail.com 10–15% cases show familial recurrence (Cohen 2002). * Aleksander Jamsheer Syndromic forms comprise over 180 different genetic condi- jamsheer@wp.pl tions, in which CS is associated with a broad spectrum of 1 clinical symptoms, including skeletal defects, digital Department of Medical Genetics, Poznan University of Medical malformations, facial dysmorphism, cardiac and genitouri- Sciences, Rokietnicka 8 Street, 60-806 Poznan, Poland 2 nary defects or other organ abnormalities (Gleeson et al. Department of Radiotherapy, The Maria Skłodowska Curie 2006; OMIM). The most commonly recognized CS syn- Memorial Cancer Centre and Institute of Oncology, Gliwice Branch, 44-101 Gliwice, Poland dromes that have well-defined clinical phenotype include 282 J Appl Genetics (2018) 59:281–289 Apert (MIM 101200), Crouzon (MIM 123500), Pfeiffer visualized by the SignalMap software (NimbleGen Systems (MIM 101600), Muenke (MIM 602849), Saethre-Chotzen Inc.). The aberrant genomic locus was visualized and ana- (MIM 101400), Jackson-Weiss (MIM 123150), and Antley- lyzed in Cytoscape v3.3.0 (Shannon et al. 2003). Bixler (MIM 207410) syndromes (Kutkowska-Kazmierczak et al. 2018). The underlying genetic cause of these disorders Quantitative real-time PCR (qPCR) involves mutations in the FGFR1, FGFR2, FGFR3,and TWIST1 genes (OMIM). Other less frequent disorders result We performed a quantitative real-time PCR (qPCR) in the from different mutations in the TCF12, EFNB1, MSX2, ALX3, index patient and his parents in order to confirm array CGH GLI3, IL11RA,and ERF genes (Jabs et al. 1993; Twigg et al. results and to show the inheritance pattern of the identified 2009, 2013; Hurst et al. 2011; Keupp et al. 2013;Sharmaetal. duplication using ViiA™ 7 Real-Time thermal cycler 2013; Kutkowska-Kazmierczak et al. 2018). Conversely, little (Applied Biosystems). TheqPCRassay wasdesignedtodeter- is known about genetic etiology of isolated CS and in the mine the number of copies within the 1q22-q23.1 locus. Three majority of cases the underlying molecular defect remains primer pairs were used to amplify the region of duplication unidentified. Nonetheless, a couple of studies have demon- and two primer pairs for the 5′ and 3′ flanking regions. strated that complex forms of the disease result from chromo- Moreover, we used qPCR assay to narrow down the duplica- somal microaberrations referred to as copy number variations tion region prior to breakpoint sequencing. This was carried (CNVs), which may account for up to 10–15% of CS (Stratton out with the set of eight primer pairs. All reactions were run in et al. 1986; Eshel et al. 2002; Wilkieetal. 2010; Massalska et triplicate. The results were normalized to albumin (ALB)and al. 2014). Lambdoid CS, accounting only for 2–4% of the the copy number in each of the analyzed regions was deter- cases, represents its rarest form with entirely unknown molec- mined by means of comparative DDCt method using healthy ular origin. The pathomechanism of CNVs could be explained control DNA as a calibrator. In order to assure reliability of the by either gene dosage effect leading to overexpression or assay, we performed sex determination of samples in reference haploinsufficiency of a gene/genes or by cis-regulatory effect to factor VIII (F8) located on X chromosome. Reaction con- that leads to misexpression of a target gene resulting from ditions and primer sequences are available upon request. change of its regulatory landscape (Klopocki et al. 2011). In this paper, we describe a sporadic male proband affected Breakpoint sequencing by complex CS, composed of metopic and lambdoid synosto- sis, muscular hypotonia, psychomotor retardation, and facial The exact breakpoints of the rearrangement were determined dysmorphism, resulting from a previously unreported de novo with the use of polymerase chain reaction (PCR) with primers 1.26 Mb duplication at chromosome 1q22-q23.1, designed to amplify the DNA fragment spanning the 3′ and 5′ encompassing two genes involved in osteoblastogenesis: ends of the duplication at chromosome 1q22-q23.1. BGLAP encoding osteocalcin (OCN) and LMNA encoding Sequencing of the PCR product was carried out using dye- lamin A/C. To our knowledge, this is the first genetic abnor- terminator chemistry (kit v.3, ABI 3130XL) and run on auto- mality found in a patient presenting with lambdoid CS and the mated sequencer ABI Prism 3700 DNA Analyzer (Applied first report concerning the putative contribution of a CNV Biosystems). Reaction conditions and primer sequences are affecting BGLAP and LMNA genes to the premature closure available upon request. of the cranial sutures. BGLAP and LMNA genes relative expression Methods The relative expression level of both BGLAP and LMNA genes in blood was carried out in the proband and five controls Array comparative genomic hybridization (array CGH) by means of comparative DDCt method. Total RNA was ex- tracted from whole blood with the use of PAXgene Blood Genomic DNA of the index patient and his parents was ex- RNA System (PreAnalytiX), according to standard protocols tracted from peripheral blood leukocytes using standard pro- provided by the manufacturers. One microgram of total RNA tocols. Array comparative genomic hybridization (array was reversely transcribed using random hexamer primer CGH) was performed with the use of high resolution 1.4 M (RevertAid First Strand cDNA Synthesis Kit; ThermoFisher NimbleGen oligonucleotide array CGH (Roche NimbleGen) Scientific), according to standard protocols provided by the according to standard protocols provided by the manufac- manufacturers. Quantifications of the target and reference turers. Analysis was carried out with Deva software (Roche gene in the proband and controls was carried out using NimbleGen). Analysis settings were as follows: aberration al- ViiA™ 7 Real-Time thermal cycler (Applied Biosystems). gorithm, ADM-2; threshold, 6.0; window size, 0.2 Mb; filter, For each cDNA sample, all reactions were run in triplicate. five probes, log2ratio = 0.29. The genomic profile was Relative expression of BGLAP and LMNA in the proband was J Appl Genetics (2018) 59:281–289 283 normalized to TBP reference transcript and to mean value of (Fig. 2a, b), hypotelorism (Fig. 2b), as well as digitate five controls. Reaction conditions and primer sequences are impressions most marked in the bone structures of the right available upon request. occipito-parietal region (Fig. 2c). Upon neurological as- sessment at the age of 7 months, the patient presented