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5-alpha reductase

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steroid-5-alpha-reductase, alpha polypeptide 1
Identifiers
Symbol(s) SRD5A1
Entrez 6715
OMIM 184753
RefSeq NM_001047
UniProt P18405
Other data
EC number 1.3.99.5
Locus Chr. 5 p15
steroid-5-alpha-reductase, alpha polypeptide 2
Identifiers
Symbol(s) SRD5A2
Entrez 6716
OMIM 607306
RefSeq NM_000348
UniProt P31213
Other data
EC number 1.3.99.5
Locus Chr. 2 p23

5-alpha reductase is an enzyme (EC 1.3.99.5) that converts testosterone, the male sex hormone, into dihydrotestosterone. There are two isoenzymes, steroid 5-alpha reductase 1 and 2 (SRD5A1 and SRD5A2). The second isoenzyme is deficient in 5-alpha-reductase deficiency which leads to a form of intersexualism.

Inhibition of 5-alpha reductase results in decreased produciton of DHT, increased levels of testosterone and possibly increased levels of estradiol. Gynecomastia is a possible side effect of 5-alpha reductase inhibition.

[edit] Genetics

SRD5A1 is located on chromosome 5p15, while SRD5A2 is located on 2p23.

[edit] Pharmacology

Finasteride inhibits the function of only one of the isoenzymes (type 1), while dutasteride inhibits both forms. These drugs are used in benign prostatic hyperplasia, prostate cancer and baldness (finasteride).

[edit] External

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