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ABSTRACT: The aim of this study was to determine whether globotriaosylceramide (Gb3) is a useful biomarker in Fabry disease.
The levels of Gb3 were measured in plasma and urine by tandem mass spectrometry in untreated hemizygotes and heterozygotes with Fabry disease and in healthy controls, and the levels were monitored in patients on treatment with enzyme replacement therapy (ERT).
Hemizygotes with classic Fabry disease showed elevated levels of Gb3 in both plasma and urine and could readily be distinguished from normal controls. Male patients with the N215S mutation had normal levels in their plasma but 50% had marginally elevated levels in their urine. Thirty-three percent of proven heterozygotes had elevated Gb3 concentrations in plasma but 97% of those without the N215S mutation (36/37) had an elevated level in urine. The four heterozygotes with the N215S mutation had normal Gb3 levels in urine. The level of Gb3 in plasma initially fell following the start of ERT in all patients who had an elevated level before treatment. However, in a few patients the level subsequently rose. Similar results were found for the levels of Gb3 in urine.
Gb3 is not an ideal marker of Fabry disease or the response to treatment in all patients. Plasma and urine levels of Gb3 cannot be used as a marker of Fabry disease in patients with the N215S mutation and many heterozygotes do not have elevated Gb3 levels in plasma. The urine concentration is more informative in heterozygotes and can be used as a measure of the response to therapy. The fall in Gb3 levels in patients receiving ERT was not sustained in some patients, despite a clinical improvement. Additionally, Gb3 cannot be used to monitor the response to treatment in patients who initially have normal plasma and urine concentrations of this glycolipid.
Acta paediatrica (Oslo, Norway: 1992). Supplement 04/2005; 94(447):51-4; discussion 37-8.
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ABSTRACT: Elevated plasma aspartylglucosaminidase activity was found in 21/25 cases of CDG Ia, in single cases of CDG Ib, Ic and If, and in 15/16 cases of CDG Ix. The CDG I patients in whom the activity was not raised were either atypical clinically (CDG Ia) or very young (CDG Ih).
Journal of Inherited Metabolic Disease 02/2005; 28(6):1197-8. · 3.58 Impact Factor
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ABSTRACT: Fabry disease is an X-linked disorder of glycosphingolipid metabolism resulting from a deficiency of the lysosomal enzyme alpha-galactosidase A. This deficiency leads to the progressive accumulation, in lysosomes of visceral tissues and in body fluids of hemizygotes, of the glycosphingolipids globotriaosylceramide (CTH, Gb(3) or GL-3) and galabiosylceramide (CDH) and to a lesser extent the blood group AB and B related glycolipids. Elevated levels of the glycosphingolipids are found in the urine of hemizygous males with the classic phenotype, but it is not known whether all symptomatic or asymptomatic heterozygotes have elevated levels. We have therefore measured CTH and CDH quantitatively in a multiplex assay using tandem mass spectrometry in urine from a large cohort (44) of genetically proven or obligate heterozygotes including four with the N215S mutation, from classic hemizygotes (28), from cardiac variant hemizygotes with the N215S mutation (6) and from normal controls. The levels of CTH and CDH were related to both creatinine and sphingomyelin. Urinary CTH was elevated in all 28 classic hemizygotes but only in 4/6 of the cardiac variants. The level was within or just above the normal reference range in the four individuals heterozygous for the N215S mutation but was elevated in 38/40 of the other heterozygotes. Similar results were obtained for CDH, except that only 34/40 heterozygotes had an elevated level. The level of CDH was not elevated in the four heterozygotes and 4/6 of the hemizygotes for the N215S mutation. Combining the levels of CTH and CDH did not improve the discrimination of heterozygotes from controls. The ratio of CDH to CTH was higher in heterozygotes than in hemizygotes. Measurement of urinary CTH gave the best discrimination of heterozygotes from controls.
Journal of Inherited Metabolic Disease 02/2005; 28(1):35-48. · 3.58 Impact Factor
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ABSTRACT: The N-linked glycans on transferrin and alpha(1)-antitrypsin from patients with congenital disorders of glycosylation type I have increased fucosylation and branching relative to normal controls. The elevated levels of monofucosylated biantennary glycans are probably due to increased alpha-(1-->6) fucosylation. The presence of bi- and trifucosylated triantennary and tetra-antennary glycans indicated that peripheral alpha-(1-->3), as well as core alpha-(1-->6), fucosylation is increased. Altered processing was observed on both the fully and underglycosylated glycoforms.
Biochemical Journal 10/2001; 359(Pt 2):249-54. · 4.90 Impact Factor