17-beta-hydroxysteroid dehydrogenase deficiency overview
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Abdulkerim Yassin, M.B.B.S[2]
Synonyms and keywords: 17-beta hydroxysteroid dehydrogenase III deficiency, 17-ketosteroid reductase deficiency of testis, 17-KSR deficiency, Neutral 17-beta-hydroxysteroid oxidoreductase deficiency, Male Pseudohermaphroditism with gynecomastia, Testosterone 17-beta-dehydrogenase deficiency
Overview
17-beta-hydroxysteroid dehydrogenase deficiency is a rare autososmal recessive developmental disorder that affects male sexual development. Individuals with this condition are genetically male and have testes, but do not produce enough testosterone. The synthesis of testestrone is impaired and the levels in the serum is low which disrupts the formation of external male genitalia before birth. The affected individual is male with XY chromosomes with phenotype female or ambigiounal external genitalia which is the external genitalia do not look clearly male or clearly female , characterized by clitoromegaly, posterior labioscrotal fusion and perineal blind vaginal pouch. Testes are located in inguinal or in the labioscrotal folds. The internal urogenital tract (epididymides, vasa deferentia, seminal vesicles, ejaculatory ducts) is well developed; prostate and Müllerian structures are absent. Majority of cases do not present until puberty, at which time peripheral conversion of androgen precursors causes ongoing virilization. Although some patients with less severe defects are brought up as males, affected males are usually raised as girls. During puberty, the affected patients present with either primary amenorrhea or sudden onset of virilization and most of the affected individuals develop male secondary sex characteristics, such as increased muscle mass, deepening of the voice, and development of male pattern body hair. HSD17B3 gene mutations result in a 17-beta hydroxysteroid dehydrogenase 3 enzyme with decrease or no activity, reducing production of testosterone from androstenedione. Genetic analysis can confirm the diagnosis. Gonadectomy is recommended to prevent continuous virilization if a female gender identity is established. The risk of testicular neoplasia has not been determined, a point which should be discussed if patients choose to transition into a male gender role. All affected people with the disease are infertile.
Historical Perspectives
- 17 beta hydroxysteroid dehydrogenase III deficiency is initially described in 1971 by Saez and his colleagues.
Classification
- No sufficient data for classification of 17 beta hydroxysteroid dehydrogenase deficiency.
Pathophysiology
- 17-beta-hydroxysteroid dehydrogenase deficiency-3 is biochemically characterized by decreased levels of testosterone and increased levels of androstenedione as a result of the defect in conversion of androstenedione into testosterone.
Causes
- HSD17B3 gene mutation causes 17-beta hydroxysteroid dehydrogenase deficiency results a decrease in testosterones production. The reduction of testosterones affects the development of male reproductive tract which results phenotypically female or ambiguous external genitalia.
Differentiating 17 Beta hydroxysteroid Dehydrogenase Deficiency from Other Diseases
- 17 beta hydroxysteroid dehydrogenase deficiency should be differentiated from other diseases that cause ambiguous genitalia.
Epidemiology and Demographics
- Although the precise incidence of 17βHSD-3 deficiency is unknown, a recent study from the Netherlands estimated the incidence around 1 in 147,000 newborns, with a calculated heterozygote frequency of 1 in 135.