Tandem mass spectrometry assay of β-glucocerebrosidase activity in dried blood spots eliminates false positives detected in fluorescence assay

• Published in: Molecular genetics and metabolism Vol. 123; no. 2; pp. 135 - 139
• Main Authors: Wolf, Pavlina, Alcalay, Roy N., Liong, Christopher, Cullen, Emmaline, Pauciulo, Michael W., Nichols, William C., Gan-Or, Ziv, Chung, Wendy K., Faulkner, Tina, Bentis, Christopher, Pomponio, Robert J., Ma, Xiwen, Kate Zhang, X., Keutzer, Joan M., Oliva, Petra
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.02.2018
• Subjects: Biological Assay; Biomarkers - blood; Blood Specimen Collection; Case-Control Studies; Cohort Studies; Dried Blood Spot Testing; Dried blood spots (DBS); Fluorescence; Gaucher disease (GD); Gaucher Disease - diagnosis; Gaucher Disease - metabolism; Glucocerebroside; Glucosylceramidase - blood; Humans; Lysosomal storage disorder (LSD); Mass Screening; Newborn screening (NBS); Tandem Mass Spectrometry - methods; β-Glucocerebrosidase (GBA); Dried blood spots (DBS); Glucocerebroside; Newborn screening (NBS); β-Glucocerebrosidase (GBA); Gaucher disease (GD); Lysosomal storage disorder (LSD)
• ISSN: 1096-7192; 1096-7206
• DOI: 10.1016/j.ymgme.2017.10.011

Deficiency of β-Glucocerebrosidase (GBA) activity causes Gaucher Disease (GD). GD can be diagnosed by measuring GBA activity (Beutler and Kuhl, 1990). In this study, we assayed dried blood spots from a cohort (n=528) enriched for GBA mutation carriers (n=78) and GD patients (n=18) using both the tandem mass spectrometry (MS/MS) and fluorescence assays and their respective synthetic substrates. The MS/MS assay differentiated normal controls, which included GBA mutation carriers, from GD patients with no overlap. The fluorescence assay did not always differentiate normal controls including GBA mutation carriers from GD patients and false positives were observed. The MS/MS assay improved specificity compared to the fluorescence assay. •β-Glucocerebrosidase (GBA) activity relevant to Gaucher disease (GD) can be screened by either fluorescence or mass spectrometry (MS/MS).•This study compared the two methods in the largest cohort enriched for carriers of GBA mutations or variants reported to date.•MS/MS always distinguished GD and normal samples but fluorescence yielded several false positives in samples with low normal GBA activity.•Both assays are suitable for screening GBA activity, but results in fluorescence should be followed by genotyping.