Mondo Description A form of methylmalonic acidemia with homocystinuria, an inborn error of vitamin B12 (cobalamin) metabolism characterized by variable biochemical, neurological and hematological manifestations.

Uniprot Description An autosomal recessive disorder of cobalamin metabolism characterized by decreased levels of the coenzymes adenosylcobalamin (AdoCbl) and methylcobalamin (MeCbl). Clinical features include developmental delay, hyotonia, mental retardation, seizures, megaloblastic anemia. Some patients manifest combined methylmalonic aciduria and homocystinuria (referred to as cblD original), some have only isolated homocystinuria (cblD variant 1), and others have only methylmalonic aciduria (cblD variant 2).