3-methylcrotonyl-CoA carboxylase (3-MCC) deficiency


3-methylcrotonyl-CoA carboxylase (3-MCC) deficiency is an inborn error of metabolism, an inherited condition in which an enzyme, 3-methylcrotonyl-CoA carboxylase, in the body is either missing or not working well. The job of this enzyme is to help break down the amino acid leucine (a part of protein). 3-MCC deficiency is an organic acid condition because it can lead to the build-up of harmful amounts of organic acids and toxins in the body. Sometimes people with 3-MCC deficiency are also found to have low levels of carnitine. Symptoms of 3-MCC deficiency can include feeding problems, vomiting, extreme tiredness/lethargy, irritability, changes in muscle tone and/or other potential signs and symptoms. Symptoms of 3-MCC deficiency can vary. Some people may not show symptoms but 3-MCC deficiency can be a potentially life-threatening condition. Illnesses or infections, going too long without food, or eating large amounts of protein are some examples of circumstances that could also trigger symptoms of 3-MCC deficiency. Management may include special precautions and emergency management recommendations, a special diet and/or medication/supplements. Support groups are available to help connect families living with 3-MCC deficiency with others who have experience or expertise with this condition.

For more information about 3-methylcrotonyl-CoA carboxylase deficiency, visit Baby's First Test: 3-methylcrotonyl-CoA carboxylase deficiency and Screening, Technology, and Research in Genetics (STAR-G): 3-methylcrotonyl-CoA carboxylase deficiency. Please see Medically Prescribed Formula for information about medically prescribed formula and pharmacologic interventions for inborn errors of metabolism. A listing of contact information for Minnesota inborn errors of metabolism medical specialty providers/clinics serving children affected with or undergoing evaluation for conditions that can be detected through Minnesota Newborn Screening is available upon request.