Two novel mutations in the CLCNKB gene leading to classic Bartter syndrome presenting as syncope and hypertension in a 13-year-old boy.

Classic Bartter syndrome is a rare condition caused by mutations in the CLCNKB gene and characterised by metabolic alkalosis, hypokalaemia, hyper-reninaemia and hyperaldosteronism. Early signs and symptoms usually occur before a child's sixth birthday and include polyuria and developmental delay. We treated a 13-year-old Vietnamese boy with this syndrome presenting with atypical presentations including syncope and hypertension, but normal growth and development. All common causes of hypertension were ruled out. Genetic testing found two novel mutations in the CLCNKB gene, that is, Ser12Ala (exon 2) and Glu192Ter (exon 6). His estimated glomerular filtration rate was 61 mL/min/1.73 m2 and a kidney biopsy showed focal segmental glomerulosclerosis. He was well managed with long-term enalapril therapy instead of non-steroidalanti-inflammatory drugs which are recommended in managing the increased prostaglandin E2 production in Bartter syndrome. Paediatricians should be alerted with the variability in its presentation. To preserve the kidney function, treatment must include preventing factors damaging the kidneys. © BMJ Publishing Group Limited 2020. No commercial re-use. See rights and permissions. Published by BMJ.