Differential diagnosis of classical Bartter syndrome and Gitelman syndrome: Do we need genetic analysis?

Year 2021, , 254 - 259, 27.10.2021

Sercin Guven Ibrahim Gokce Ceren Alavanda Neslihan Cıcek Ece Bodur Demırcı Mehtap Sak Serim Pul Ozde Nisa Turkkan Nurdan Yıldız Pinar Ata Harika Alpay

https://doi.org/10.5472/marumj.1012351

Abstract

Objective: Classical Bartter syndrome (cBS) and Gitelman syndrome (GS) are genotypically distinct, but there is a phenotypic overlap
among these two diseases, which can complicate the accurate diagnosis without genetic analysis. This study aimed to evaluate the
correlation between clinical and genetic diagnoses among patients who have genetically defined cBS and GS.
Patients and Methods: The study included 18 patients with homozygous/compound heterozygous CLCNKB (NM_000085) (n:10/18)
and SLC12A3 (NM_000339) (n:8/18) mutations. Biochemical, clinical and radiological data were collected at presentation and at the
last visit.
Results: In cBS group age at diagnosis, median plasma potassium and chloride concentrations were significantly lower and median
plasma HCO3 and blood pH values were significantly higher. Patients with GS had significantly lower median plasma magnesium
concentrations and urinary calcium/creatinine ratio. One child with GS had normocalciuria, two children with cBS had hypocalciuria
and hypomagnesemia. Low estimated glomerular filtration rate (eGFR) (ml/dk/1.73m2) and growth failure were more evident in cBS
group. In patients with cBS, nine different CLCNKB gene mutations were detected, five of them were novel. Novel mutations were:
one nonsense (c.66G>A, p.Trp22*), one missense (c.499G>A, p.Gly167Ser) and three splice-site (c.867-2delA; c.499-2insG; c.1930-
2A>C) mutations. In patients with GS, six different SLC12A3 gene mutations were found.
Conclusions: It may not always be possible to clinically distinguish cBS from GS. We suggest to perform a genotypic classification if
genetic analysis is possible.

Keywords

Bartter syndrome, Gitelman syndrome, Kidney tubuler disease, Hypokalemic metabolic alkalosis

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