Eythymiadou A, Gautschi I, van Bemmelen MX, Sertedaki A, Giannakopoulos A, Chrousos G, Schild L, Chrysis D. A mild and transient form of autosomal recessive Pseudohypoaldosteronism type 1 (PHA1) caused by a novel mutation in the SCNN1A gene.
Am J Physiol Endocrinol Metab 2023. [PMID:
37134141 DOI:
10.1152/ajpendo.00332.2022]
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Abstract
OBJECTIVE
To investigate the genetic etiology in a cohort of patients with a clinical, biochemical, and hormonal profile suggestive of a mild and transient form of PHA1. Patients - Methods: Twelve PHA1 patients with clinical and biochemical data were analyzed. The coding regions of NR3C2 and SCNN1A genes were sequenced. Human αENaC wt, αF226C and αF226S ENaC variants, were expressed in Xenopus laevis oocytes. to evaluate ENaC activity. The protein expression of α ENaC wt and mutants was determined by Western blot.
RESULTS
All patients were homozygotes for the p.Phe226Cys of the a subunit of ENaC, resulting in significantly reduced ENaC activity (83% reduction). Quantitative western blot analysis was consistent with a reduced ENaC protein expression for the αF226C compared to wt.
CONCLUSIONS
We present 12 patients from 4 different families with a mild and transient autosomal recessive PHA1 due to a novel homozygous missense mutation in the SCNN1A gene. Functional studies showed that the p.Phe226Cys substitution mutation in ENaC leads to a partial loss of function resulting mainly from both a decrease in the intrinsic ENaC activity, and a reduction in channel expression at the protein level. The partial loss of ENaC function could explain the mild phenotype, variable expressivity, and the transient course of the disorder in these patients.
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