Multiplex Tandem Mass Spectrometry Analysis of Novel Plasma Lyso-Gb3-Related Analogues in Fabry Disease

Fabry disease is a multisystemic, X-linked lysosomal storage disorder caused by a deficit in alpha-galactosidase A enzyme activity leading to glycosphingolipid accumulation, mainly globo-triaosylceramide (Gb(3)) and globotriaosylsphingosine (lyso-Gb(3)). Recent metabolomic studies have led to the discovery of novel biomarkers related to lyso-Gb(3) in plasma and urine. These biomarkers show modifications of the sphingosine moiety of the lyso-Gb(3) molecule. The objectives of this study were to develop and validate a liquid chromatography-tandem mass spectrometry method for the relative quantification of novel plasma lyso-Gb(3)-related analogues, to evaluate their levels in plasma of 74 Fabry patients and 41 healthy controls and to correlate these results with patient gender, enzyme replacement therapy treatment, and lyso-Gb(3) analogue levels previously measured in urine for the same patients. As expected, the concentrations of lyso-Gb(3) and its related analogues in plasma are higher in Fabry males compared to Fabry females and higher for untreated males compared to treated males. The concentration of lyso-Gb(3) and its related analogues in plasma decrease significantly after the beginning of enzyme replacement therapy (ERT) treatment and remain stable for 30 months of monitored therapy in a Fabry male. In plasma, lyso-Gb(3) is significantly more abundant than its related analogues, which differs from urine where the majority of the lyso-Gb(3) analogues are more increased than lyso-Gb(3) itself. In contrast to urine, the relative distribution of lyso-Gb(3) and its analogues in plasma is similar from one individual to another in the same group of Fabry patients, irrespective of ERT. This study revealed a large discrepancy between the relative abundance of lyso-Gb(3) and its analogues in urine and plasma. Further studies will thus be needed to better understand the metabolic relationship between plasma and urine lyso-Gb(3)-related biomarkers.