Exclusion of Serum- and Glucocorticoid-Induced Kinase 1 (SGK1) as a Candidate Gene for Genetically Heterogeneous Renal Pseudohypoaldosteronism Type I in Eight Families

Objective: Autosomal-dominant pseudohypoaldosteronism type 1 (PHA1) is mostly caused by mutations in the mineralocorticoid receptor (NR3C2) gene. However, several kindreds with clinical signs of PHA1 but without NR3C2 gene mutations or deletions are reported. Serum- and glucocorticoid-induced kinase 1 (Sgk1) is involved in epithelial sodium reabsorption by facilitating the accumulation of the epithelial sodium channel in the plasma membrane. Therefore variations in the SGK1 gene may aggravate renal salt loss or cause PHA1. Methods: The SGK1 genewas sequenced in 10 patients with the typical clinical signs of PHA1 but without NR3C2 or SCNN1A, SCNN1B and SCNN1C gene mutation. Results: No disease-causing SGK1 gene mutation was detected in the studied PHA1 patient group. Two novel intronic SNPs which were also present in the normal population were detected in 2 patients. Conclusion: Our data do not support that SGK1 gene variations are disease-causing factors in genetically unexplained PHA1. Therefore, systematic investigation of other factors downstream of the MR involved in epithelial sodium reabsorption is warranted in patients with autosomal-dominant PHA1.