Genetics and Male Infertility

About the CFTR Gene Mutations

Mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene cause congenital bilateral absence of the vas deferens (CBAVD) in approximately 1% of the infertile males. It is a common cause of azoospermia associated with low semen volume and acidic pH. These male will have normal testicular sperm, which are immotile due to the absence of vas deferens. ⁷

Approximately 80% of men with CBAVD are found to have at least one allele mutated in the CFTR gene. ⁴ The most common CFTR mutation is a three base- paired deletion at position 508 that causes an in-frame deletion of a phenyloalanine. The mutant protein is known as ∆ F508 CFTR. ⁸

Congenital unilateral absence of the vas deferens (CUAVD) is a similar condition that involves aplasia of only one side of the vas deferens. ⁴ It presents with infertility rarely. CFTR gene mutations have been reported in 43% of men with unilateral absence of the vas deferens. ⁷