Zelikovic et al. (2003) examined the clinical, biochemical and genetic characteristics of a very large inbred Bedouin kindred in the lower Galilee with hereditary hypokalemic tubulopathy. All study participants underwent genetic linkage analysis. Mutation analysis was performed in affected individuals. Linkage analysis in affected patients excluded the TSC gene, SLC12A3, as the mutated gene, but demonstrated linkage to the Cl- channel gene, CLCNKB, on chromosome 1p36. Mutation analysis by direct sequencing revealed a novel homozygous missense mutation, arginine 438 to histidine (R438H), in exon 13 of CLCNKB in all patients. Zelikovic et al. (2003) indicated that the exact role of the CLCNKB R438H mutation in the pathogenesis of the electrolyte and mineral abnormalities in Gitelman syndrome and classic Bartter syndrome remains to be established.