 Most cases of familial glucocorticoid and mineralocorticoid deficiency are caused by mutations interrupting steroidogenesis such as 21- hydroxylase deficiency. Recently, nicotinamide nucleotide transhydrogenase NNT mutations were found to cause isolated glucocorticoid deficiency or combined mineralocorticoid and glucocorticoid deficiency through decreased detoxification of reactive oxygen species ROS in adrenocortical cells. 