What are the types of homocystinuria?

Homocystinuria type-I-

Due to the deficiency of cystathionine ß synthase, Most common inborn error of methionine metabolism.

homocystinuria type-II –

Homocystinuria due to defect in methylcobalamin formation, Characterized by the triad of megaloblastic anemia, Homocystinuria and hypomethionemia.

Homocystinuria type-III-

Deficiency of the enzyme methyltetrahydrofolate reductase, Characterized by homocystinemia,homocystinuria, Low-low normal levels of methionine