MCM4 and Aarskog-Scott syndrome, X-linked: Although half of the FGD cases are caused by mutations in genes involved in (i) the ACTH signaling–steroidogenic pathway (MC2R, MRAP, STAR), (ii) the replicative complex critical for normal DNA replication and genome stability (MCM4), and (iii) antioxidant system (TXNRD2) [19], no mutations have been found in the rest of the cases, suggesting the presence of hitherto unidentified responsible genes in FGD.