In affected members of several families segregating glucocorticoid deficiency, Metherell et al. (2005) identified homozygous mutations in the MRAP gene (609196.0001-609196.0007), encoding a 19-kD single transmembrane domain protein that interacts with MC2R and may have a role in ... In affected members of several families segregating glucocorticoid deficiency, Metherell et al. (2005) identified homozygous mutations in the MRAP gene (609196.0001-609196.0007), encoding a 19-kD single transmembrane domain protein that interacts with MC2R and may have a role in the trafficking of MC2R from the endoplasmic reticulum to the cell surface.