The FTO (Fat mass and obesity associated) locus has recently been associated with obesity and type 2 diabetes (T2D) in humans. To understand the role of the FTO gene in polycystic ovary syndrome (PCOS) we genotyped single nucleotide polymorphism (SNP) rs1421085 (C/T) in women with PCOS (n = 207) and controls (n = 100) from a Central European population. The homozygous C/C genotype showed increased prevalence in PCOS patients either obese or with metabolic syndrome (MetS) compared to lean PCOS patients or controls (27.6%, 38.9%, 22.3%, and 16.3%, respectively). In logistic regression, this genotype strongly associated with MetS (P < 0.0001, OR 3.2, 95% CI 1.8-5.7) and impaired fasting glucose (IFG) with P < 0.0007, OR 7.7, 95% CI 2.1-28.6, independently of BMI or age, and to AUC(gluc) during OGTT (P < 0.0001, alpha = 0.99), indicating an influential role of the FTO gene in the glucose intolerance component of MetS. (C) 2008 Elsevier Inc. All rights reserved.