17 alpha-hydroxylase deficiency overview
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Mehrian Jafarizade, M.D [2]
Overview
Historical Perspective
17 alpha-hydroxylase deficiency was first reported by Dr. Edward G. Biglieri, an American endocrinologist, in 1963-1966 following publication of a case report.
Classification
17 alpha-hydroxylase deficiency may be classified into two types, based on clinical findings: partial form and severe form.
Pathophysiology
17 alpha-hydroxylase deficiency is an uncommon form of congenital adrenal hyperplasia resulting from a defect in the gene CYP17A1, which encodes for the enzyme 17 alpha-hydroxylase and 17,20-lyase. 17 alpha-hydroxylase deficiency is transmitted in an autosomal recessive pattern. Mineralocorticoid excess and lack of androgens are two main features in this disease.
Causes
Mutations in the CYP17A1 gene cause 17 alpha-hydroxylase deficiency. This gene is located on chromosome 10.
Differential Diagnosis
17 alpha-hydroxylase deficiency must be differentiated from diseases with primary amenorrhea and female external genitalia. Some of these causes include pregnancy, androgen insensitivity syndrome, 3beta-hydroxysteroid dehydrogenase type 2 deficiency, 17-alpha-hydroxylase deficiency, gonadal dysgenesis, testicular regression syndrome, LH receptor defects, 5-alpha-reductase type 2 deficiency, mullerian agenesis, primary ovarian insufficiency, hypogonadotropic hypogonadism and turner syndrome.