High frequency of (TG)m Tn variant tracts in the Cystic Fibrosis Transmembrane Conductance Regulator Gene in men with high semen viscosity

Abstract

Objective: To evaluate a possible correlation between abnormal semen consistency and cystic fibrosis transmembrane conductance regulator (CFTR) gene mutations and variant tracts. Design: Study of CFTR mutations and variant tracts in men with high semen viscosity as compared with normospermic men. Setting: University-based centers for andrology, clinical biochemistry, and cystic fibrosis. Patient(s): Forty-six male partners from infertile couples with sine causa high semen viscosity compared with 72 normospermic men. Intervention(s): Semen sample collection. Main Outcome Measure(s): We obtained the (TG)mTn polymorphic tracts and a panel of 31 mutations of CFTR, semen viscosity, and semen variables. Result(s): The frequencies of the (TG)12 and T5 variant alleles were statistically significantly higher in men with high semen viscosity (17.4% and 7.6%, respectively) than in the normospermic control group (6.9% and 1.4%, respectively). The frequency of the genotypes carrying (TG)12 or T5 was statistically significantly higher in men with high semen viscosity (39.1%) than in the normospermic control group (16.7%). Four men with high semen viscosity showed the variant (TG)12T5 haplotype; one of these men presented variant tracts on both alleles. None of the normospermic controls showed a (TG)12T5 haplotype. Conclusion(s): Semen hyperviscosity could be considered a “minimal clinical expression” of cystic fibrosis; CFTR gene sequence variations may constitute the genetic basis for this disease