A New Case Report of a CLCNKB Complex Heterozygous Mutation in Adult-Onset Type III Bartter Syndrome.

Background: Type III Bartter syndrome (BS) is an autosomal recessive renal tubular disease caused by the mutation of the chloride voltage-gated channel Kb (CLCNKB) gene. This condition is characterized by renal sodium loss, hypokalemia, metabolic alkaliosis, high renin, and high aldosterone levels.

Methods: We report a case of adult type III BS caused by a novel complex heterozygous mutation of the CLCNKB gene. The peripheral blood was extracted for whole genome DNA extraction, and the genome exon region of BS- related genes, was predicted by high-throughput sequencing and protein function prediction software. The selected mutation sites were verified by sequencing with Sanger method.

Results: The new complex heterozygous mutations of CLCNKB include heterozygous deletion of exon 2 - 20 of CLCNKB and nonsense mutation of exon 19, c.2010G>A (p.W670X). This complex heterozygous mutation has not been reported in humans.

Conclusions: For patients with high clinical suspicion of BS, a clear diagnosis should be made through genetic test-ing to improve patients' quality of life and provide genetic guidance.