The codon 213 of the 11β-hydroxysteroid dehydrogenase type 2 gene is a hot spot for mutations in apparent mineralocorticoid excess

In the kidney, the 11 beta-hydroxysteroid dehydrogenase type 2 enzyme (11 beta HSD2) inactivates glucocorticoids to their inactive ketoforms and thus prevents endogenous glucocorticoids from occupying the nonselective mineralocorticoid receptor in epithelial tissues. Several mutations have been described in the 11 beta HSD2 gene in the congenital syndrome of apparent mineralocorticoid excess. These mutations generate partially or completely inactive 11 beta HSD2 enzymes. In the present work, we describe an already known mutation in a new patient affected by apparent mineralocorticoid excess, which results in an arginine-to-cysteine mutation (R213C) in the 11 beta HSD2 enzyme. This mutation has been found in two other independent families. In vitro expression studies of this mutant provide evidence that the mutant protein is normally expressed, but its activity is abolished. The CGC-to-TGC (C-toT) transition at codon 213 can be considered a typical CpG-consequence mutation. The present finding suggests that the codon R213 of 11 beta HSD2 is a hot spot for mutations in this gene, as shown by the occurrence of an R213C point-mutation in several families unrelated to each other.