title: A novel mutation ofCLCNKBin a Korean patient of mixed phenotype of Bartter-Gitelman syndrome.
abstract: Bartter syndrome (BS) is an inherited renal tubular disorder characterized by low or normal blood pressure, hypokalemic metabolic alkalosis, and hyperreninemic hyperaldosteronism. Type III BS is caused by loss-of-function mutations inCLCNKBencoding basolateral ClC-Kb. The clinical phenotype of patients withCLCNKBmutations has been known to be highly variable, and cases that are difficult to categorize as type III BS or other hereditary tubulopathies, such as Gitelman syndrome, have been rarely reported. We report a case of a 10-year-old Korean boy with atypical clinical findings caused by a novelCLCNKBmutation. The boy showed intermittent muscle cramps with laboratory findings of hypokalemia, severe hypomagnesemia, and nephrocalcinosis. These findings were not fully compatible with those observed in cases of BS or Gitelman syndrome. TheCLCNKBmutation analysis revealed a heterozygous c.139G>A transition in exon 13 [p.Gly(GGG)465Glu(GAG)]. This change is not a known mutation; however, the clinical findings and in silico prediction results indicated that it is the underlying cause of his presentation.
authors.affiliation: Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Hee-Won
authors.initials: HW
authors.lastname: Cho
authors.affiliation: Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Sang Taek
authors.initials: ST
authors.lastname: Lee
authors.affiliation: Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Heeyeon
authors.initials: H
authors.lastname: Cho
authors.affiliation: Department of Pediatrics, Seoul National University Children's Hospital, Seoul, Korea.
authors.forename: Hae Il
authors.initials: HI
authors.lastname: Cheong
keywords: Bartter Syndrome; CLCNKB; Novel mutation