with Serum levels of bone turnover markers psychomotor retardation with global development that amounted to 3 months of age. Conventional chromosomal Biochemical analyses of serum levels of alkaline phosphatase, analysis performed on peripheral blood lymphocytes with inorganic phosphate, and total calcium were performed with a resolution of 550 bands per haploid genome showed nor- the use of standard laboratory methods. The serum osteocalcin mal male karyotype (46,XY). and intact parathyroid hormone levels were determined using chemiluminescence immunoassay (CLIA) (LIAISON XL; Serum levels of bone turnover markers Diasorin and ADIVIA Centaur XP Immunoassay System; Siemens respectively). The results were compared to the lab- Osteocalcin serum level (224 ng/ml) was 3.4-fold higher as oratory reference ranges. compared to the reference range (4.6–65.4 ng/ml). The serum concentrations of alkaline phosphatase (301 U/L), inorganic phosphate (4.6 mg/dl), and total calcium (10.7 mg/dl) were Results within normal ranges as compared to the reference values (142–335 U/L, 3.3–5.6 mg/dl, 8.8–10.8 mg/dl, respectively), Clinical report while intact parathyroid hormone was slightly lowered (12.6 pg/ml) in comparison to the reference range (18.5– The proband, a 5-month-old male patient of Polish ethnic- 88.0 pg/ml). ity, was born by spontaneous delivery after uneventful pregnancy (G1P1) at 38 weeks of gestation to a non- consanguineous and healthy 32-year-old mother and a Array comparative genomic hybridization (array CGH) 33-year-old father. At birth, his weight was 2900 g (3rd– 10th percentile), length 57 cm (75th–90th percentile), head Array CGH detected a previously unreported duplication at circumference 30 cm (below 3rd percentile), and Apgar chromosome 1q22-q23.1 (chr1:155927620–157198170; score was 10. Physical examination after birth showed hg19), encompassing 42 protein coding genes, including trigonocephaly and associated facial dysmorphism. BGLAP, encoding osteocalcin, and LMNA, encoding lamin Abdominal and transfontanellar ultrasounds performed af- A/C (Fig. 3a). ter birth were unremarkable. Hearing tests and ophthalmo- logic examinations were carried out during the first week after birth and repeated regularly throughout the first Quantitative real-time PCR (qPCR) and breakpoint months of life and were normal. The boy was referred to analysis the genetic clinic for diagnosis and first investigated by a clinical geneticist at the age of 5 months. Upon examina- qPCR confirmed the 1q22-q23.1 duplication in the proband tion, he presented with global developmental delay, severe and excluded its presence in both unaffected parents. muscular hypotonia, and craniofacial dysmorphic features Subsequent rounds of qPCR narrowed down the region of comprising prominent metopic ridge, trigonocephaly, high- duplication and allowed for the design of primers for arched palate, prominent occiput, hypotelorism, shallow breakpoint sequencing. Sequencing of the breakpoints re- orbits, and low-set, posteriorly rotated ears (Fig. 1a, b). vealed an insertion of four nucleotides (TTCT) at one of the His body weight was 5.5 kg (below 3rd percentile). CT breakpoints. The exact size of the duplication was scan of the head performed at the age of 7 months showed 1,255,998 bp (chr1:155931219–157187216; hg19). premature fusion of the metopic suture along with unilat- Breakpoint sequencing results were shown in Fig. 3b. eral right-sided lambdoid craniosynostosis (Fig. 1c), as well as thin and hypoplastic corpus callosum, morpholog- ical abnormalities of the median brain structures, including BGLAP and LMNA relative expression abnormal development of the white matter (Fig. 1d), and Chiari malformation (Fig. 1e). 3D modeling of the patient’s The analysis of BGLAP and LMNA relative expression per- skull performed with the use of RadiAnt DICOM Viewer formed in blood samples of the proband and five controls showed posterior plagiocephaly (Fig. 2a) due to premature- revealed 1.8-fold increase of BGLAP expression and 1.4-fold ly closed right lambdoid suture (Fig. 2c) and prominent increase of LMNA expression in the proband in reference to metopic ridge due to premature metopic synostosis the mean value of controls (Fig. 4). 284 J Appl Genetics (2018) 59:281–289 Fig. 1 Facial view of the proband showing craniofacial abnormalities comprising a trigonocephaly with prominent metopic ridge, shallow orbits, proptosis, and hypotelorism and b flat facial profile, prominent occiput, and low-set, posteriorly rotated ears. c CTscan of the head showing premature synostosis of the metopic suture (trigonocephaly) and right lambdoid suture (indicated in red). MS—metopic suture, CS— coronal suture, LS—lambdoid suture. d CT scan of the head (sagittal view) showing thin and hypoplastic corpus callosum (marked with a white arrow) as well as morphological abnormal- ities of the median brain struc- tures, including abnormal devel- opment of the white matter (marked with a yellow arrow). e CT scan of the head (coronal sec- tion) showing Chiari malforma- tion; white arrow indicates downward displacement of the right cerebellar tonsil through the foramen magnum Discussion RUNX2 duplications (Mefford et al. 2010), and MSX2 du- plications (Kariminejad et al. 2009). The fusion of cranial Genetic changes underlying most of the CS types, especial- sutures is orchestrated by an interplay between collagen ly other than coronal synostosis, remain largely unknown. fibers and mesenchymal cells that differentiate into osteo- A small proportion of metopic synostosis is caused by blasts, osteoclasts and osteocytes upon mechanical stress. 