title: Metabolomic discovery of novel urinary galabiosylceramide analogs as Fabry disease biomarkers.
abstract: Fabry disease is an X-linked, complex, multisystemic lysosomal storage disorder presenting marked phenotypic and genotypic variability among affected male and female patients. Glycosphingolipids, mainly globotriaosylceramide (Gb(3)) isoforms/analogs, globotriaosylsphingosine (lyso-Gb(3)) and analogs, as well as galabiosylceramide (Ga(2)) isoforms/analogs accumulate in the vascular endothelium, nerves, cardiomyocytes, renal glomerular and tubular epithelial cells, and biological fluids. The search for biomarkers reflecting disease severity and progression is still on-going. A metabolomic study using quadrupole time-of-flight mass spectrometry has revealed 22 galabiosylceramide isoforms/analogs in urine of untreated Fabry patients classified in seven groups according to their chemical structure: (1) Saturated fatty acid; (2) one extra double bond; (3) two extra double bonds; (4) hydroxylated saturated fatty acid; (5) hydroxylated fatty acid and one extra double bond; (6) hydrated sphingosine and hydroxylated fatty acid; (7) methylated amide linkage. Relative quantification of both Ga(2) and Gb(3) isoforms/analogs was performed. All these biomarkers are significantly more abundant in urine samples from untreated Fabry males compared with healthy male controls. A significant amount of Ga(2) isoforms/analogs, accounting for 18% of all glycosphingolipids analyzed (Ga(2) + Gb(3) and respective isoforms/analogs), were present in urine of Fabry patients. Gb(3) isoforms containing saturated fatty acids are the most abundant (60.9%) compared with 26.3% for Ga(2). A comparison between Ga(2) isoforms/analogs and their Gb(3) counterparts also showed that the proportion of analogs with hydroxylated fatty acids is significantly greater for Ga(2) (35.8%) compared with Gb(3) (1.9%). These results suggest different biological pathways involved in the synthesis and/or degradation of Gb(3) and Ga(2) metabolites.
authors.affiliation: Division of Medical Genetics, Department of Pediatrics, Faculty of Medicine and Health Sciences, Université de Sherbrooke, 3001 12th Avenue North, Quebec, J1H 5N4, Canada.
authors.forename: Michel
authors.initials: M
authors.lastname: Boutin
authors.forename: Christiane
authors.initials: C
authors.lastname: Auray-Blais
mesh_terms: D000293:Adolescent; D000328:Adult; D015415:Biomarkers / Q000652:urine*; D002648:Child; D002675:Child, Preschool; D000795:Fabry Disease / Q000652:urine*; D005732:Gangliosides / Q000652:urine*; D006801:Humans; D007223:Infant; D016018:Least-Squares Analysis; D008297:Male; D013058:Mass Spectrometry / Q000379:methods*; D055432:Metabolomics / Q000379:methods*; D008875:Middle Aged; D055815:Young Adult
chemical_list: D015415:Biomarkers; D005732:Gangliosides; C054370:galabiosylceramide