A TWIN STUDY OF POLYCYSTIC-OVARY-SYNDROME

Objective: To examine the role of genetic and environmental factors in polycystic ovary syndrome (PCOS) by using the classic twin model. Set ting: Outpatient clinic of the Royal Hospital for Women, Paddington, S ydney, New South Wales, Australia. Patients: A group of 19 monozygotic (MZ) and 15 dizygotic (DZ) twin pairs identified from the national tw in register. Interventions: Ultrasound, clinical, and biochemical para meters were used to define PCOS. Results: Eleven pairs of twins (5 MZ, 6 DZ pairs) were scan-discordant (i.e., one twin had scan-PCOS and th e co-twin did not). Model-fitting analysis suggested that fasting insu lin level, androstanediol glucuronide, and body mass index (BMI) were significantly influenced by genetic factors. Conclusion: This study su ggests that PCOS is not the result of a single autosomal genetic defec t, but rather environmental factors, perhaps both intrauterine and ext rauterine, are involved in the pathogenesis of this disorder or that P COS may be an X-linked disorder or the result of polygenic factors. Ho wever, fasting insulin level, androstanediol glucuronide, and BMI did appear to be under significant genetic influence.