Based on the presence of a micropenis and the later onset of hyperpigmentation, along with failed ACTH stimulation test and XY karyotype, we suspected the diagnosis of mutations of NR0B1, CYP11A1, and STAR genes or familial glucocorticoid deficiency (FGD) (MC2R, MRAP, NNT, and AAAS). The gene discussed is MC2R; the disease is Micropenis.