NR0B1 and alternating hemiplegia of childhood: Congenital adrenal hypoplasia (adrenal hypoplasia congenita, AHC) is a rare condition characterized by an impaired development of the adrenal glands, caused by nuclear receptor variants that regulate both adrenal and reproductive function (DAX1 and Sf-1 variants) or multisystem intrauterine growth restriction (IUGR) syndromes.