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Cytochrome P450 21A2 (CYP21A2) testing in congenital adrenal hyperplasia. Lansdale: HAYES, Inc.. Genetic Testing Publication. 2012

Congenital adrenal hyperplasia (CAH) resulting from 21-hydroxylase deficiency (21-OHD) is an autosomal recessive disorder of steroid metabolism that occurs in 1 in 10,000 to 1 in 18,000 live births. As a result of this enzyme deficiency, affected individuals exhibit increased production of androgens and potentially decreased production of cortisol and aldosterone. Three different phenotypes may occur as a result of 21-OHD, each reflecting the various degrees of enzyme deficiency and resulting hormonal imbalances. The classic, salt-wasting type of CAH is characterized by a severe deficiency of cortisol and aldosterone and overproduction of androgens, leading to prenatal virilization and ambiguous genitalia in females, and salt-losing crises and adrenal gland enlargement in both males and females. The salt-losing crises may be fatal if untreated. The features of the classic simple virilizing form of CAH include variable degrees of virilization (such as ambiguous genitalia or clitoral enlargement), hirsutism (excessive hair growth in the androgen-sensitive areas of the body, such as the face), and menstrual irregularities in females, and early puberty, severe acne, advanced bone age, and fertility problems in both sexes. Saltwasting does not occur in this type of CAH. The nonclassic form of CAH is characterized by early puberty, severe acne, hirsutism, menstrual irregularities, and fertility problems; both males and females with this type of CAH have normal-appearing genitalia at birth. Individuals with 21-OHD CAH have the condition as a result of variants involving CYP21A2, the gene encoding the 21-hydroxylase (21-OH) enzyme located on chromosome 6 at band p21.3. The presence of a highly homologous but inactive pseudogene near CYP21A2 frequently leads to gene conversion events (when a segment of one gene is transferred to a second gene) and partial or whole-gene deletions or duplications involving the CYP21A2 locus. The pseudogene, designated CYP21A2P, contains at least 15 sequence variants that, when transferred to the CYP21A2 gene by gene conversion, are disease-causing alleles. The standard protocol for diagnosing 21-OHD CAH includes an analysis of 17-hydroxyprogesterone (17-OHP) concentrations and an adrenocorticotropin hormone (ACTH) stimulation test. The treatment of 21-OHD CAH often includes glucocorticoid replacement therapy and oral contraceptives in women with menstrual irregularities. Dexamethasone has also been used for the prenatal treatment of fetuses at risk of virilization. Administration of dexamethasone is typically performed prior to 9 weeks gestation and is discontinued if the fetus is found to be unaffected by prenatal diagnosis or is found to be male

The report may be purchased from:http://www.hayesinc.com/hayes/crd/?crd=13761

Subject indexing assigned by CRD

Adrenal Hyperplasia, Congenitals; Genetic Testing; Steroid 21-Hydroxylase

English

United States

An English language summary is available.

HAYES, Inc., 157 S. Broad Street, Suite 200, Lansdale, PA 19446, USA. Tel: 215 855 0615; Fax: 215 855 5218 Email: hayesinfo@hayesinc.com

32012000578

17/08/2012