Methylcobalamin deficiency, cbl E complementation type

Methylcobalamin Deficiency, cblE Complementation Type is a rare genetic disorder characterized by a deficiency in methylcobalamin, a form of vitamin B12 that is crucial for maintaining healthy nerve cells and creating DNA. This condition falls under the broader category of cobalamin metabolism disorders, specifically the cblE complementation type. It is caused by mutations in the MMADHC gene, which plays a significant role in the intracellular processing of vitamin B12 into its coenzyme forms, including methylcobalamin.

Symptoms

The symptoms of Methylcobalamin Deficiency, cblE Complementation Type, can vary widely among affected individuals but generally include developmental delay, neurological impairment, megaloblastic anemia, and homocystinuria. Neurological symptoms may range from mild to severe and can include muscle weakness, problems with movement and balance, neuropathy, and intellectual disability. The onset of symptoms typically occurs in infancy or early childhood.

Diagnosis

Diagnosis of Methylcobalamin Deficiency, cblE Complementation Type, involves a combination of clinical evaluation and laboratory testing. Elevated levels of homocysteine in the blood and urine, along with decreased levels of methionine, are indicative of this condition. Genetic testing for mutations in the MMADHC gene confirms the diagnosis.

Treatment

Treatment focuses on managing symptoms and may include supplementation with hydroxocobalamin, a form of vitamin B12, and betaine, which helps reduce homocysteine levels. Early diagnosis and treatment are crucial for improving outcomes and preventing complications. Regular monitoring and supportive care for developmental and neurological issues are also important aspects of management.

Epidemiology

Methylcobalamin Deficiency, cblE Complementation Type, is an extremely rare disorder. The exact prevalence is unknown due to its rarity and the possibility of undiagnosed cases.

Genetics

The condition is inherited in an autosomal recessive manner, meaning that an individual must inherit two copies of the mutated gene, one from each parent, to be affected. Carriers, who have only one copy of the mutation, typically do not show symptoms of the disease.

See Also

• Vitamin B12 Deficiency
• Megaloblastic Anemia
• Homocystinuria
• Genetic Disorders
• Metabolic Disorders

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