Commonly, CBAVD syndrome is characterized by genotypes with “mild” CFTR mutations in combination with the 5T allele (IVS-9T5 polymorphic variant), which is detected in 40–50% of CBAVD patients and in 4–5% individuals of Caucasian origin [11,12]. The gene discussed is CFTR; the disease is congenital bilateral aplasia of vas deferens from CFTR mutation.