IEMbase 0084: TCN1-related haptocorrin deficiency
Scope
| Field | Value |
|---|---|
| IEMbase ID | 84 |
| Nosology | 21.9.04.01 |
| Gene | TCN1 |
| External IDs | OMIM:193090 |
| Generated mapping | UNMAPPED |
| Candidate DisMech targets | Best fuzzy candidate Pyruvate_Dehydrogenase_Deficiency.yaml#E3-binding protein deficiency |
| Review date | 2026-07-07 |
IEMbase phenotype signal
IEMbase represents this as TCN1-related haptocorrin deficiency, with alternate labels transcobalamin I deficiency, cobalamin R binder protein deficiency, and HCD. Inheritance is recorded as autosomal dominant and autosomal recessive. Treatability is marked unknown.
The characteristic biochemical signal is abnormal vitamin B12/cobalamin in serum or plasma.
The characteristic clinical row is "no consistent clinical picture."
No treatment rows are present in the cached IEMbase record.
DisMech phenotype coverage
No valid local DisMech target was found for TCN1 or haptocorrin deficiency.
The local Inborn_Disorder_of_Cobalamin_Metabolism_and_Transport.yaml entry
covers transcobalamin II deficiency (TCN2), LMBRD1/cblF, ABCD4/cblJ, and
intracellular cobalamin complementation groups, but it does not model TCN1 or
haptocorrin deficiency.
The best fuzzy candidate, Pyruvate_Dehydrogenase_Deficiency.yaml#E3-binding
protein deficiency, is a false positive. PDH E3-binding protein deficiency is a
PDHX/pyruvate metabolism disorder, not a cobalamin-binding protein phenotype.
Concordance and completeness
Judgement: local gap, but scope review is needed before prioritizing a full disease entry.
Unlike TCN2 deficiency, IEMbase itself records no consistent clinical picture for TCN1 deficiency. This may be better handled as a low-priority cobalamin transport/biomarker note unless future evidence supports a clear disease mechanism and phenotype.
Curation actions
- Keep this IEMbase record unmapped for now.
- Do not map it to TCN2 deficiency or PDH E3-binding protein deficiency.
- If the cobalamin transport area is expanded, decide whether TCN1 belongs as a disease entry, subtype, or scoped-out biochemical trait.