9p22 deletions and point mutations in FREM1 (Vissers et The molecular origin of CS has been linked to mutations in al. 2011). However, most of the cases remain undiagnosed genes encoding osteoblastogenic proteins that trigger the at a molecular level. Complex CS may rarely result from premature osteogenesis in cranial sutures via different mo- mutations in a recently discovered gene ERF, which en- lecular pathways (Katsianou et al. 2016). codes for a transcription factor (Twigg et al. 2013). In this paper, we describe a previously unreported de novo Furthermore, complex forms of the disease may be also 1.26 Mb duplication at chromosome 1q22-q23.1 identified in caused by chromosomal rearrangements, including small a sporadic male proband presenting with complex CS submicroscopic segmental aberrations referred to as copy (metopic and right-sided lambdoid synostosis), muscular hy- number variations (CNVs), which are estimated to account potonia, psychomotor retardation, and facial dysmorphism. for 10–15% of CS (Stratton et al. 1986; Eshel et al. 2002; The duplication encompasses 42 protein coding genes, includ- Wilkie et al. 2010; Massalska et al. 2014). Several interest- ing BGLAP and LMNA, both implicated in osteoblast differ- ing examples of CNVs resulting in craniosynostosis in- entiation, which are most probably involved in the pathogen- clude IHH regulatory mutations (Klopocki et al. 2011), esis of the clinical phenotype observed in our patient. J Appl Genetics (2018) 59:281–289 285 Fig. 2 3D modeling of the patient’s skull. a Aerial view presenting section presenting prematurely closed right lambdoid suture with digitate asymmetric posterior plagiocephaly and prominent metopic ridge (black impressions (indicated by black arrows) most marked in the right arrow) due to premature metopic synostosis. b Frontal view showing occipito-parietal region prominent metopic ridge (black arrow) and hypotelorism. c Horizontal BGLAP encodes osteocalcin (OCN), the most abundant required as molecular switches for Bglap expression. The non-collagen component of bone extracellular matrix. The gene’s activity during osteogenesis reflects the stages of oste- protein promotes matrix mineralization by high binding prop- oblast differentiation. Bglap is transcriptionally repressed in erties for calcium and hydroxyapatite, thus having a pivotal proliferating cells by Msx2, whereas in mature osteoblasts role in osteogenesis (Kruse and Kracht 1986;Sandberg etal. Dlx3, Dlx5, and Runx2 are recruited to initiate the gene tran- 1993;McGuigan et al. 2010). There are several signal trans- scription. Thus, OCN is considered to be a major marker of duction cascades involved in osteogenesis during cranial su- mature osteoblasts (Hassan et al. 2004). Of note, studies on rat ture development, including the MAPK/ERK pathway (acti- models demonstrated that Bglap expression level (as well as vated by FGFRs), SMAD signaling network, and Wnt/β- other bone-associated extracellular matrix molecules) is up- catenin pathway. Hyperactivation of these pathways results regulated in calvarial dura matter, directly underlying fusion in premature closure of sutures leading to craniofacial abnor- of sutures (Greenwald et al. 2000). To date, genetic abnormal- malities (Katsianou et al. 2016). Two major downstream target ities directly affecting the BGLAP have not been reported to proteins for these signaling cascades, Runx2 and Msx2, are cause premature closure of sutures. However, several studies Fig. 3 a Interstitial duplication in the index at 1q22-q23.1 encompassing (chr1:155931219–157187216; hg19), and an insertion of four LMNA and BGLAP genes, identified by means of array CGH (Roche nucleotides (TTCT) at one of the breakpoints NimbleGen). b Breakpoint sequencing results: a 1.26 Mb duplication 286 J Appl Genetics (2018) 59:281–289 1999; Maraldi et al. 2006). Based on clinical features, laminopathies could be organized into four groups: muscle disorders, lipodystrophies, neuropathies, and accelerated ag- ing disorders. The explanation of pleiotropic effect of various mutations in a single gene is attributed to the differences in the molecular mechanisms via which the variants affect the pro- tein function. These include abnormal protein structure, alter- ation of its charge, or failure of the post-transcriptional pro- cessing of LMNA. Unprocessed protein is accumulated in the cells and incorporated into the nuclei where it interferes with the nuclear integrity, resulting in destabilization of the nucleus structure (Worman and Bonne 2007). The pathomechanism underlying a variety of phenotypes Fig. 4 Relative expression levels of BGLAP and LMNA genes in blood found in human laminopathies has been investigated in both in samples of the proband and controls indicating 1.8-fold increase of vitro and in vivo studies. The features associated with LMNA BGLAP expression and 1.4-fold increase of LMNA expression in the loss-of function mutations arise from primarily affected MSCs proband compared to the mean value of five healthy controls. Error and include reduction in muscle mass, defects of bone forma- bars represent standard deviation tion, and craniofacial symptoms, such as delayed closure of sutures as seen in mandibuloacral dysplasia (MAD) and have determined how mutations in key elements of the Hutchinson-Gilford progeria (Novelli et al. 2002;De aforementioned signal transduction pathways alter the Sandre-Giovannoli et al. 2003;Shen et al. 2003;Yangetal. BGLAP expression pattern in osteoblast derived from 2006; Kim et al. 2011). Studies using the spontaneous Lmna fused sutures. According to these reports, the gene expres- mutation (Dhe) mouse, which serves as a naturally occurring sion was elevated in patients with Apert syndrome, as well animal model for laminopathies, show that the cranial suture as in mice harboring Fgfr1 Pro250Arg Pfeiffer syndrome tissue that fails to fuse exhibits abnormal nuclear morphology, mutation, thus confirming the direct correlation between hypomineralization, and low level of collagen I and III expres- the increased level of osteogenic proteins and the patho- sion (Odgren et al. 2010). Furthermore, the important role of logical ossification of sutures in both human and mice LMNA in the formation of mineralized matrix has been dem- (Lemonnier et al. 2000, 2001; Zhou et al. 2000). These onstrated in vitro using human osteoblasts and MSCs. Lamin findings are consistent with the results of our study in A/C knock-down in these cell lines resulted in impaired os- which we observed an elevated blood expression of teoblastogenesis, enhanced osteoclast formation, and in- BGLAP and increased serum osteocalcin level in the pro- creased adipogenesis, which was associated with reduced band, probably due to the identified duplication. Of note, RUNX2, BGLAP,and ALP expression levels, as well as the the serum alkaline phosphatase (ALP) level was within a impaired RUNX2 nuclear binding activity (Akter et al. 2009; normal range. Based on our observations, we hypothesize Rauner et al. 2009). Consistent with these data, studies using −/− that the CNV results in the general overexpression of Lmna mice showed decreased bone volume and muscular BGLAP that may have occurred also locally during osteo- atrophy that occurred concomitantly with increased bone mar- genesis in fusing cranial sutures, leading to the craniosyn- row and inter-myofiber fat