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Methylmalonic acidemia with homocystinuria, type cblC
cblC type methylmalonic acidemia with homocystinuria is a form of methylmalonic acidemia with homocystinuria (see this term), an inborn error of vitamin B12 (cobalamin) metabolism characterized by megaloblastic anemia, lethargy, failure to thrive, developmental delay, intellectual deficit and seizures.
ORPHA:79282Classification level: Subtype of disorder
- CblC defect
- Cobalamin C defect
- Combined defect in adenosylcobalamin and methylcobalamin synthesis, type cblC
- Methylmalonic aciduria with homocystinuria, type cblC
- Prevalence: Unknown
- Inheritance: Autosomal recessive
- Age of onset: All ages
- ICD-10: D58.8
- OMIM: 277400
- UMLS: -
- MeSH: -
- GARD: 12128
- MedDRA: -
To date, over 500 cases of cblC have been reported, making it the most frequent type of methylmalonic acidemia with homocystinuria.
The disease typically presents with failure to thrive, acute neurological deterioration, intellectual deficit, lethargy, seizures, microcephaly, a salt-and-pepper retinopathy, and signs of megaloblastic anemia (pallor, fatigue, anorexia). Severe brain abnormalities including hydrocephalus, white matter abnormalities, cerebral atrophy, and unusual basal ganglia lesions are common. Onset of the disorder can be early (infantile) or late (juvenile or adult), with the late-onset form characterized by ataxia, dementia and psychosis.
cblC type methylmalonic acidemia with homocystinuria is caused by mutations in the MMACHC gene (1p36.3) and is transmitted in an autosomal recessive manner.
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