The PON1-108C/T polymorphism, and not the polycystic ovary syndrome, is an important determinant of reduced serum paraoxonase activity in premenopausal women.

Background: Because serum paraoxonase activity is influenced by the -108C/T polymorphism in the PON1 gene, we studied its involvement in the decreased paraoxonase activity recently described in the polycystic ovary syndrome (PCOS).

Methods: Paraoxonase activity, PON1-108C/T genotypes and clinical, hormonal and biochemical variables were evaluated in a case-control study involving 139 consecutive PCOS patients and 85 healthy controls matched for BMI and prevalence of smoking.

Results: Women homozygous for -108T presented with reduced serum paraoxonase activity compared with carriers of C alleles (P < 0.001), both in PCOS patients and in controls. Although homozygosity for T alleles was more prevalent in PCOS patients than in controls (P = 0.003), serum paraoxonase activity was not significantly different in the PCOS and control groups. In a stepwise multivariate linear regression model, homozygosity for PON1-108T alleles was the only significant predictor of the logarithm of serum paraoxonase activity (beta = -0.328, t = -4.176, P < 0.001).

Conclusions: In premenopausal women from the Spanish population, the PON1-108C/T polymorphism, and not PCOS, is an important determinant of serum paraoxonase activity.