title: Increase in urinary purines and pyrimidines in patients with methylmalonic aciduria combined with homocystinuria.
abstract: BACKGROUND
  Methylmalonic aciduria combined with homocystinuria (MMA-HC) is the biochemical trait of a metabolic disorder resulting from impaired conversion of dietary cobalamin (cbl, or vitamin B12) to its two metabolically active forms. Effects on urinary purine and pyrimidine levels have not been described for this condition.
  
  
  METHODS
  Urine samples were collected from three patients with methylmalonic aciduria combined with homocystinuria and from 70 healthy subjects. Urinary purine and pyrimidine levels were quantitated by the use of LC/UV-Vis and LC/ESI/MS.
  
  
  RESULTS
  Higher urine levels of pyrimidines were detected with both methods in patients compared to controls.
  
  
  CONCLUSIONS
  Methylmalonic aciduria with homocystinuria is due to deficiency of the enzyme, cobalamin reductase. The enzyme defect leads to altered hepatic metabolism, which appears to modify circulating pyrimidine levels.
authors.affiliation: Department Applied Biosystems Science, University of Cagliari, Cittadella Universitaria, 09042 Monserrato (CA), Italy.
authors.forename: Simona
authors.initials: S
authors.lastname: Porcu
authors.forename: Marcella
authors.initials: M
authors.lastname: Corda
authors.forename: Franco
authors.initials: F
authors.lastname: Lilliu
authors.forename: Liliana
authors.initials: L
authors.lastname: Contini
authors.forename: Benedetta
authors.initials: B
authors.lastname: Era
authors.forename: Pietro
authors.initials: P
authors.lastname: Traldi
authors.forename: Antonella
authors.initials: A
authors.lastname: Fais
mesh_terms: D000138:Acidosis / Q000175:diagnosis / Q000652:urine; D000328:Adult; D015415:Biomarkers / Q000652:urine; D002675:Child, Preschool; D002853:Chromatography, Liquid; D006712:Homocystinuria / Q000175:diagnosis* / Q000652:urine*; D006801:Humans; D008297:Male; D008764:Methylmalonic Acid / Q000652:urine*; D008930:Mitochondria, Liver / Q000378:metabolism; D011687:Purines / Q000096:biosynthesis* / Q000652:urine*; D011743:Pyrimidines / Q000096:biosynthesis* / Q000652:urine*; D013056:Spectrophotometry, Ultraviolet
chemical_list: D015415:Biomarkers; D011687:Purines; D011743:Pyrimidines; D008764:Methylmalonic Acid