title: Markers associated with inborn errors of metabolism of branched-chain amino acids and their relevance to upper levels of intake in healthy people: an implication from clinical and molecular investigations on maple syrup urine disease.
abstract: Maple syrup urine disease (MSUD) is caused by a deficiency in the branched-chain alpha-ketoacid dehydrogenase complex. Accumulations of branched-chain amino acids (BCAAs) and branched-chain alpha-ketoacids (BCKAs) in patients with MSUD induce ketoacidosis, neurological disorders, and developmental disturbance. BCAAs and BCKAs influence on the nervous system can be estimated by analyzing these patients. According to clinical investigations on MSUD patients, leucine levels over 400 micromol/L apparently can cause any clinical problem derived from impaired function of the central nervous system. Damage to neuronal cells found in MSUD patients are presumably because of higher concentrations of both blood BCAAs or BCKAs, especially alpha-ketoisocapronic acids. These clinical data from MSUD patients provide a valuable basis on understanding leucine toxicity in the normal subject.
authors.affiliation: Department of Pediatrics, Graduate School of Medical Sciences, Kumamoto University, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Mitsubuchi
authors.forename: Misao
authors.initials: M
authors.lastname: Owada
authors.forename: Fumio
authors.initials: F
authors.lastname: Endo
mesh_terms: D042942:3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide) / Q000378:metabolism* / Q000652:urine; D000597:Amino Acids, Branched-Chain / Q000009:adverse effects / Q000378:metabolism* / Q000502:physiology; D015415:Biomarkers; D004032:Diet; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007930:Leucine / Q000009:adverse effects* / Q000097:blood; D016031:Liver Transplantation; D008375:Maple Syrup Urine Disease / Q000235:genetics / Q000378:metabolism / Q000628:therapy
chemical_list: D000597:Amino Acids, Branched-Chain; D015415:Biomarkers; D042942:3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide); D007930:Leucine