Here I present: “Pseudovaginal Perineoscrotal Hypospadias”, MendelianInheritance in Man’, 1966. 假性陰道会陰性下骶。
INTRODUCTION.
Hypospadias is a common malformation in fetal development of the penis in which the urethra does not open from its usual location on the head of the penis. It is the second-most common birth defect of the male reproductive system.
The human gene SRD5A2 encodes the 3-oxo-5α-steroid 4-dehydrogenase 2 enzyme, also known as 5α-reductase type-2 (5αR2), one of three isozymes of 5α-reductase. 5αR2 catalyzes the conversion of the male sex hormone testosterone into the more potent androgen, dihydrotestosterone.
5αR2 is a microsomal protein expressed at high levels in androgen-sensitive tissues such as the prostate. The 5αR2 enzyme is Enzyme Commission Number EC# 1.3.99.5 classification. Deficiencies in 5αR2 activity of the can lead to a condition known as 5α-reductase type-2 deficiency, which is a cause of 46,XY DSD that presents as atypical male genitalia.
There is evidence pseudovaginal perineoscrotal hypospadias (PPSH) is caused by homozygous or compound heterozygous mutation in the steroid 5-alpha-reductase-2 gene (SRD5A2) on cytogenetic location 2p23.1 and genomic coordinates 2:31,522,480-31,663,009 . The screenshot of the SRD5A2 gene 140,530 bp (base pairs) of DNA sequence length is shown BELOW. Nine (9) other genes besides SRD5A2 in 2p23.1 cytogenetic location are listed BENEATH. 
| Coordinate | Symbol | Genomic Name. |
| 2:30,886,782 | GALNT14 | Galnac Transferase14 |
| 2:31,173,056 | CAPN14 | Calpain 14 |
| 2:31,234,152 | EHD3 | EH domain-containing 3 |
| 2:31,334,321 | XDH | Xanthine dehydrogenase |
| 2:31,522,480 | SRD5A2 | Steroid-5-alpha-reductase |
| 2:31,800,001 | CANDF1 | Candidiasis, familial, 1 |
| 2:31,867,823 | MEMO1 | Mediator of cell motility 1 |
| 2:32,011,649 | DPY30 | DPY30 histone methyltransferase |
| 2:32,063,556 | SPAST | Spastin |
| 2:32,165,864 | SLC30A6 | Solute carrier family 30 |