infiltration, in the 4-week-old mu- ostosisobservedinour patient. tants as compared to controls (Tong et al. 2011). Since pro- Another interesting gene included in the duplication found gressive muscle weakness is a principal sign in a number of in our proband was LMNA. LMNA encodes lamin A/C, a laminopathies, including Emery-Dreifuss muscular dystro- nuclear intermediate filament protein that plays a major role phy, limb-girdle muscular dystrophy, and Charcot-Marie- −/− in the structural organization of the nucleus and regulation of Tooth type 2B1 and has been reported in the Lmna mice, gene expression via interaction with signaling molecules and muscular hypotonia observed in our patient may also be at- transcription factors (Aebi et al. 1986). The role of lamin A/C tributed to the abnormal gene expression and functioning of in osteoblastogenesis is associated with its potential to control LMNA. In addition, psychomotor retardation manifested by the fate of mesenchymal stem cells (MSCs), which may dif- our proband may result not only from hypotonia and muscular ferentiate into either osteoblast or adipocytes. Different muta- weakness, but also from the impediment of the growth of the tions in LMNA disrupt the integrity of the nuclear envelope, patient’s brain. This is often seen in complex forms of CS, mostly in the cells subjected to mechanical stress, leading to a even in cases where there is no overt evidence for increased group of disorders known as laminopathies (Manilal et al. intracranial pressure. J Appl Genetics (2018) 59:281–289 287 Ethical approval All procedures performed in studies involving hu- Interestingly, LMNA gene dosage may be also implicated man participants were in accordance with the ethical standards of the in the pathogenesis of CS, as its overexpression correlates institutional and/or national research committee and with the 1964 with an elevated level of osteogenic factors including Helsinki Declaration and its later amendments or comparable ethical RUNX2 and OCN (Bermeo et al. 2015; Tsukune et al. standards. Ethics approval was granted by the Institutional Review Board of Poznan University of Medical Sciences. 2017). Consistently, we demonstrated that LMNA expres- sion measured in peripheral blood of the index patient was Conflict of interest The authors declare no conflict of interest. elevated by 1.4-fold in comparison with healthy controls. This slight overexpression may contribute to craniosynos- Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http:// tosis but is rather inconsistent with muscular hypotonia, as creativecommons.org/licenses/by/4.0/), which permits unrestricted use, this feature is related to decreased level of LMNA (Tong et distribution, and reproduction in any medium, provided you give appro- al. 2011). Considering a possibility that dosage imbalance priate credit to the original author(s) and the source, provide a link to the of other than LMNA and BGLAP genes could contribute to Creative Commons license, and indicate if changes were made. the observed phenotype, we analyzed the predicted effect of haploinsufficiency (HI) of all protein-coding genes includ- ed in the duplication. Out of seven genes with a high (< 10%) or moderate (< 25%) HI score (NES, CCT3, References MEF2D, LAMTOR2, ETV3, SSR2, NTRK1), none of them have been linked to craniosynostosis (Huang et al. 2010). A Aebi U, Cohn J, Buhle L, Gerace L (1986) The nuclear lamina is a partly overlapping deletion in the 1q22-q23.1 region has meshwork of intermediate-type filaments. Nature 323:560–564. https://doi.org/10.1038/323560a0 been recently described in a patient presenting with intel- Akter R, Rivas D, Geneau G et al (2009) Effect of Lamin A/C knock- lectual disability and multiple congenital anomalies, and down on osteoblast differentiation and function. J Bone Min Res 24: two of the HI genes, NES and MAF2D,wereshowntobe 283–293. https://doi.org/10.1359/jbmr.081010 necessary for normal neuron development in mice Aleksiuniene B, Preiksaitiene E, Morkuniene A et al (2018) A de (Ikeshima et al. 1995;Parket al. 2010; Aleksiuniene et al. novo 1q22q23.1 interstitial microdeletion in a girl with intel- lectual disability and multiple congenital anomalies including 2018). Therefore, dosage imbalance could possibly contrib- congenital heart defect. 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Exp Cell Res 313:2121–2133. https://doi.org/10. 1016/j.yexcr.2007.03.028 http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Applied Genetics Springer Journals

Novel 1q22-q23.1 duplication in a patient with lambdoid and metopic craniosynostosis, muscular hypotonia, and psychomotor retardation

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Life Sciences; Plant Genetics and Genomics; Human Genetics; Animal Genetics and Genomics; Microbial Genetics and Genomics
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Abstract

Craniosynostosis (CS) refers to the group of craniofacial malformations characterized by the premature closure of one or more cranial sutures. The disorder is clinically and genetically heterogeneous and occurs usually as an isolated trait, but can also be syndromic. In 30–60% of patients, CS is caused by known genetic factors; however, in the rest of the cases, causative molecular lesions remain unknown. In this paper, we report on a sporadic male patient affected by complex CS (metopic and unilateral lambdoid synostosis), muscular hypotonia, psychomotor retardation, and facial dysmorphism. Since a subset of CS results from submicroscopic chromosomal aberrations, we performed array comparative genomic hybridization (array CGH) in order to identify possibly causative copy-number variation. Array CGH followed by breakpoint sequencing revealed a previously unre- ported de novo 1.26 Mb duplication at chromosome 1q22-q23.1 that encompassed two genes involved in osteoblast differenti- ation: BGLAP, encoding osteocalcin (OCN), and LMNA, encoding lamin A/C. OCN is a major component of bone extracellular matrix and a marker of osteogenesis, whereas mutations in LMNA cause several genetic disorders called laminopathies, including mandibuloacral dysostosis (MAD) that manifests with low bone mass, severe bone deformities, and delayed closure of the cranial sutures. Since LMNA and BGLAP overexpression promote osteoblast differentiation and calcification, phenotype of our patient may result from misexpression of the genes. Based on our findings, we hypothesize that both LMNA and BGLAP may be implicated in the pathogenesis