The following are the known genotypes responsible for methylmalonic acidemia:

The mut type can further be divided into mut0 and mut- subtypes, with mut0 characterized by a complete lack of methylmalonyl-CoA mutase and more severe symptoms and mut- characterized by a decreased amount of mutase activity.Mut-, cblB, and cblA versions of methylmalonic acidemia have been found to be cobalamin responsive. Mut0 is a nonresponsive variant. Treatment
Dietary
Treatment for all forms of this condition primarily relies on a low-protein diet, and depending on what variant of the disorder the individual suffers from, various dietary supplements. All variants respond to the levo isomer of carnitine as the improper breakdown of the affected substances results in sufferers developing a carnitine deficiency. The carnitine also assists in the removal of acyl-CoA, buildup of which is common in low-protein diets by converting it into acyl-carnitine which can be excreted in urine. Some forms of methylmalonyl acidemia are responsive to cobalamin although cyanocobalamin supplements could prove detrimental to some forms. If the individual proves responsive to both cobalamin and carnitine supplements, then it may be possible for them to ingest substances that include small amounts of the problematic amino acids isoleucine, threonine, methionine, and valine without causing an attack. Surgical
A more extreme treatment includes kidney or liver transplant from a donor without the condition. The foreign organs will produce a functional version of the defective enzymes and digest the methylmalonic acid, however all of the disadvantages of organ transplantation are of course applicable in this situation.
Though currently unclear if this is due to the specific mutation or early detection and treatment, despite complete nonresponse to cobalamin supplements, these individuals appeared to develop a largely benign and near completely asymptomatic version of MMA. Despite consistently showing elevated methylmalonic acid in the blood and urine, these individuals appeared for the large part developmentally normal. Notable cases
Ryan Stallings, a St. Louis infant, was mistakenly diagnosed with ethylene glycol poisoning instead of MMA in 1989, leading to a wrongful murder conviction and life sentence for his mother, Patricia Stallings. See also
Combined malonic and methylmalonic aciduria (CMAMMA)
Isovaleric acidemia
Propionic acidemia
Maple syrup urine disease

Notes
References
Further reading


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