Pathogenic variants of the MC2R gene that produce an aberrant protein can downregulate the cortisol synthesis pathway and abolish ACTH stimulation; defects in this pathway could lead to various clinical manifestations of FGD, including hyperpigmentation, hypoglycemia, eczema, failure to thrive, jaundice, and increased susceptibility to infection [20–22]. Here, POMC is linked to Failure to thrive.