Genetic disorders involving adrenal development.
[triple a syndrome]
The past decade has seen significant advances in our understanding of the genetic aetiology of several forms of adrenal failure that present in infancy or childhood. Several of these disorders affect adrenal development and are termed 'adrenal hypoplasia'. These conditions can be broadly divided into: (1) secondary forms of adrenal hypoplasia due to panhypopituitarism (e.g. HESX1, LHX4, SOX3) or abnormalities in ACTH synthesis (TPIT) or processing (e.g. POMC or PC1); (2) adrenal hypoplasia as part of an ACTH resistance syndrome [MC2R/ACTH receptor, MRAP, AAAS (triple A syndrome)], and (3) primary defects in the development of the adrenal gland itself (primary adrenal hypoplasia). Primary adrenal hypoplasia most commonly occurs in an X-linked form due to mutations in the nuclear receptor DAX1 (NR0B1) but can occur in a poorly understood recessive form or as part of the IMAGe (intrauterine growth retardation, metaphyseal dysplasia, adrenal hypoplasia, genitourinary anomalies) syndrome. Defining the molecular basis of these conditions can have significant clinical implications for management, counselling and presymptomatic diagnosis, as well as providing fascinating insight into normal and abnormal mechanisms of adrenal development in humans.