of CS in humans. However, further studies are needed to establish the exact pathomechanism underlying development of this defect. . . . . Keywords Craniosynostosis Psychomotor retardation 1q22-q23.1 duplication LMNA BGLAP Introduction et al. 1995). Premature fusion of one or more sutures leads to the distortions of the skull shape and early closure of the Craniosynostosis (CS), the premature fusion of the cranial fontanelles, which in approximately 50% of cases results in sutures, occurs in about 1:2000 to 1:2500 live born infants raised intracranial pressure. Consequently, increased risk for and represents one of the most common congenital craniofa- cortex lesion with intellectual disability or visual and hearing cial malformation (Cohen 1979; French et al. 1990;Lajeunie impairment is observed (Renier et al. 1982; Morriss-Kay and Wilkie 2005). CS is a clinically and genetically heterogeneous group of Communicated by: Michal Witt disorders that may either occur in rare syndromic forms or, more frequently, as nonsyndromic isolated trait (Wilkie et al. * Anna Sowińska-Seidler 2007). The vast majority of CS patients are sporadic; however, asowinskaseidler@gmail.com 10–15% cases show familial recurrence (Cohen 2002). * Aleksander Jamsheer Syndromic forms comprise over 180 different genetic condi- jamsheer@wp.pl tions, in which CS is associated with a broad spectrum of 1 clinical symptoms, including skeletal defects, digital Department of Medical Genetics, Poznan University of Medical malformations, facial dysmorphism, cardiac and genitouri- Sciences, Rokietnicka 8 Street, 60-806 Poznan, Poland 2 nary defects or other organ abnormalities (Gleeson et al. Department of Radiotherapy, The Maria Skłodowska Curie 2006; OMIM). The most commonly recognized CS syn- Memorial Cancer Centre and Institute of Oncology, Gliwice Branch, 44-101 Gliwice, Poland dromes that have well-defined clinical phenotype include 282 J Appl Genetics (2018) 59:281–289 Apert (MIM 101200), Crouzon (MIM 123500), Pfeiffer visualized by the SignalMap software (NimbleGen Systems (MIM 101600), Muenke (MIM 602849), Saethre-Chotzen Inc.). The aberrant genomic locus was visualized and ana- (MIM 101400), Jackson-Weiss (MIM 123150), and Antley- lyzed in Cytoscape v3.3.0 (Shannon et al. 2003). Bixler (MIM 207410) syndromes (Kutkowska-Kazmierczak et al. 2018). The underlying genetic cause of these disorders Quantitative real-time PCR (qPCR) involves mutations in the FGFR1, FGFR2, FGFR3,and TWIST1 genes (OMIM). Other less frequent disorders result We performed a quantitative real-time PCR (qPCR) in the from different mutations in the TCF12, EFNB1, MSX2, ALX3, index patient and his parents in order to confirm array CGH GLI3, IL11RA,and ERF genes (Jabs et al. 1993; Twigg et al. results and to show the inheritance pattern of the identified 2009, 2013; Hurst et al. 2011; Keupp et al. 2013;Sharmaetal. duplication using ViiA™ 7 Real-Time thermal cycler 2013; Kutkowska-Kazmierczak et al. 2018). Conversely, little (Applied Biosystems). TheqPCRassay wasdesignedtodeter- is known about genetic etiology of isolated CS and in the mine the number of copies within the 1q22-q23.1 locus. Three majority of cases the underlying molecular defect remains primer pairs were used to amplify the region of duplication unidentified. Nonetheless, a couple of studies have demon- and two primer pairs for the 5′ and 3′ flanking regions. strated that complex forms of the disease result from chromo- Moreover, we used qPCR assay to narrow down the duplica- somal microaberrations referred to as copy number variations tion region prior to breakpoint sequencing. This was carried (CNVs), which may account for up to 10–15% of CS (Stratton out with the set of eight primer pairs. All reactions were run in et al. 1986; Eshel et al. 2002; Wilkieetal. 2010; Massalska et triplicate. The results were normalized to albumin (ALB)and al. 2014). Lambdoid CS, accounting only for 2–4% of the the copy number in each of the analyzed regions was deter- cases, represents its rarest form with entirely unknown molec- mined by means of comparative DDCt method using healthy ular origin. The pathomechanism of CNVs could be explained control DNA as a calibrator. In order to assure reliability of the by either gene dosage effect leading to overexpression or assay, we performed sex determination of samples in reference haploinsufficiency of a gene/genes or by cis-regulatory effect to factor VIII (F8) located on X chromosome. Reaction con- that leads to misexpression of a target gene resulting from ditions and primer sequences are available upon request. change of its regulatory landscape (Klopocki et al. 2011). In this paper, we describe a sporadic male proband affected Breakpoint sequencing by complex CS, composed of metopic and lambdoid synosto- sis, muscular hypotonia, psychomotor retardation, and facial The exact breakpoints of the rearrangement were determined dysmorphism, resulting from a previously unreported de novo with the use of polymerase chain reaction (PCR) with primers 1.26 Mb duplication at chromosome 1q22-q23.1, designed to amplify the DNA fragment spanning the 3′ and 5′ encompassing two genes involved in osteoblastogenesis: ends of the duplication at chromosome 1q22-q23.1. BGLAP encoding osteocalcin (OCN) and LMNA encoding Sequencing of the PCR product was carried out using dye- lamin A/C. To our knowledge, this is the first genetic abnor- terminator chemistry (kit v.3, ABI 3130XL) and run on auto- mality found in a patient presenting with lambdoid CS and the mated sequencer ABI Prism 3700 DNA Analyzer (Applied first report concerning the putative contribution of a CNV Biosystems). Reaction conditions and primer sequences are affecting BGLAP and LMNA genes to the premature closure available upon request. of the cranial sutures. BGLAP and LMNA genes relative expression Methods The relative expression level of both BGLAP and LMNA genes in blood was carried out in the proband and five controls Array comparative genomic hybridization (array CGH) by means of comparative DDCt method. Total RNA was ex- tracted from whole blood with the use of PAXgene Blood Genomic DNA of the index patient and his parents was ex- RNA System (PreAnalytiX), according to standard protocols tracted from peripheral blood leukocytes using standard pro- provided by the manufacturers. One microgram of total RNA tocols. Array comparative genomic hybridization (array was reversely transcribed using random hexamer primer CGH) was performed with the use of high resolution 