3-Methylcrotonyl-CoA carboxylase deficiency is known by many names. It is also called as 3MCC deficiency, Methylcrotonylglycinuria type 1, or BMCC. This is a disorder that can be inherited where the human body becomes incapable of properly processing some proteins. Those who suffer from this deficiency have an insufficient supply of leucine-breaking enzyme. Leucine is an amino acid which is a protein base.

3-Methylcrotonyl-CoA carboxylase deficiency is considered to be a rare illness. It was classified as rare by the Office of Rare Diseases of the NIH or the National Institutes of Health. This means that the disorder affects less than 200,000 of the US population. Worldwide, the cases are estimated at only 1 in every 50,000 individuals.

Newborn screening is now being done to determine the presence of 3-Methylcrotonyl-CoA carboxylase deficiency from the onset. It proves to be effective as more and more preventive measures are done because of the early detection of the disorder.

3-methylcrotonyl-CoA carboxylase is an enzyme which is comprised of the MCCC1 and the MCCC2 genes. These two genes create sub-units of protein to create the necessary enzyme that breaks down Leucine. The specific step wherein the enzyme plays a part is the fourth step of leucine breakdown. Once any of the two genes mutate, a reduction or elimination of the 3-methylcrotonyl-CoA carboxylase activity results and very soon, the body fails to process leucine. When the levels of leucine buildup reach a harmful level, the toxins would begin to damage the nervous system.

Infants and children are the primary victims of this deficiency. The sad thing is, most infants appear normal after being born and the symptoms only begin to show during the child’s first year of life. The characteristic traits of this disorder include feeding complexities, lethargy or the feeling of extreme tiredness, hypotonia (a condition where the muscle tones become weak), diarrhea, vomiting, seizures, and in the worst of cases, even coma or death. These complications can be prevented once the disorder is detected early on and then managed. A good method of management is the administration of supplements and a diet that is low in protein. Some cases do not develop any signs or symptoms and this is true when the patients undergo gene mutations. Reye syndrome is a similar illness wherein the children appear to be recuperating from an influenza or chicken pox.

3methylcrotonylcoacarboxylasedeficiency