Gene dose effect between a fat mass and obesity-associated polymorphism and body mass index was observed in Korean women with polycystic ovary syndrome but not in control women.

Objective: To examine the association between fat mass and obesity-associated (FTO) polymorphisms and polycystic ovary syndrome (PCOS) in Korean women.

Design: Case-control study.

Setting: University department of obstetrics and gynecology.

Patient(s): Women with (n = 552) or without (n = 559) PCOS.

Intervention(s): Genotyping was performed.

Main Outcome Measure(s): FTO rs9939609 genotype distribution and correlation between variants in this gene and PCOS phenotypes.

Result(s): The mean body mass index (BMI) of the patients was significantly higher than that of the control subjects (22.0 ± 4.1 kg/m(2) vs. 20.1 ± 2.5 kg/m(2)), but most (81.3%) of the patients were not obese. FTO rs9939609 was not significantly associated with PCOS itself. However, a positive correlation was observed between the number of variant alleles and BMI in women with PCOS: Each additional copy of the variant allele increased BMI by a mean (95% confidence interval) of 4.8% (1.4%-8.3%) or 1.11 kg/m(2) (1.03-1.20 kg/m(2)) after adjusting for age. This correlation was not observed in the control subjects.

Conclusion(s): FTO rs9939609 was not a major determinant of PCOS. However, in the women with PCOS who were primarily nonobese, a gene dose effect was observed for BMI. The FTO gene may play an influential role in predisposition to PCOS via an association with obesity.