Urinary total globotriaosylceramide and isoforms to identify women with Fabry disease: a diagnostic test study

Abstract

Background: Fabry disease is a treatable X-linked lysosomal storage disorder caused by alterations in the structural gene (GLA) of α-galactosidase A (AGAL), manifesting with cardiovascular and/or kidney disease and decreased life span. Although males as well as females can be affected, females cannot be identified using AGAL activity. We evaluated urinary total globotriaosylceramide (Gb3) and single N-acyl isoforms for the detection of Fabry disease in female patients with and without chronic kidney disease (CKD).

Study design: Diagnostic accuracy study.

Setting & participants: 28 untreated women with Fabry disease and 335 female outpatients without Fabry disease with (n = 213) and without CKD (n = 122).

Index test: Assessment of urinary Gb3 using electrospray ionization tandem mass spectrometry, including 6 N-acyl isoforms, total Gb3 related to urinary creatinine, and ratios of Gb3-24 to Gb3-18 and Gb3-24 to urinary AGAL.

Reference test: Fabry disease, diagnosed by identification of known pathogenic GLA mutations in patients or their male relatives.

Results: 6 parameters (ratio of Gb3-24 to urinary AGAL activity; Gb3-24; ratio of Gb3-24 to Gb3-18; Gb3-22; Gb3-16; and total Gb3) were highly informative for the diagnosis of Fabry disease independent of the presence or absence of CKD (area under the receiver operating characteristic curve, 0.876-0.927; all P < 0.001).

Limitations: Because of low signal-to-noise ratios, 15.8% of samples had to be excluded.

Conclusion: Total urinary Gb3 and Gb3 isoforms can be used for the diagnosis of Fabry disease in women.