An inherited organic acid disorder where an enzyme deficiency impairs the body's ability to break down certain proteins (methionine, threonine, isoleucine and valine) consumed in the diet. This results in a buildup of glycine and methylmalonic acid which results in harmful affects. The disorder results from a combined synthesis defect of AdoCbl and MeCbl. See also Methylmalonic acidemia, synthesis defect of AdoCbl and MeCbl
