“…We thank Gleason and colleagues for their valuable comments. 1 The authors reported they read with great interest our findings of elevated levels of plasma glucosylsphingosine in GBA1 N370S mutation carriers, but challenged our conclusion that plasma glucosylsphingosine may serve as a useful biomarker for GBA1-related Parkinson's disease (GBA1-PD). We stand behind our statement that plasma glucosylsphingosine may serve as a useful biomarker for GBA1-PD, and acknowledge it requires clarification, especially related to specific uses of biomarkers.…”