1.4 M (RevertAid First Strand cDNA Synthesis Kit; ThermoFisher NimbleGen oligonucleotide array CGH (Roche NimbleGen) Scientific), according to standard protocols provided by the according to standard protocols provided by the manufac- manufacturers. Quantifications of the target and reference turers. Analysis was carried out with Deva software (Roche gene in the proband and controls was carried out using NimbleGen). Analysis settings were as follows: aberration al- ViiA™ 7 Real-Time thermal cycler (Applied Biosystems). gorithm, ADM-2; threshold, 6.0; window size, 0.2 Mb; filter, For each cDNA sample, all reactions were run in triplicate. five probes, log2ratio = 0.29. The genomic profile was Relative expression of BGLAP and LMNA in the proband was J Appl Genetics (2018) 59:281–289 283 normalized to TBP reference transcript and to mean value of (Fig. 2a, b), hypotelorism (Fig. 2b), as well as digitate five controls. Reaction conditions and primer sequences are impressions most marked in the bone structures of the right available upon request. occipito-parietal region (Fig. 2c). Upon neurological as- sessment at the age of 7 months, the patient presented with Serum levels of bone turnover markers psychomotor retardation with global development that amounted to 3 months of age. Conventional chromosomal Biochemical analyses of serum levels of alkaline phosphatase, analysis performed on peripheral blood lymphocytes with inorganic phosphate, and total calcium were performed with a resolution of 550 bands per haploid genome showed nor- the use of standard laboratory methods. The serum osteocalcin mal male karyotype (46,XY). and intact parathyroid hormone levels were determined using chemiluminescence immunoassay (CLIA) (LIAISON XL; Serum levels of bone turnover markers Diasorin and ADIVIA Centaur XP Immunoassay System; Siemens respectively). The results were compared to the lab- Osteocalcin serum level (224 ng/ml) was 3.4-fold higher as oratory reference ranges. compared to the reference range (4.6–65.4 ng/ml). The serum concentrations of alkaline phosphatase (301 U/L), inorganic phosphate (4.6 mg/dl), and total calcium (10.7 mg/dl) were Results within normal ranges as compared to the reference values (142–335 U/L, 3.3–5.6 mg/dl, 8.8–10.8 mg/dl, respectively), Clinical report while intact parathyroid hormone was slightly lowered (12.6 pg/ml) in comparison to the reference range (18.5– The proband, a 5-month-old male patient of Polish ethnic- 88.0 pg/ml). ity, was born by spontaneous delivery after uneventful pregnancy (G1P1) at 38 weeks of gestation to a non- consanguineous and healthy 32-year-old mother and a Array comparative genomic hybridization (array CGH) 33-year-old father. At birth, his weight was 2900 g (3rd– 10th percentile), length 57 cm (75th–90th percentile), head Array CGH detected a previously unreported duplication at circumference 30 cm (below 3rd percentile), and Apgar chromosome 1q22-q23.1 (chr1:155927620–157198170; score was 10. Physical examination after birth showed hg19), encompassing 42 protein coding genes, including trigonocephaly and associated facial dysmorphism. BGLAP, encoding osteocalcin, and LMNA, encoding lamin Abdominal and transfontanellar ultrasounds performed af- A/C (Fig. 3a). ter birth were unremarkable. Hearing tests and ophthalmo- logic examinations were carried out during the first week after birth and repeated regularly throughout the first Quantitative real-time PCR (qPCR) and breakpoint months of life and were normal. The boy was referred to analysis the genetic clinic for diagnosis and first investigated by a clinical geneticist at the age of 5 months. Upon examina- qPCR confirmed the 1q22-q23.1 duplication in the proband tion, he presented with global developmental delay, severe and excluded its presence in both unaffected parents. muscular hypotonia, and craniofacial dysmorphic features Subsequent rounds of qPCR narrowed down the region of comprising prominent metopic ridge, trigonocephaly, high- duplication and allowed for the design of primers for arched palate, prominent occiput, hypotelorism, shallow breakpoint sequencing. Sequencing of the breakpoints re- orbits, and low-set, posteriorly rotated ears (Fig. 1a, b). vealed an insertion of four nucleotides (TTCT) at one of the His body weight was 5.5 kg (below 3rd percentile). CT breakpoints. The exact size of the duplication was scan of the head performed at the age of 7 months showed 1,255,998 bp (chr1:155931219–157187216; hg19). premature fusion of the metopic suture along with unilat- Breakpoint sequencing results were shown in Fig. 3b. eral right-sided lambdoid craniosynostosis (Fig. 1c), as well as thin and hypoplastic corpus callosum, morpholog- ical abnormalities of the median brain structures, including BGLAP and LMNA relative expression abnormal development of the white matter (Fig. 1d), and Chiari malformation (Fig. 1e). 3D modeling of the patient’s The analysis of BGLAP and LMNA relative expression per- skull performed with the use of RadiAnt DICOM Viewer formed in blood samples of the proband and five controls showed posterior plagiocephaly (Fig. 2a) due to premature- revealed 1.8-fold increase of BGLAP expression and 1.4-fold ly closed right lambdoid suture (Fig. 2c) and prominent increase of LMNA expression in the proband in reference to metopic ridge due to premature metopic synostosis the mean value of controls (Fig. 4). 284 J Appl Genetics (2018) 59:281–289 Fig. 1 Facial view of the proband showing craniofacial abnormalities comprising a trigonocephaly with prominent metopic ridge, shallow orbits, proptosis, and hypotelorism and b flat facial profile, prominent occiput, and low-set, posteriorly rotated ears. c CTscan of the head showing premature synostosis of the metopic suture (trigonocephaly) and right lambdoid suture (indicated in red). MS—metopic suture, CS— coronal suture, LS—lambdoid suture. d CT scan of the head (sagittal view) showing thin and hypoplastic corpus callosum (marked with a white arrow) as well as morphological abnormal- ities of the median brain struc- tures, including abnormal devel- opment of the white matter (marked with a yellow arrow). e CT scan of the head (coronal sec- tion) showing Chiari malforma- tion; white arrow indicates downward displacement of the right cerebellar tonsil through the foramen magnum Discussion RUNX2 duplications (Mefford et al. 2010), and MSX2 du- plications (Kariminejad et al. 2009). The fusion of cranial Genetic changes underlying most of the CS types, especial- sutures is orchestrated by an interplay between collagen ly other than coronal synostosis, remain largely unknown. fibers and mesenchymal cells that differentiate into osteo- A small proportion of metopic synostosis is caused by blasts, osteoclasts and osteocytes upon mechanical stress. 