Association of insulin gene VNTR polymorphism with polycystic ovary syndrome

Variability in the number of tandem repeats of the insulin gene (INS VNTR) is known to influence several phenotypes, including polycystic ovary syndrome (PCOS), diabetes mellitus type 1, diabetes mellitus type 2, and birth weight. The presence of the class III allele of INS VNTR has been reported to be protective in diabetes mellitus type 1, but in contrary it increases the disease risk of PCOS and diabetes mellitus type 2. PCOS is a very common endocrinopathy in women of reproductive age. The etiology of PCOS is uncertain, but family history of this syndrome suggests a major genetic cause. The aim of this pilot study was to investigate the possible association of INS VNTR polymorphism with PCOS in Czech women. In PCOS, significantly higher WHR, BMI, G(0), G(180), I(30), Cp(0), Cp(30), Cp(60), AUC-I, AUC-Cp, and insulinogenic index and significantly lower AUC-G/AUC-I were found. No significant differences in INS VNTR genotype, phenotype, or allele frequencies were found between PCOS and controls. In spite of several differences in anthropometric and biochemical parameters (abdominal fat localization, increased beta-cell function, and lower insulin sensitivity in PCOS women), no effect of INS VNTR polymorphism was found on insulin secretion, insulin action, or any other screened parameter.