methylmalonic aciduria and homocystinuria
Findings
No curated finding names methylmalonic aciduria and homocystinuria yet. Everything below is reference data from Mondo, HPO and GenCC, not evidence about what affects it.
Definition
An inborn error of vitamin B12 (cobalamin) metabolism characterized by megaloblastic anemia, lethargy, failure to thrive, developmental delay, intellectual deficit and seizures. There are four complementation classes of cobalamin defects (cblC, cblD, cblF and cblJ) that are responsible for methylmalonic acidemia - homocystinuria (methylmalonic acidemia - homocystinuria cblC, cblD cblF and cblJ).
Definition from the Mondo Disease Ontology (MONDO:0016826), read 2026-09-29. CC BY 4.0.
Features
20 features
What the disease is reported to present with, and how often among people who have it — never how often a feature means the disease. HPO, annotations 2026-09-02.
- AmblyopiaHPOHP:0000646
- Very frequent (80% to 99% of cases)
- Failure to thriveHPOHP:0001508
- Very frequent (80% to 99% of cases)
- FatigueHPOHP:0012378
- Very frequent (80% to 99% of cases)
- Feeding difficultiesHPOHP:0011968
- Very frequent (80% to 99% of cases)
- Global developmental delayHPOHP:0001263
- Very frequent (80% to 99% of cases)
- HypotoniaHPOHP:0001252
- Very frequent (80% to 99% of cases)
- Intellectual disability
Show the remaining 8
- Abnormal cardiovascular system morphologyHPOHP:0030680
- Frequent (30% to 79% of cases)
- Abnormality of movementHPOHP:0100022
- Frequent (30% to 79% of cases)
- Atypical behaviorHPOHP:0000708
- Frequent (30% to 79% of cases)
- Gait disturbanceHPOHP:0001288
- Frequent (30% to 79% of cases)
- HydrocephalusHPOHP:0000238
- Frequent (30% to 79% of cases)
- Skin rashHPOHP:0000988
- Occasional (5% to 29% of cases)
Genes
2 genes
Germline variants in the gene encoding each protein, as classified by GenCC submitters, each in their own words. Limited, disputed and refuted submissions are listed too.
Where it sits
- A kind of
- Narrower terms (6)
- methylmalonic acidemia with homocystinuria, type cblJ
- methylmalonic acidemia with homocystinuria, type cblX
- methylmalonic aciduria and homocystinuria type cblC
- methylmalonic aciduria and homocystinuria type cblD
- methylmalonic aciduria and homocystinuria type cblF
- methylmalonic aciduria and homocystinuria, cb1L type
Other names
2 names
Resolves to: methylmalonic aciduria and homocystinuria
- Also called
- combined defect in adenosylcobalamin and methylcobalamin synthesismethylmalonic aciduria with homocystinuria