title: Plasma lysosomal enzyme activities in congenital disorders of glycosylation, galactosemia and fructosemia.
abstract: BACKGROUND
  Variable increases in the plasma activity of different lysosomal enzymes have been reported in patients with congenital disorders of glycosylation (CDG). In particular, elevated plasma aspartylglucosaminidase activity (AGA) has been found in the majority of CDG type I patients. We report on the plasma activity of AGA and other lysosomal enzymes in patients with different types of primary and secondary CDG defects.
  
  
  METHODS
  AGA, alpha-mannosidase, beta-mannosidase and beta-hexosaminidase activities were assayed in the plasma of patients with CDGI (4CDGIa, 4CDGIx) and CDGIIx (5, all with a combined N- and O-glycosylation defect), classical galactosemia (GALT) (n=3) and hereditary fructose intolerance (HFI) (n=2).
  
  
  RESULTS
  Increased AGA and beta-hexosaminidase activities were found in all and 7/8 of the GDGI patients respectively. All enzymic activities were normal in the CDGIIx patients. Elevated AGA and beta-hexosaminidase activity was also seen in GALT and HFI patients before treatment, when transferrin isoelectric focusing (TfIEF) patterns were also abnormal.
  
  
  CONCLUSIONS
  Increased AGA plasma activity, although a consistent finding in CDGI patients, is not specific to this group of disorders since it is also observed in untreated cases of GALT and HFI. Furthermore, plasma AGA activity cannot serve as a marker for CDGII disorders. In conjunction with TfIEF it could be used in the follow up of GALT and HFI patients.
authors.affiliation: Department of Enzymology and Cellular Function, Institute of Child Health, Athens, Greece. inchildh@otenet.gr
authors.forename: Helen
authors.initials: H
authors.lastname: Michelakakis
authors.forename: Marina
authors.initials: M
authors.lastname: Moraitou
authors.forename: Irene
authors.initials: I
authors.lastname: Mavridou
authors.forename: Evangelia
authors.initials: E
authors.lastname: Dimitriou
mesh_terms: D000293:Adolescent; D001227:Aspartylglucosylaminase / Q000097:blood*; D002648:Child; D002675:Child, Preschool; D005633:Fructose Intolerance / Q000097:blood / Q000175:diagnosis / Q000201:enzymology; D015318:Fructose Metabolism, Inborn Errors / Q000097:blood / Q000175:diagnosis / Q000201:enzymology*; D005693:Galactosemias / Q000097:blood / Q000201:enzymology*; D006031:Glycosylation; D006801:Humans; D007223:Infant; D008247:Lysosomes / Q000201:enzymology; D043323:alpha-Mannosidase / Q000097:blood; D044902:beta-Mannosidase / Q000097:blood; D001619:beta-N-Acetylhexosaminidases / Q000097:blood
chemical_list: D043323:alpha-Mannosidase; D044902:beta-Mannosidase; D001619:beta-N-Acetylhexosaminidases; D001227:Aspartylglucosylaminase