Sequence-ready physical map of the mouse Chromosome 16 region
with conserved synteny to the human Velocardiofacial syndrome
region on 22q11.2
Feng Chen, Marcia Budarf,
Robert D. Miller,
Beverly S. Emanuel,
Roger H. Reeves
Physiology 205, Johns Hopkins University School of Medicine, 725 N. Wolfe St., Baltimore, Maryland 21205, USA
Dept. of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma 73019, USA
Division of Human Genetics and Molecular Biology, The Children’s Hospital of Philadelphia, Pennsylvania 19104, USA
The Wistar Institute, Philadelphia, Pennsylvania 19104, USA
Torrey Pines Institute for Molecular Studies, San Diego, California 92121, USA
Dept. of Biology, University of New Mexico, Albuquerque, New Mexico, USA
Received: 4 November 1998 / Accepted: 21 December 1998
Abstract. Proximal mouse Chromosome (Chr) 16 shows con-
served synteny with human Chrs 16, 8, 22, and 3. The mouse Chr
16/human Chr 22 conserved synteny region includes the Di-
George/Velocardiofacial syndrome region of human Chr 22q11.2.
A physical map of the entire mouse Chr 16/human Chr 22 region
of conserved synteny has been constructed to provide a substrate
for gene discovery, genomic sequencing, and animal model devel-
opment. A YAC contig was constructed that extends ca. 5.4 Mb
from a region of conserved synteny with human Chr 8 at Prkdc
through the region conserved with human Chr 3 at DVL3. Sixty-
one markers including 37 genes are mapped with average marker
spacing of 90 kb. Physical distance was determined across the
2.6-Mb region from D16Mit74 to Hira with YAC fragmentation.
The central region from D16Jhu28 to Igl-C1 was converted into
BAC and PAC clones, further refining the physical map and pro-
viding sequence-ready template. The gene content and borders of
three blocks of conserved linkage between human Chr 22q11.2
mouse Chr 16 are refined.
Patients with haploinsufficiency of human chromosomal region
22q11.2 are characterized by cardiac abnormalities involving the
outflow tract, thymic hypoplasia with resultant T cell deficit, para-
thyroid hypoplasia resulting in hypocalcemia, and characteristic
facial features. Some patients also demonstrate palatal abnormali-
ties (Driscoll 1994). This continuum of anomalies has been iden-
tified under a variety of clinical names, including Velocardiofacial
syndrome (VCFS), DiGeorge syndrome (DGS), Shprintzen syn-
drome, Conotruncal Anomaly Face syndrome, and CATCH-22
(DiGeorge 1965; Kinouchi et al. 1976; Shprintzen et al. 1981;
Wilson et al. 1993). It will be referred to here as DGS/VCFS.
The deletions of Chr 22 that result in DGS/VCFS typically
extend for 2–3 Mb on Chr 22q11.2. The proximal endpoints cluster
just proximal to LAN/DGCR2/IDD (referred to here as LAN; note
that the orthologous mouse gene is Dgsc), while the distal deletion
endpoints occur at several different sites spread over 1 Mb. It
appears that deletions usually occur owing to recombination in
large (ca. 200 kb) blocks of imperfectly repeated sequences (Hal-
ford et al. 1993; Morris et al. 1993; Shaikh et al. 1999). A com-
monly deleted region has been identified that extends from LAN to
D22S1742E (rev. Budarf and Emanuel 1997; Scambler et al.
1998), and efforts to identify candidate genes have focused on this
DGS/VCFS core region. However, a few patients have deletions or
translocations on Chr 22 that apparently do not include the core
region (Emanuel et al. 1998; Kurahashi et al. 1996; McQuade et al.
1998; O’Donnell et al. 1997).
Twenty-six genes have been identified in the DGS/VCFS core
region, and an additional 10 genes have been reported from the
somewhat less frequently deleted region immediately distal to it.
Genes from this region of HSA22 map to a region of conserved
synteny on proximal Chr 16 in the mouse (Botta et al. 1997; Galili
et al. 1997; Puech et al. 1997; Sutherland et al. 1998). While the
gene content of Chr 16 and the DGS/VCFS region is largely con-
served, the mouse and human chromosomes are rearranged relative
to each other. The human genes are present on mouse Chr 16 in
multiple blocks of conserved synteny.
Both YAC and BAC-based STS content maps of the mouse
DGS/VCFS conserved synteny region on Chr 16 have been pre-
sented (Puech et al. 1997; Sutherland et al. 1998). These maps are
extended here to bridge the entire Chr 22 conserved syntenic re-
gion. The maps are further enhanced by additional markers, in-
cluding a total of 37 genes, which more extensively define the
blocks of conserved synteny between Chr 16 and HSA22 (Table
1). Two genes not previously recognized in mouse or human,
Kelchl and D16Jhu23e, have been identified and localized on the
contig. Prodh, not previously mapped in mouse, has been localized
on the contig. YAC fragmentation was used to measure physical
distance on the STS content map. The YAC contig was converted
to bacterial based clones (PACs and BACs) that provide sequence-
ready template across the region. This genomic information and
ongoing comparative sequencing in this region contribute directly
to development of animal models of DGS/VCFS and further un-
derstanding of the etiology of this deletion syndrome.
Materials and methods
Isolation and handling of YAC and BAC clones.
YACs were iden-
tified by library screening and from the March 1997 release of the WCGR
Mouse Physical Mapping Project (http://www-genome.wi.mit.edu/). The
Whitehead I library available through Research Genetics (Huntsville, Ala.;
Kusumi et al. 1993) and Princeton University (Rossi et al. 1992) YAC
libraries were screened by use of PCR pools. The St. Mary’s (Chartier et
al. 1992) and ICRF (Larin et al. 1991) YAC libraries residing at Baylor
University were screened by use of PCR pools for the combined libraries.
WCGR Mouse Physical Mapping Project database was searched, and
YACs containing markers known to reside in the region were ordered from
Research Genetics. YAC clones were checked for integrity by PFGE, and
single colonies of deleting YACs were screened to find the largest possible
Correspondence to: R.H. Reeves
Mammalian Genome 10, 438–443 (1999).
© Springer-Verlag New York Inc. 1999