9p22 deletions and point mutations in FREM1 (Vissers et The molecular origin of CS has been linked to mutations in al. 2011). However, most of the cases remain undiagnosed genes encoding osteoblastogenic proteins that trigger the at a molecular level. Complex CS may rarely result from premature osteogenesis in cranial sutures via different mo- mutations in a recently discovered gene ERF, which en- lecular pathways (Katsianou et al. 2016). codes for a transcription factor (Twigg et al. 2013). In this paper, we describe a previously unreported de novo Furthermore, complex forms of the disease may be also 1.26 Mb duplication at chromosome 1q22-q23.1 identified in caused by chromosomal rearrangements, including small a sporadic male proband presenting with complex CS submicroscopic segmental aberrations referred to as copy (metopic and right-sided lambdoid synostosis), muscular hy- number variations (CNVs), which are estimated to account potonia, psychomotor retardation, and facial dysmorphism. for 10–15% of CS (Stratton et al. 1986; Eshel et al. 2002; The duplication encompasses 42 protein coding genes, includ- Wilkie et al. 2010; Massalska et al. 2014). Several interest- ing BGLAP and LMNA, both implicated in osteoblast differ- ing examples of CNVs resulting in craniosynostosis in- entiation, which are most probably involved in the pathogen- clude IHH regulatory mutations (Klopocki et al. 2011), esis of the clinical phenotype observed in our patient. J Appl Genetics (2018) 59:281–289 285 Fig. 2 3D modeling of the patient’s skull. a Aerial view presenting section presenting prematurely closed right lambdoid suture with digitate asymmetric posterior plagiocephaly and prominent metopic ridge (black impressions (indicated by black arrows) most marked in the right arrow) due to premature metopic synostosis. b Frontal view showing occipito-parietal region prominent metopic ridge (black arrow) and hypotelorism. c Horizontal BGLAP encodes osteocalcin (OCN), the most abundant required as molecular switches for Bglap expression. The non-collagen component of bone extracellular matrix. The gene’s activity during osteogenesis reflects the stages of oste- protein promotes matrix mineralization by high binding prop- oblast differentiation. Bglap is transcriptionally repressed in erties for calcium and hydroxyapatite, thus having a pivotal proliferating cells by Msx2, whereas in mature osteoblasts role in osteogenesis (Kruse and Kracht 1986;Sandberg etal. Dlx3, Dlx5, and Runx2 are recruited to initiate the gene tran- 1993;McGuigan et al. 2010). There are several signal trans- scription. Thus, OCN is considered to be a major marker of duction cascades involved in osteogenesis during cranial su- mature osteoblasts (Hassan et al. 2004). Of note, studies on rat ture development, including the MAPK/ERK pathway (acti- models demonstrated that Bglap expression level (as well as vated by FGFRs), SMAD signaling network, and Wnt/β- other bone-associated extracellular matrix molecules) is up- catenin pathway. Hyperactivation of these pathways results regulated in calvarial dura matter, directly underlying fusion in premature closure of sutures leading to craniofacial abnor- of sutures (Greenwald et al. 2000). To date, genetic abnormal- malities (Katsianou et al. 2016). Two major downstream target ities directly affecting the BGLAP have not been reported to proteins for these signaling cascades, Runx2 and Msx2, are cause premature closure of sutures. However, several studies Fig. 3 a Interstitial duplication in the index at 1q22-q23.1 encompassing (chr1:155931219–157187216; hg19), and an insertion of four LMNA and BGLAP genes, identified by means of array CGH (Roche nucleotides (TTCT) at one of the breakpoints NimbleGen). b Breakpoint sequencing results: a 1.26 Mb duplication 286 J Appl Genetics (2018) 59:281–289 1999; Maraldi et al. 2006). Based on clinical features, laminopathies could be organized into four groups: muscle disorders, lipodystrophies, neuropathies, and accelerated ag- ing disorders. The explanation of pleiotropic effect of various mutations in a single gene is attributed to the differences in the molecular mechanisms via which the variants affect the pro- tein function. These include abnormal protein structure, alter- ation of its charge, or failure of the post-transcriptional pro- cessing of LMNA. Unprocessed protein is accumulated in the cells and incorporated into the nuclei where it interferes with the nuclear integrity, resulting in destabilization of the nucleus structure (Worman and Bonne 2007). The pathomechanism underlying a variety of phenotypes Fig. 4 Relative expression levels of BGLAP and LMNA genes in blood found in human laminopathies has been investigated in both in samples of the proband and controls indicating 1.8-fold increase of vitro and in vivo studies. The features associated with LMNA BGLAP expression and 1.4-fold increase of LMNA expression in the loss-of function mutations arise from primarily affected MSCs proband compared to the mean value of five healthy controls. Error and include reduction in muscle mass, defects of bone forma- bars represent standard deviation tion, and craniofacial symptoms, such as delayed closure of sutures as seen in mandibuloacral dysplasia (MAD) and have determined how mutations in key elements of the Hutchinson-Gilford progeria (Novelli et al. 2002;De aforementioned signal transduction pathways alter the Sandre-Giovannoli et al. 2003;Shen et al. 2003;Yangetal. BGLAP expression pattern in osteoblast derived from 2006; Kim et al. 2011). Studies using the spontaneous Lmna fused sutures. According to these reports, the gene expres- mutation (Dhe) mouse, which serves as a naturally occurring sion was elevated in patients with Apert syndrome, as well animal model for laminopathies, show that the cranial suture as in mice harboring Fgfr1 Pro250Arg Pfeiffer syndrome tissue that fails to fuse exhibits abnormal nuclear morphology, mutation, thus confirming the direct correlation between hypomineralization, and low level of collagen I and III expres- the increased level of osteogenic proteins and the patho- sion (Odgren et al. 2010). Furthermore, the important role of logical ossification of sutures in both human and mice LMNA in