This information is provided by the National Institutes of Health (NIH) Genetic and Rare Diseases Information Center (GARD).
3-methylcrotonyl-CoA carboxylase deficiency (3-MCC deficiency) is an inherited condition in which the body is unable to breakdown the amino acid, leucine (a building block of protein). Some children with 3-MCC deficiency will begin developing signs and symptoms during infancy or early childhood; however, more recent studies suggest that many affected babies identified through newborn screening will never experience symptoms of the condition. 3-MCC deficiency may be associated with episodes of “metabolic crisis” in which affected people experience poor appetite, lack of energy, irritability, weakness, nausea and/or vomiting. If metabolic crises are untreated, the condition can lead to developmental delay, seizures, coma, and even death. 3-MCC deficiency is caused by changes (mutations) in MCCC1 or MCCC2 gene and is inherited in an autosomal recessive manner. Treatment may include a low-leucine diet and appropriate supplements.
For more information, visit GARD.