Two Qatari siblings with cystic fibrosis and apparent mineralocorticoid excess.

Abstract

Cystic fibrosis (CF) and apparent mineralocorticoid excess (AME) syndrome are both autosomal recessive disorders that result from mutations of specific identified genes for each condition. CF is caused by defects in the Cystic fibrosis trans membrane conductance regulator (CFTR) gene which encodes for a protein that functions as a chloride channel and regulates the flow of other ions across the apical surface of epithelial cells. AME is due to the deficiency of 11β-hydroxysteroid dehydrogenase type 2 enzyme (11βHSD2), which is responsible for the peripheral inactivation of cortisol to cortisone. Cortisol excess stimulates the mineralocoritoid receptors (MR) resulting in intense sodium retention, hypokalemia and hypertension. We report on a consanguineous Arab family, in which two sibs inherited both CF and AME. Gene testing for AME revealed previously unreported mutation in the 11βHSD2 gene. This report draws attention to the importance of recognizing the possibility of two recessive disorders in the same child in complex consanguineous families. Moreover, it provides a unique opportunity to highlight the implications of the coexistence of two genetic disorders on patient care and genetic counseling of the family.