“Whoa! It’s like Spotify but for academic articles.”

Instant Access to Thousands of Journals for just $40/month

Try 2 weeks free now

Leth of fingers and penis are related through fetal Hox gene expression

TO THE EDITOR: In their study of the size of the male external genital organs and their relations to other body measures, Spyropoulos and colleagues 1 reported statistically significant positive relations of penile shaft length, glanular length, and total penile length with index finger length (Pearson correlation coefficient r = 0.324, 0.330, and 0.339, respectively). The authors were unable to provide an explanation for this observation. In two editorial comments, the finding was discounted as being likely spurious 2 or of questionable relevance for urologic practice and counseling. 3 Here we present an explanation for their finding which renders it unlikely to be spurious and which further may have practical implications. Across vertebrate species, including humans, the Homeobox ( Hox ) genes regulate limb development, including fingers and toes, as well as urinogenital system development, including the penis. 4 Therefore morphologic patterns of the fingers may be related to morphologic patterns of the external genitalia. Specifically, there is evidence that the human 2D:4D, ie, the relative length of the second digit (2D, index finger) to the fourth digit (4D, ring finger), is an early established (end of first trimester) sexually dimorphic trait. 5 Cross-racially, men tend to have shorter index fingers relative to ring fingers (ie, lower 2D:4D) than do women. This is in keeping with evidence that 2D:4D is negatively related to prenatal testosterone concentrations and positively related to prenatal estrogen exposure. Penis growth is also influenced by prenatal testosterone. Since a low 2D:4D is a pointer to high fetal testosterone exposure levels, it seems counterintuitive that 2D is positively related to penis length. However, we expect that 4D, not measured by Spyropoulos and colleagues, is even more strongly positively related to penis length. It only requires this hypothesized difference in slope, ie, in the positive relations of penis length regressed on 2D compared with penis length regressed on 4D, for there to be a negative relation between 2D:4D and penis length. This is a testable hypothesis for future research. Prenatal sex steroids have effects on the heart, liver, and brain in addition to the urinogenital system. 2D:4D has been reported as being related to a growing number of sex-dependent variables, including behavioral traits (eg, autism, depression, handedness, homosexuality, impulsivity, musical talent, sporting prowess, and visuo-spatial ability), adult-onset diseases (eg, breast cancer, coronary heart disease, and myocardial infarction), and fertility-related measures (eg, birth weight, family size, offspring sex ratio, and sperm counts). 5 Thus relations of finger length patterns and penis length are not surprising and may have practical implications in urology.</P> http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Urology Elsevier
Loading next page...
1 Page

You’re reading a free preview. Subscribe to read the entire article.

DeepDyve is your
personal research library

It’s your single place to instantly
discover and read the research
that matters to you.

Enjoy unlimited access and
personalized recommendations from
over 12 million articles from more than
10,000 peer-reviewed journals.

All for just $40/month

Try 2 weeks free now

Explore the DeepDyve Library

How DeepDyve Works

Spend time researching, not time worrying you’re buying articles that might not be useful.

Unlimited reading

Read as many articles as you need. Full articles with original layout, charts and figures. Read online, from anywhere.

Stay up to date

Keep up with your field with Personalized Recommendations and Follow Journals to get automatic updates.

Organize your research

It’s easy to organize your research with our built-in tools.

Your journals are on DeepDyve

Read from thousands of the leading scholarly journals from Springer, Elsevier, Nature, IEEE, Wiley-Blackwell and more.

All the latest content is available, no embargo periods.

See the journals in your area

Simple and Affordable Pricing

14-day free trial. Cancel anytime, with a 30-day money-back guarantee.

Monthly Plan

  • Read unlimited articles
  • Personalized recommendations
  • Print 20 pages per month
  • 20% off on PDF purchases
  • Organize your research
  • Get updates on your journals and topic searches


Best Deal — 25% off

Annual Plan

  • All the features of the Professional Plan, but for 25% off!
  • For the normal price of 10 articles elsewhere, you get one full year of unlimited access to articles.

billed annually