Variations in the Expression of the Polycystic Ovary Syndrome Phenotype

Three main polycystic ovary syndrome (PCOS) phenotypes may be distinguished. The most common, including at least two-thirds of the patients, is classic PCOS with an anovulatory hyperandrogenic phenotype. In 90% of the patients, polycystic ovaries are present. Obesity is common, but the prevalence varies largely among populations. Diabetes, altered glucose tolerance, metabolic syndrome, and increased circulating cardiovascular risk factors are also present, but their prevalence is largely influenced by body weight. The second phenotype, ovulatory PCOS, identifies patients presenting with hyperandrogenism and polycystic ovaries but ovulatory cycles. These patients seem to present a mild form of PCOS with insulin resistance and hyperinsulinemia being less severe and with a lower prevalence of metabolic and cardiovascular risk factors than in patients with classic PCOS. In these patients, body weight is often normal or only slightly increased, and changes in body weight may move the patients from one hyperandrogenic phenotype to another. The last main phenotype, normoandrogenic PCOS, is present in women with chronic anovulation and polycystic ovaries but normal androgen levels. Data on this group of patients are few and more studies are needed.