Micropenis and the 5alpha-reductase-2 (SRD5A2) gene: mutation and V89L polymorphism analysis in 81 Japanese patients.

The results suggest that, in Japanese patients, micropenis can be caused by SRD5A2 gene mutations, especially by R227Q which has been shown to retain approximately 3.2% of normal enzyme activity and appears relatively frequent in Asian populations, and that V89L polymorphism is unlikely to raise the susceptibility to the development of micropanis.