Classification of Amino Acid and Organic Acid Metabolic Disorders 

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Aspartate related*

• Canavan's disease (aspartoacylase deficiency)

Lysine related

• Hyperlysinemia (lysine-ketoglutarate reductase deficiency more severe than saccharopine dehydrogenase deficiency)

• Saccharopinuria (lysine-ketoglutarate reductase deficiency less severe than saccharopine dehydrogenase deficiency)

• Glutaric acidemic, type I (mitochondrial flavin adenine dinucleotide dependent glutaryl-CoA dehydrogenase deficiency)

• Glutaric acidemic, type II (? multiple acyl-CoA dehydrogenases deficiency)

• Hyperpipecolic acidemia (mechanism not known)

Phenylalanine related (hyperphenylalaninaemia, HPA)

• HPA type I: classic phenylketonuria (phenylalanine hydroxylase deficiency)

• HPA type II: atypical PKU

• HPA type III: non-PKU HPA (mild HPA)

Tyrosine related

• Tyrosinaemia type I

Branched-chain amino acids (valine, leucine, and isoleucine) related

• Maple syrup urine disease

• Methylmalonic aciduria

• Propionic aciduria

• Isovaleric aciduria

• Others

Lysine and tryptophan related

• Glutaric aciduria type I

Tryptophan related

• Possibly Unverricht-Lundborg disease (to be proved)

Sulfur containing amino acid related

• Homocystinuria (cystathionine Beta-synthase deficiency)

• Hypermethioninemia

• Combined homocystinuria and methylmalonic aciduria (5-methyltetrahydrofolate reductase deficiency)

• Sulfate oxidase deficiency

Defective transport

• Hartnup disease (neutral and aromatic amino acid)

Entities with metabolic pathways poorly understood

• L-2-hydroxyglutaric aciduria

NeuroLearn NeuroHelp Metabolic  For Comment: KarMing-Fung@ouhsc.edu