Genetics and infertility II - Candidate genes in polycystic ovary syndrome

The candidate gene approach has already paid some dividends in trying to un derstand the complex genetics of polycystic ovary syndrome (PCOS). In terms of steroidogenic abnormalities, CYP11a-encoding P450 side chain cleavage-a ppears to be a major susceptibility locus. In relation to the well-describe d metabolic disturbances in PCOS, the insulin gene variable number tandem r epeat (VNTR) appears to be a promising candidate, at least in populations s tudied in the UK. Finally, genes implicated in ovarian follicular developme nt may have a role in the aetiology of PCOS, as demonstrated by recent iden tification of the follistatin gene as a potential disease locus. It seems u nlikely that PCOS can be explained on the basis of a single gene disorder a lthough, in a given family, one gene may have a predominant effect. An olig ogenic model seems the most appropriate basis on which to understand the ge netic origins of this very common disorder. The candidate gene approach has been useful to date, but it may prove important in the near future to perf orm an anonymous genome-wide scan to identify hitherto unheralded susceptib ility loci.