the formation of mineralized matrix has been dem- (Lemonnier et al. 2000, 2001; Zhou et al. 2000). These onstrated in vitro using human osteoblasts and MSCs. Lamin findings are consistent with the results of our study in A/C knock-down in these cell lines resulted in impaired os- which we observed an elevated blood expression of teoblastogenesis, enhanced osteoclast formation, and in- BGLAP and increased serum osteocalcin level in the pro- creased adipogenesis, which was associated with reduced band, probably due to the identified duplication. Of note, RUNX2, BGLAP,and ALP expression levels, as well as the the serum alkaline phosphatase (ALP) level was within a impaired RUNX2 nuclear binding activity (Akter et al. 2009; normal range. Based on our observations, we hypothesize Rauner et al. 2009). Consistent with these data, studies using −/− that the CNV results in the general overexpression of Lmna mice showed decreased bone volume and muscular BGLAP that may have occurred also locally during osteo- atrophy that occurred concomitantly with increased bone mar- genesis in fusing cranial sutures, leading to the craniosyn- row and inter-myofiber fat infiltration, in the 4-week-old mu- ostosisobservedinour patient. tants as compared to controls (Tong et al. 2011). Since pro- Another interesting gene included in the duplication found gressive muscle weakness is a principal sign in a number of in our proband was LMNA. LMNA encodes lamin A/C, a laminopathies, including Emery-Dreifuss muscular dystro- nuclear intermediate filament protein that plays a major role phy, limb-girdle muscular dystrophy, and Charcot-Marie- −/− in the structural organization of the nucleus and regulation of Tooth type 2B1 and has been reported in the Lmna mice, gene expression via interaction with signaling molecules and muscular hypotonia observed in our patient may also be at- transcription factors (Aebi et al. 1986). The role of lamin A/C tributed to the abnormal gene expression and functioning of in osteoblastogenesis is associated with its potential to control LMNA. In addition, psychomotor retardation manifested by the fate of mesenchymal stem cells (MSCs), which may dif- our proband may result not only from hypotonia and muscular ferentiate into either osteoblast or adipocytes. Different muta- weakness, but also from the impediment of the growth of the tions in LMNA disrupt the integrity of the nuclear envelope, patient’s brain. This is often seen in complex forms of CS, mostly in the cells subjected to mechanical stress, leading to a even in cases where there is no overt evidence for increased group of disorders known as laminopathies (Manilal et al. intracranial pressure. J Appl Genetics (2018) 59:281–289 287 Ethical approval All procedures performed in studies involving hu- Interestingly, LMNA gene dosage may be also implicated man participants were in accordance with the ethical standards of the in the pathogenesis of CS, as its overexpression correlates institutional and/or national research committee and with the 1964 with an elevated level of osteogenic factors including Helsinki Declaration and its later amendments or comparable ethical RUNX2 and OCN (Bermeo et al. 2015; Tsukune et al. standards. Ethics approval was granted by the Institutional Review Board of Poznan University of Medical Sciences. 2017). Consistently, we demonstrated that LMNA expres- sion measured in peripheral blood of the index patient was Conflict of interest The authors declare no conflict of interest. elevated by 1.4-fold in comparison with healthy controls. This slight overexpression may contribute to craniosynos- Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http:// tosis but is rather inconsistent with muscular hypotonia, as creativecommons.org/licenses/by/4.0/), which permits unrestricted use, this feature is related to decreased level of LMNA (Tong et distribution, and reproduction in any medium, provided you give appro- al. 2011). Considering a possibility that dosage imbalance priate credit to the original author(s) and the source, provide a link to the of other than LMNA and BGLAP genes could contribute to Creative Commons license, and indicate if changes were made. the observed phenotype, we analyzed the predicted effect of haploinsufficiency (HI) of all protein-coding genes includ- ed in the duplication. Out of seven genes with a high (< 10%) or moderate (< 25%) HI score (NES, CCT3, References MEF2D, LAMTOR2, ETV3, SSR2, NTRK1), none of them have been linked to craniosynostosis (Huang et al. 2010). A Aebi U, Cohn J, Buhle L, Gerace L (1986) The nuclear lamina is a partly overlapping deletion in the 1q22-q23.1 region has meshwork of intermediate-type filaments. Nature 323:560–564. https://doi.org/10.1038/323560a0 been recently described in a patient presenting with intel- Akter R, Rivas D, Geneau G et al (2009) Effect of Lamin A/C knock- lectual disability and multiple congenital anomalies, and down on osteoblast differentiation and function. J Bone Min Res 24: two of the HI genes, NES and MAF2D,wereshowntobe 283–293. https://doi.org/10.1359/jbmr.081010 necessary for normal neuron development in mice Aleksiuniene B, Preiksaitiene E, Morkuniene A et al (2018) A de (Ikeshima et al. 1995;Parket al. 2010; Aleksiuniene et al. novo 1q22q23.1 interstitial microdeletion in a girl with intel- lectual disability and multiple congenital anomalies including 2018). Therefore, dosage imbalance could possibly contrib- congenital heart defect. Cytogenet Genome Res 154:6–11. ute to mental retardation observed in the index patient. https://doi.org/10.1159/000486947 In conclusion, we hypothesize that the complex phe- Bermeo S, Vidal C, Zhou H, Duque G (2015) Lamin A/C acts as notype of our proband, although caused be a novel an essential factor in mesenchymal stem cell differentiation through the regulation of the dynamics of the Wnt/β-catenin 1q22-q23.1 duplication, does not result directly from pathway. J Cell Biochem 116:2344–2353. https://doi.org/10. the increased gene dosage of LMNA and BGLAP, but 1002/jcb.25185 additionally from the change of a regulatory landscape Cohen MM (1979) Craniosynostosis and syndromes with cranio- within the duplicated region. As a consequence, synostosis: incidence, genetics, penetrance, variability, and misexpression of LMNA and BGLAP in a specific de- new syndrome updating. 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Journal of Applied GeneticsSpringer Journals

Published: May 29, 2018

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