It is usually caused by the deficiency of the enzyme cystathionine beta synthase, mutations of other related enzymes such as methionine synthase, or the deficiency of folic acid, vitamin B12 and/or pyridoxine (vitamin B6).
Homocystinuria
Hawkinsinuria
Urocanic aciduria
Alkaptonuria
Cystathioninuria
Alpha-aminoadipic and alpha-ketoadipic aciduria
Phenylketonuria
3-Methylglutaconic aciduria