Two Japanese patients with the renal form of pseudohypoaldosteronism type 1 caused by mutations of NR3C2.

Pseudohypoaldosteronism type 1 (PHA1) is a disease characterized by neonatal salt loss due to aldosterone resistance. Two types of PHA1 are known: an autosomal recessive systemic form and an autosomal dominant renal form. The cause of the renal form of PHA1 is heterozygous mutations in NR3C2, which encodes the mineralocorticoid receptor (MR). We encountered two female Japanese infants with the renal form of PHA1 and analyzed NR3C2. The two patients had poor weight gain, and one was developmentally delayed. Genetic analysis identified one novel mutation (c.492_493insTT, p.Met166LeufsX8) and one previously reported mutation (p.R861X). The two produced a premature stop codon, resulting in haploinsufficiency of the MR. In conclusion, genetic analysis of NR3C2 is useful for diagnosis and planning therapeutic strategies.