Submitted by Administrator on Thu, 09/05/2013 - 09:17
Research news from the Department's Vision Lab
Individual differences in the ratio of the length of the index finger to that of the ring finger are known to reflect prenatal levels of sex hormones, but it has not been known how this effect actually arises. In a paper in the current issue of Human Genetics, members of the Department's Vision Laboratory identify a gene that may mediate between prenatal exposure to sex hormones and digit ratio.
Psychologists have been interested in digit ratio as an index of prenatal hormone exposure because androgens are known to have organising effects on the brain. And indeed many psychological traits and conditions correlate with digit ratio. Several local authors have previously contributed to this field. For example, Simon Baron-Cohen and Sally Wheelwright were members of a group that showed a relationship between digit ratio and the 'systemizing quotient' (Personality and Individual Differences, 2010), while Mei Chern Leow and Greg Davis have recently reported a relationship between digit ratio and the face inversion effect (Psychonomic Bulletin & Review, 2012).
Digit ratio is known to be heritable. In a whole-genome association study, Adam Lawrance-Owen, Gary Bargary, Jenny Bosten, Patrick Goodbourn and John Mollon have now shown that digit ratio is very significantly correlated with variation in the promoter region of a gene called SMOC1. This gene encodes a protein that is secreted into the cellular matrix during differentiation of osteoblasts and is a known antagonist of bone morphogenetic proteins. Rare mutations of the gene in human patients are associated with abnormalities of the fingers such as syndactyly and oligodactyly; and knock-out mice exhibit similar features. Moreover, in prostate tissue, SMOC1 is up-regulated by androgen and is down-regulated by oestrogen. So the new paper puts forward the hypothesis that prenatal hormone levels have their effect on digit ratio via the gene SMOC1.
The paper can be accessed here.