Inborn errors of steroid metabolism

An inborn error of steroid metabolism is an inborn error of metabolism due to defects in steroid metabolism. A variety of conditions of abnormal steroidogenesis exist due to genetic mutations in the steroidogenic enzymes involved in the process, of which include: 20,22-Desmolase (P450scc) deficiency: blocks production of all steroid hormones from cholesterol 3β-Hydroxysteroid dehydrogenase 2 deficiency: impairs progestogen and androgen metabolism; prevents the synthesis of estrogens, glucocorticoids, and mineralocorticoids; causes androgen deficiency in males and androgen excess in females Combined 17α-hydroxylase/17,20-lyase deficiency: impairs progestogen metabolism; prevents androgen, estrogen, and glucocorticoid synthesis; causes mineralocorticoid excess Cytochrome P450 oxidoreductase deficiency: prevents production of numerous but not all sex steroids, as well as other metabolic reactions Isolated 17,20-lyase deficiency: prevents androgen and estrogen synthesis. Cytochrome b5 deficiency: subtype of isolated 17,20-lyase deficiency; additionally results in elevated methemoglobin and/or methemoglobinemia 17β-Hydroxysteroid dehydrogenase 3 deficiency: impairs androgen and estrogen metabolism; results in androgen deficiency in males and androgen excess and estrogen deficiency in females 5α-Reductase 2 deficiency: prevents the conversion of testosterone to dihydrotestosterone; causes androgen deficiency in males Aromatase deficiency: prevents estrogen synthesis; causes androgen excess in females Aromatase excess: causes excessive conversion of androgens to estrogens; results in estrogen excess in both sexes and androgen deficiency in males.