MMACHC

Methylmalonic aciduria and homocystinuria, cobalamin C (cblC) type, commonly referred to as MMACHC, is a rare genetic disorder that affects the body's ability to process certain parts of proteins and fats. This condition is part of a group of disorders known as cobalamin C deficiency. MMACHC is caused by mutations in the MMACHC gene, which plays a crucial role in the metabolism of vitamin B12 (cobalamin). The disorder is characterized by the accumulation of methylmalonic acid and homocysteine in the blood, which can lead to a variety of health problems.

Symptoms

The symptoms of MMACHC can vary widely among affected individuals. They may include developmental delay, intellectual disability, failure to thrive, microcephaly (small head size), megaloblastic anemia, feeding difficulties, and visual impairment. Neurological symptoms such as seizures, hypotonia (reduced muscle tone), and ataxia (lack of muscle coordination) can also occur. The severity of symptoms can range from mild to life-threatening, and they can appear anytime from infancy to adulthood.

Causes

MMACHC is caused by mutations in the MMACHC gene on chromosome 1p34.1. This gene is essential for the proper processing of vitamin B12, which is necessary for the metabolism of fats and proteins. Mutations in the MMACHC gene lead to deficient activity of methylmalonyl-CoA mutase and methionine synthase, two enzymes that require derivatives of vitamin B12 as cofactors. As a result, toxic levels of methylmalonic acid and homocysteine accumulate in the body.

Diagnosis

Diagnosis of MMACHC typically involves a combination of clinical evaluation, family history, and laboratory tests. Elevated levels of methylmalonic acid and homocysteine in the blood and urine are indicative of the disorder. Genetic testing can confirm a diagnosis by identifying mutations in the MMACHC gene.

Treatment

There is no cure for MMACHC, but treatment is available to manage symptoms and prevent complications. Treatment strategies may include dietary restrictions, supplementation with hydroxocobalamin (a form of vitamin B12), betaine, folate, and L-carnitine. Regular monitoring and supportive care for developmental, neurological, and visual problems are also important aspects of management.

Prognosis

The prognosis for individuals with MMACHC varies depending on the severity of symptoms and the timing of diagnosis and treatment initiation. Early diagnosis and intervention can improve outcomes and reduce the risk of severe complications.

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Source: Data courtesy of the U.S. National Library of Medicine. Since the data might have changed, please query MeSH on MMACHC for any updates.

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