Familial polycystic ovaries: a genetic disease?

High resolution ultrasonography was used to establish the presence of polycystic ovaries (PCO) in 50 women with symptoms of polycystic ovary syndrome and in 17 women with congenital adrenal hyperplasia. One hundred and thirty-seven post-menarcheal, premenopausal female members of the families of these patients were scanned to assess the heredity of the condition. Familial PCO was found in 56 of the 61 pedigrees (92%) in which sufficient members were available for study. The frequency of PCO in the relatives of the patients with congenital adrenal hyperplasia was no different from that found in the main group. Twenty-four out of thirty-six (67%) mothers of probands and 45 out of 52 (87%) sisters of probands were affected. The segregation ratio (fraction of females affected) for all sibships was 107 out of 133 (80.5%). The volumes of the polycystic ovaries (mean 9.97 ml, 95% confidence limits (CL) +/- 0.75) were significantly different from those of the normal ovaries (mean 5.38 ml, 95% CL +/- 0.26) (P less than 0.0001), although there was no significant difference between the volumes of the ovaries of the probands and those of their affected relatives. Even after allowing for a high frequency of PCO in the general population (22%), the observed segregation ratios were significantly different from those predicted for autosomal dominant (P less than 10(-4)) and X-linked dominant (P = 0.0002) modes of inheritance. A number of mechanisms which might account for the observed segregation ratio are considered. These include meiotic drive due to a genetic segregation distorted, vertical transmission of an infective agent, and environmental factors, such as the effect of maternal androgen on gonadal development.