The MMACHC gene is located on 1p34.1 chromosome. The protein encoded by this gene comprises 282 amino acids, and weighs approximately 32 kDa. The exact function of this protein is not known. It may play a role in the binding and intracellular trafficking of cobalamin (vitamin B12).
Defects in this protein are responsible for methylmalonic aciduria and homocystinuria type cblC disorder, characterized by decreased levels of the coenzymes adenosylcobalamin (AdoCbl) and methylcobalamin (MeCbl). Affected patients may have developmental, hematologic, neurologic, metabolic, ophthalmologic, and dermatologic clinical findings.