A novel nonsense mutation of the mineralocorticoid receptor gene in the renal form of pseudohypoaldosteronism type 1.

Pseudohypoaldosteronism type 1 (PHA1) is a rare congenital disease characterized by salt loss resistant to mineralocorticoids. Most patients are identified by failure to thrive or poor weight gain in early infancy. Plasma renin activity and aldosterone are markedly elevated. PHA1 is caused by mutations in genes encoding either subunits of the amiloride-sensitive epithelial sodium channel (ENaC) or mineralocorticoid receptor (MR) inherited in an autosomal recessive or dominant form, respectively. Patients with the autosomal dominant form of PHA1 show gradual clinical improvement with advancing age; however, the reason for this remains unclear. We report the renal form of PHA1 in a Japanese family. Polymerase chain reaction and direct sequencing revealed a heterozygous nonsense mutation changing codon 861 Arg (CGA) to stop (TGA) in the index patient. Segregation analysis revealed an identical mutation in the patient's father and older sister. Inheritance in this case is assumed to be of the autosomal dominant type.