Two of three isozymes of<unk> R can catalyze the transformation of T to DHT, but it is only<unk> R2D that causes 46XY, DSD.<unk> R2 is encoded by the gene SRD5A2 which is located on the short arm of chromosome 2 and contains five exons and four introns.<unk> R2 consists of 254 amino acid residues with reported mutations at 67 of them with multiple different mutations at some residues. The first known mutation SRD5A2 was almost a complete deletion which was discovered from analysis of affected males in Papua New Guinean tribe. The majority of SRD5A2 mutations are missense mutations but small deletions, splice junction mutations, and gross deletions were also observed. Mutations result in a spectrum of activity effects ranging from destabilizing<unk> R2 to complete loss of activity. SRD5A2 mutations are inherited in an autosomal recessive pattern. Homozygous defects are more common than compound heterozygous ones. A phenotype-genotype correlation is not known to exist for many of the most common mutations, and affected males with the same<unk> R2 mutations have variable phenotypes suggesting other interacting genetic factors that determine phenotype.
5α-Reductase 2 deficiency
Isolated 17,20-lyase deficiency
17β-Hydroxysteroid dehydrogenase III deficiency
Aromatase deficiency
Cortisone reductase deficiency
Androgen-induced hermaphroditism
Multiple sulfatase deficiency
Gonadotropin-releasing hormone insensitivity