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Medical Science Monitor Basic Research


Late-Onset Bartter Syndrome Type II Due to a Homozygous Mutation in KCNJ1 Gene: A Case Report and Literature Review

Unusual clinical course, Rare disease

Khaled A. Elfert, David S. Geller, Carol Nelson-Williams, Richard P. Lifton, Hassan Al-Malki, Awais Nauman

Qatar Department of Internal Medicine, Hamad Medical Corporation, Doha, Qatar

Am J Case Rep 2020; 21:e924527

DOI: 10.12659/AJCR.924527

Available online: 2020-08-27

Published: 2020-09-30


BACKGROUND: Bartter syndrome is a rare genetic disease characterized by hypokalemia, metabolic alkalosis, and hyperreninemic hyperaldosteronism. Five different subtypes have been described based on the genetic defect identified. Bartter syndrome type II is caused by homozygous or compound heterozygous loss-of-function mutations in the KCNJ1 gene encoding ROMK. This subtype is typically described as a severe antenatal form of the disease, often presenting with polyhydramnios before childbirth.
CASE REPORT: Here, we describe the case of a 26-year-old man who presented with generalized body weakness and hypokalemia and was ultimately diagnosed with Bartter syndrome type II based on his clinical features coupled with the identification of a homozygous missense mutation in KCNJ1.
CONCLUSIONS: To the best of our knowledge, this is the fifth case of late-onset Bartter syndrome type II. Interestingly, the mutation identified in our patient has been previously described in patients with antenatal Bartter’s Syndrome. The late presentation in our patient suggests a surprising degree of phenotypic variability, even in patients carrying the identical disease-causing mutation.

Keywords: Bartter Syndrome, Hypokalemia, Mutation, Missense, Nephrocalcinosis, Potassium Channels, Inwardly Rectifying