To test whether the two newly identified mutations, G167V and G289R, were responsible for the occurrence of BS in the affected carriers, we expressed the same amount (5 μg) of wild type and mutant ClC-Kb channels cDNA together with barttin (1:1 ratio) in HEK 293 cells and recorded chloride currents through whole-cell patch-clamp. The gene discussed is BSND; the disease is Bloom syndrome.