TY - CHAP M1 - Book, Section TI - Congenital Adrenal Hyperplasia A1 - Parsa, Alan A. A1 - Lekarev, Oksana A1 - New, Maria I. A1 - Yau, Mabel A1 - Khattab, Ahmed A2 - Murray, Michael F. A2 - Babyatsky, Mark W. A2 - Giovanni, Monica A. A2 - Alkuraya, Fowzan S. A2 - Stewart, Douglas R. Y1 - 2014 N1 - T2 - Clinical Genomics: Practical Applications in Adult Patient Care AB - Disease summary:Congenital adrenal hyperplasia (CAH) is a group of autosomal recessive inherited disorders of steroidal biosynthesis caused by a variety of enzymatic defects (Fig. 64-1).Most cases of CAH can be accounted for by deficiencies in 21-hydroxylase (21-GHO): 90% to 95% of cases and 11β-hydroxylase (OHO): 3% to 8%.Deficiencies in 21-hydroxylase and 11β-hydroxylase cause decreased cortisol production, that lead to a lack of negative inhibition of adrenocorticotropic hormone (ACTH) and oversecretion of ACTH. This increase in ACTH drives the adrenal glands to attempt to produce more cortisol but this increase is blocked by enzyme deficiencies. Adrenal precursors are thus shunted into the androgen pathway resulting in increased androgen synthesis, which does not require these enzymes.Phenotypes can range widely depending on the degree of enzyme deficiency.Hyperandrogenism is a key feature seen in 21-OHD and 11β-OHD.Hereditary basis:These are autosomal recessive genetic disorders; thus both parents are typically carriers of CYP21A2 or affected with 21-hydroxylase deficiency for the fetus to be affected.Though less common, new mutations can arise in CYP21A2.Differential diagnosis:In 46,XX, maternal androgen exposure, P450 oxoreductase deficiency (POR), ovotesticular disorder of sexual differentiation (DSD), mixed gonadal dysgenesisIn 46,XY, incomplete androgenization of genitals, 5α-reductase deficiency, nonclassic StAR SN - PB - McGraw-Hill Education CY - New York, NY Y2 - 2024/03/29 UR - accessmedicine.mhmedical.com/content.aspx?aid=1102701753 ER -