Apparent Mineralocorticoid Excess by a Novel Mutation and Epigenetic Modulation by HSD11B2 Promoter Methylation

Context: Apparent mineralocorticoid excess (AME) is a rare autosomal recessive disease resulting from mutations within the hydroxysteroid (11β-dehydrogenase2 [HSD11B2]) gene causing a prominent mineralocorticoid receptor activation by cortisol and hypokalemic low renin hypertension as the main clinical feature. Objective: The objective of the study was to characterize AME for possible novel HSD11B2 mutations and to define the role of HSD11B2 promoter methylation in the phenotypic expression of the disease. Subjects: Two proband brothers and 10 relatives participated in the study. Methods: Peripheral blood mononuclear cell DNA was used for HSD11B2 exon sequencing, and a new predicted structure of 11β-hydroxysteroid dehydrogenase type 2 was generated by an in silico three-dimensional modeling. Promoter methylation was determined by bisulfite pyrosequencing. Urinary tetrahydrocortisol plus allotetrahydrocortisol to tetrahydrocortisone ratio, a surrogate marker of 11β-hydroxysteroid dehydrogenase type 2 activ...