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21-hydroxylase deficiency

Other Names for this Disease
  • 21 hydroxylase deficiency
  • Congenital adrenal hyperplasia due to 21-hydroxylase deficiency
  • CYP21 deficiency
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21-hydroxylase-deficiency is a genetic disorder of cortisol biosynthesis. It is caused by mutations in the human 21-hydroxylase gene (CYP21A2).[1] Symptoms of 21-hydroxylase deficiency vary, but can involve salt-wasting crises in infants; ambiguous genitalia in female infants; excessive hair, deep voice, abnormal periods, no periods, and fertility problems in older girls and women; early development of masculine features in boys; and shorter than average adult height, acne, and blood pressure problems.[2]
Last updated: 2/22/2010


  1. Stewart PM. The adrenal cortex. In: Kronenberg HM, Melmed S, Polonsky KS, Larsen PR, eds. Kronenberg: Williams Textbook of Endocrinology. 11th ed. Philadelphia, PA: Saunders; 2008..
  2. Congenital Adrenal Hyperplasia: What It Is and How It's Treated. American Academy of Family Physicians. 2006; Accessed 4/4/2008.
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Basic Information

  • The Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) provides information related to the health of children, adults, and families. Click on the link to view information on this topic. 
  • The Genetic Alliance is an international coalition comprised of more than 600 advocacy, research and health care organizations representing millions of individuals with genetic conditions. Click on the link to view information on this topic.
  • Genetics Home Reference (GHR) contains information on 21-hydroxylase deficiency. This website is maintained by the National Library of Medicine.
  • The National Organization for Rare Disorders (NORD) is a federation of more than 130 nonprofit voluntary health organizations serving people with rare disorders. Click on the link to view information on this topic.

In Depth Information

  • Medscape Reference provides information on this topic. Click on the link to view this information. You may need to register to view the medical textbook, but registration is free.
  • The Online Mendelian Inheritance in Man (OMIM) is an catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
  • PubMed is a searchable database of medical literature and lists journal articles that discuss 21-hydroxylase deficiency. Click on the link to view a sample search on this topic.