CYB5A and primary adrenal insufficiency: As genes involved in early steps of steroid biosynthesis, such as StAR, cytochrome P450 side-chain cleavage (CYP11A1), HSD3B2, CYP17A1, POR, cytochrome b5 (CYB5) are common to both adrenal and gonadal steroidogenesis, they may manifest at birth with primary adrenal insufficiency and 46,XY undervirilization due to steroid hormone deficiencies of prenatal onset.