IEMbase 0028: CTH-related cystathionine gamma-lyase deficiency
Scope
| Field | Value |
|---|---|
| IEMbase ID | 28 |
| Nosology | 1.5.07.01 |
| Gene | CTH |
| External IDs | OMIM:219500 |
| Generated mapping | UNMAPPED; best fuzzy candidate Homocystinuria.yaml |
| Candidate DisMech targets | none currently valid |
| Review date | 2026-07-07 |
IEMbase phenotype signal
IEMbase represents cystathionine gamma-lyase deficiency/cystathioninuria as a
biochemical condition with no clinical significance. The only characteristic
clinical row is No clinical significance across all age bands.
The biochemical signal is high plasma cystathionine, very high plasma/urinary cystathionine, low methionine-to-cystathionine ratio, normal cysteine, and normal-to-mildly high total homocysteine. No treatments are listed and treatability is unknown.
DisMech phenotype coverage
There is no current DisMech entry for CTH deficiency or cystathioninuria. The
best fuzzy candidate, Homocystinuria.yaml, should be rejected. CBS-deficient
homocystinuria has low cystathionine, marked hyperhomocystinemia, elevated or
variable methionine, and a severe ocular/skeletal/vascular phenotype. CTH
deficiency has the opposite cystathionine signal and is represented by IEMbase
as clinically insignificant.
Concordance and completeness
Judgement: generated status is correctly unmapped. The fuzzy homocystinuria candidate is mechanistically misleading despite pathway proximity.
There is no local DisMech coverage to compare for phenotype completeness. If a future entry is created, it should be framed as a mostly biochemical cystathioninuria record unless stronger clinical evidence is added.
Curation actions
- Do not map this record to
Homocystinuria.yaml. - If curated, preserve the low-clinical-significance judgement and avoid importing CBS-deficiency complications.
- The key differentiator is high cystathionine in CTH deficiency versus low cystathionine in CBS deficiency.