IEMbase 0127: SRD5A2-related Steroid 5-alpha-reductase type 2 deficiency
Scope
| Field | Value |
|---|---|
| IEMbase ID | 127 |
| Nosology | 24.2.22.01 |
| Gene | SRD5A2 |
| External IDs | OMIM:264600; ORPHA:1331 |
| Generated mapping | CANDIDATE, medium confidence |
| Candidate DisMech targets | 46_XY_DSD_Due_to_5_Alpha_Reductase_2_Deficiency.yaml |
| Review date | 2026-07-07 |
IEMbase phenotype signal
IEMbase represents this as SRD5A2-related steroid 5-alpha-reductase type 2 deficiency, with alternate labels pseudovaginal perineoscrotal hypospadias and 5alpha reductase deficiency. Treatability is marked unknown.
The characteristic biochemical rows are decreased DHT and increased testosterone/dihydrotestosterone ratio. Clinical rows include a reduced 5-alpha/5-beta urinary metabolite ratio and virilization at puberty. No treatment rows are listed.
DisMech phenotype coverage
46_XY_DSD_Due_to_5_Alpha_Reductase_2_Deficiency.yaml is the correct local
target. It describes biallelic SRD5A2 loss of function, impaired
testosterone-to-DHT conversion, incomplete intrauterine masculinization in
46,XY individuals, and possible pubertal virilization.
The local phenotype coverage includes cryptorchidism, ambiguous male genitalia, small or bifid scrotum, perineal hypospadias, micropenis, decreased fertility, urogenital sinus anomaly, pubertal virilization, and voice change. Biochemical coverage includes DHT and testosterone-to-DHT ratio. Treatments include gonadectomy and orchiopexy/testis descent.
Concordance and completeness
Judgement: accept the generated candidate as the correct mapping.
The candidate status appears to reflect lexical uncertainty rather than a real scope mismatch. IEMbase and DisMech agree on SRD5A2, DHT deficiency, elevated testosterone-to-DHT ratio, 46,XY undervirilization context, and pubertal virilization. IEMbase adds the urinary 5-alpha/5-beta metabolite ratio, which is useful diagnostic granularity not yet obvious in the local file.
Curation actions
- Promote the generated candidate to a correct mapping to
46_XY_DSD_Due_to_5_Alpha_Reductase_2_Deficiency.yaml. - Consider adding the urinary 5-alpha/5-beta metabolite ratio as a subtype-specific diagnostic biochemical row.
- No new standalone disease target is needed.