title: Analysis of N- and O-linked protein glycosylation in children with Prader-Willi syndrome.
abstract: BACKGROUND
  Current genotype-phenotype correlations in Prader-Willi syndrome (PWS) are struggling to give an explanation of the diversity in phenotype and there is a need to move towards a molecular understanding of PWS. A range of functions related to glycoproteins are involved in the pathophysiology of PWS and it may be that abnormal glycosylation is contributing to the biological phenotype. The objective of this study was to investigate the state of N- and O-linked glycosylation in children with Prader-Willi syndrome.
  
  
  METHODS
  Twenty-three children with PWS and 20 non-PWS controls were included in the study. Protein N-linked glycosylation was assessed by analysing serum transferrin through mass spectrometry and protein O-linked through isoelectric focusing (IEF) of serum apolipoprotein C-III (apoC-III), confirmed by mass spectrometry.
  
  
  RESULTS
  The results of this analysis indicated that the N-linked glycosylation pathway in PWS is normal. A subgroup of PWS individuals was found to have a hyposialylated pattern of apoC-III isoforms. This was independent of the underlying genetic mechanism and is the first report of an apoC-III IEF abnormality in PWS.
  
  
  CONCLUSIONS
  This is the first report of apoC-III hyposialylation in PWS. As this field is in its infancy, additional study is required before these findings may be used in clinical settings.
authors.affiliation: Department of Biochemical Diseases, Mater Children's Hospital, South Brisbane, Queensland, Australia.
authors.forename: T
authors.initials: T
authors.lastname: Munce
authors.forename: H S
authors.initials: HS
authors.lastname: Heussler
authors.forename: F G
authors.initials: FG
authors.lastname: Bowling
mesh_terms: D000293:Adolescent; D053305:Apolipoprotein C-III / Q000378:metabolism; D002648:Child; D002675:Child, Preschool; D005838:Genotype; D006023:Glycoproteins / Q000378:metabolism*; D006031:Glycosylation; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007525:Isoelectric Focusing; D019158:N-Acetylneuraminic Acid / Q000378:metabolism*; D010641:Phenotype; D011218:Prader-Willi Syndrome / Q000235:genetics* / Q000378:metabolism* / Q000503:physiopathology; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D014168:Transferrin / Q000378:metabolism; D055815:Young Adult
chemical_list: D053305:Apolipoprotein C-III; D006023:Glycoproteins; D014168:Transferrin; D019158:N-Acetylneuraminic Acid