homocystinuria without methylmalonic aciduria
Findings
No curated finding names homocystinuria without methylmalonic aciduria yet. Everything below is reference data from Mondo, HPO and GenCC, not evidence about what affects it.
Definition
Homocystinuria without methylmalonic aciduria is an inborn error of vitamin B12 (cobalamin) metabolism characterized by megaloblastic anemia, encephalopathy and, sometimes, developmental delay, and associated with homocystinuria and hyperhomocysteinemia. There are three types of homocystinuria without methylmalonic aciduria; cblE, cblG and cblD-variant 1 (cblDv1).
Definition from the Mondo Disease Ontology (MONDO:0018964), read 2026-09-29. CC BY 4.0.
Features
30 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.
- HomocystinuriaHPOHP:0002156
- Very frequent (80% to 99% of cases)
- Cerebral cortical atrophyHPOHP:0002120
- Frequent (30% to 79% of cases)
- DrowsinessHPOHP:0002329
- Frequent (30% to 79% of cases)
- EncephalopathyHPOHP:0001298
- Frequent (30% to 79% of cases)
- Failure to thriveHPOHP:0001508
- Frequent (30% to 79% of cases)
- Feeding difficultiesHPOHP:0011968
- Frequent (30% to 79% of cases)
- Global developmental delay
Show the remaining 18
- PsychosisHPOHP:0000709
- Frequent (30% to 79% of cases)
- RetinopathyHPOHP:0000488
- Frequent (30% to 79% of cases)
- SeizureHPOHP:0001250
- Frequent (30% to 79% of cases)
- StrabismusHPOHP:0000486
- Frequent (30% to 79% of cases)
- AtaxiaHPOHP:0001251
- Occasional (5% to 29% of cases)
- Atypical behaviorHPOHP:0000708
- Occasional (5% to 29% of cases)
Where it sits
Other names
2 names
Resolves to: homocystinuria without methylmalonic aciduria
- Also called
- functional methionine synthase deficiencymethylcobalamin deficiency