methylcobalamin deficiency type G

methylcobalamin deficiency type G

An autosomal recessive condition (OMIM:250940) characterised by mental retardation, macrocytic anaemia, homocystinuria and mild hyperhomocysteinaemia, as well as a slightly increased risk of cardiovascular disease and neural tube defects.
Molecular pathology
Defects in MTR, which encodes an enzyme that transfers a methyl group from methyl-cobalamin to homocysteine, cause methylcobalamin deficiency type G.