Methylmalonic acidaemia is caused by a deficiency of methylmalonyl CoA mutase, an enzyme on the catabolic pathway of aminoacids (isoleucine, valine, threonine and methionine) and cholesterol side chains, odd chain fatty acids and free propionate from the gut. The co-factor for the enzyme is a derivative of vitamin B12 (hydroxocobalamin). Treatment is aimed at reducing the sources of the precursors so the patients are treated with a low protein diet and medicines - carnitine and metronidazole. Some patients respond to pharmacological doses of vitamin B12.
Sections of this guideline include: background, signs of decompensation, general treatment, initial assessment and management in hospital, initial investigations, treatment, monitoring, complications, re-introduction of oral or enteral feeding.