Although there are no reports of patients presenting mutations only in ClC-Ka, two patients presenting symptoms similar to those accompanying Bartter syndrome type IV—severe renal salt loss and sensorineural deafness—were described with loss-of-function mutations in both ClC-K isomers instead of barttin (Schlingmann et al., 2004; Nozu et al., 2008). The gene discussed is BSND; the disease is Bartter syndrome type 4.