Classification<unk>  is an organic<unk> , and because of the stereoisomeric property of<unk> -hydroxyglutarate different variants of this disorder are distinguished: L-2-hydroxyglutaric<unk>  The L-2 form is more common, severe, and mainly affects the central nervous system. The basal ganglia are affected, and cystic cavitations in the white matter of the brain are common, beginning in infancy. This form is chronic, with early symptoms such as hypotonia, tremors, and epilepsy declining into spongiform leukoencephalopathy, muscular choreodystonia, mental retardation, and psychomotor regression. It is associated with L2HGDH, which encodes L-2-hydroxyglutarate dehydrogenase. L-2-hydroxyglutarate is produced by promiscuous action of malate dehydrogenase on<unk> -oxoglutarate, and L-2-hydroxyglutarate dehydrogenase is an example of a metabolite repair enzyme that oxidizes L-2-hydroxyglutarate back to<unk> -oxoglutarate. D-2-hydroxyglutaric<unk>  The D2 form is rare, with symptoms including macrocephaly, cardiomyopathy, mental retardation, hypotonia, and cortical blindness. It is caused by recessive mutations in D2HGDH (type I) or by dominant gain-of-function mutations in IDH2 (type II). Combined D-2- and L-2-hydroxyglutaric<unk>  The combined form is characterized by severe early-onset epileptic encephalopathy and absence of developmental progress. It is caused by recessive mutations in SLC25A1 encoding the mitochondrial citrate carrier.
2-Hydroxyglutaric aciduria
3-Methylglutaconic aciduria
Aspartylglucosaminuria
Hawkinsinuria
Homocystinuria
Urocanic aciduria
Phenylketonuria
Alkaptonuria