CFTR (TG)m(T)n polymorphism in patients with CBAVD in a population expressing low incidence of cystic fibrosis

Chiang H-S, Lu J-F, Liu C-H, Wu Y-N, Wu C-C. CFTR (TG)m(T)n polymorphism in patients with CBAVD in a population expressing low incidence of cystic fibrosis. As it is well established that an association exists between congenital bilateral absence of the vas deferens (CBAVD) and cystic fibrosis gene mutations, we investigated CFTR(TG)m(T)n polymorphism within a Taiwanese population that exhibits a very low incidence of CF. Sixty-three patients with CBAVD and 86 age-matched normal control subjects were evaluated. Temporal temperature gradient gel electrophoresis was used for CFTR mutational analysis. No major CFTR mutation was found in the patient series. A single prominent CFTR mutation, IVS8-5T, was present; however, (50.8% of 63 cases and 33.3% of 126 alleles), and exhibited a high prevalence of 12 or 13 TG repeats (93.8% of 32 cases and 95.2% of 42 alleles with IVS8-5T). Although these results are similar to those of Japanese CBAVD patients, they are higher than the common frequency (about 21%) found among Caucasian CBAVD patients. The very high percentage (42.9%) of patients with no CFTR mutations is also an ethnic characteristic. We concluded that CBAVD patients from Taiwan, who express a very low incidence of CF, were less affected by CFTR mutations, with the exception of IVS8-5T linked to either 12 or 13 TG repeats, which does exhibit a high prevalence among CBAVD patients tested.