Selective screening for lysosomal disorders in a large cohort of minority groups shows higher incidence rates and novel variants

Abstract

Fabry disease (FD) is a genetic disorder caused by defective α-galactosidase-A enzyme due to mutations in the GLA gene. A reliable diagnosis in classical FD males can be made by measuring the enzyme activity while diagnosing classical FD females and non-classical FD patients requires mutation analysis. Plasma globotriaosylsphingosine (Lyso-Gb3) has progressively gained more importance as a diagnostic biomarker for FD in recent years. Having another biomarker to complement plasma Lyso-Gb3 will increase the diagnostic accuracy in the era of mass screening, and also precision medicine. This study aims to highlight the clinical utility of the total concentration of urinary Lyso-Gb3 plus its analogues in diagnosing FD.Random urine samples collected from 42 FD patients and 48 healthy individuals. Lyso-Gb3 and its analogues were enriched by solid phase extraction and analysed by liquid chromatography tandem mass spectrometry.The total concentration of Lyso-Gb3 plus its analogues in classical FD male and female patients were 1124.4 ± 181.2 and 308.6 ± 78.6 pmol/mmol creat., respectively. The levels in non-classical FD male and female patients were 229.2 ± 169.4 and 314.4 ± 156.4 pmol/mmol creat., respectively. Urinary Lyso-Gb3 and its analogues were virtually undetectable in healthy volunteers making it 100% specific for FD diagnosis. For FD male and female patients, total concentration of urinary Lyso-Gb3 plus its analogue levels ≥0.25 pmol/mmol creat. yielded a diagnostic sensitivity and specificity of 100% (AUC = 1, p < 0.00001).Our study findings support that the total concentration of Lyso-Gb3 plus its analogues in urine is specific to FD and may provide extra diagnostic utility for both classical and non-classical FD patients.