Loss-of-function mutations of several genes encoding those transporters involved in salt reabsorption at the TAL cause different types of BS: SLC12A1 (Na-K-2Cl cotransporter NKCC2) causes type I BS (OMIM #601678) [7], KCNJ1 (K+ channel, ROMK) causes type II BS (OMIM #241200) [8] and CLCNKB (Chloride Channel Protein ClC-Kb) causes type III BS (OMIM #607364) [9]. The gene discussed is CLCNKB; the disease is Bloom syndrome.