CFTR and male infertility: In males, the absence or severely reduced activity of CFTR protein due to genetic mutations can lead to excessive viscosity of the epididymal fluid and results in male infertility [11, 13] with congenital bilateral absence of vas deferens (CBAVD) [14, 15] when associated with (TG)m and Tn polymorphisms loci in intron 8 at the splice acceptor site of exon 9 of CFTR gene [16, 17].