This information is provided by the National Institutes of Health (NIH) Genetic and Rare Diseases Information Center (GARD).
Methylmalonic acidemia with homocystinuria is an inherited disorder in which the body is unable to properly process certain nutrients from food including amino acids, lipids and cholesterol. People with this disorder have a combination of features from two separate conditions: methylmalonic acidemia and homocystinuria. When the condition begins early in life, babies have difficulty gaining weight (failure to thrive), feeding difficulties, and a pale appearance. Babies may also have weak muscle tone (hypotonia) and seizures. Most babies and children with this condition have an unusually small head size (microcephaly), intellectual disability and developmental delay. Less common features of the condition include eye problems and a blood disorder called megaloblastic anemia. When the disorder begins in adolescence or adulthood, the signs and symptoms usually include behavior and personality changes and cognitive problems (issues with learning, memory, perception etc). In some cases, abilities are lost, resulting in a decline of performance, memory and speech problems, dementia and lethargy.[12470
Methylmalonic acidemia with homocystinuria can be caused by mutations in one of several genes: MMACHC, MMADHC, LMBRD1, ABCD4, or HCFC1. Mutations in these genes account for the different types of the disorder, cblC, cblD, cblF, cblJ, and cblX, respectively. Although there is no cure for this conditions, treatment may include intramuscular injections of hydroxycobalamin, oral betaine, and folic acid.
For more information, visit GARD.