Browsing by Subject "Psychosine"

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    Glucosylsphingosine (Lyso-Gb1): An Informative Biomarker in the Clinical Monitoring of Patients with Gaucher Disease.
    (International journal of molecular sciences, 2022-11) Gayed, Matthew M; Jung, Seung-Hye; Huggins, Erin; Rodriguez-Rassi, Eleanor; DeArmey, Stephanie; Kishnani, Priya Sunil; Stiles, Ashlee R
    Historically, disease burden and treatment responses in patients with Gaucher disease (GD) was assessed by monitoring clinical data, laboratory, imaging, chitotriosidase (CHITO), and other biomarkers; however, these biomarkers lack specificity and CHITO is uninformative in patients heterozygous or homozygous for the CHIT1 c.1049_1072dup24 variant. Recently, glucosylsphingosine (lyso-Gb1), a sensitive and specific GD biomarker, has been recommended for patient monitoring. Furthermore, studies measuring lyso-Gb1 and CHITO in patients on long-term treatment with enzyme replacement therapy (ERT) and/or substrate reduction therapy (SRT) reported as group data show a reduction in both analytes, yet individualized patient data are generally unavailable. We describe seven patients on long-term treatment with longitudinal clinical data with monitoring based on current treatment guidelines. We present four patients who exhibit stable disease with normalized CHITO despite elevated lyso-Gb1. We present one patient who transitioned from ERT to SRT due to lack of a clinical response with life-threatening thrombocytopenia who responded with marked improvement in platelets, and normalized levels of both CHITO and lyso-Gb1. Finally, we present two ERT to SRT switch patients with stable disease on ERT who exhibited non-compliance on SRT, one with mirrored marked elevations of CHITO and lyso-Gb1; and another with normal CHITO and platelets, but increasing lyso-Gb1 levels and enlarged spleen. These clinical vignettes highlight the role of lyso-Gb1 as a sensitive biomarker in management of patients with GD, and its further value when CHITO is normal and thus uninformative. We highlight the personalized medicine approach needed to optimize treatment outcomes and recommendations for these patients.
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    The critical role of psychosine in screening, diagnosis, and monitoring of Krabbe disease.
    (Genetics in medicine : official journal of the American College of Medical Genetics, 2020-06) Guenzel, Adam J; Turgeon, Coleman T; Nickander, Kim K; White, Amy L; Peck, Dawn S; Pino, Gisele B; Studinski, April L; Prasad, Vinod K; Kurtzberg, Joanne; Escolar, Maria L; Lasio, Maria Laura Duque; Pellegrino, Joan E; Sakonju, Ai; Hickey, Rachel E; Shallow, Natalie M; Ream, Margie A; Orsini, Joseph J; Gelb, Michael H; Raymond, Kimiyo; Gavrilov, Dimitar K; Oglesbee, Devin; Rinaldo, Piero; Tortorelli, Silvia; Matern, Dietrich

    Purpose

    Newborn screening (NBS) for Krabbe disease (KD) is performed by measurement of galactocerebrosidase (GALC) activity as the primary test. This revealed that GALC activity has poor specificity for KD. Psychosine (PSY) was proposed as a disease marker useful to reduce the false positive rate for NBS and for disease monitoring. We report a highly sensitive PSY assay that allows identification of KD patients with minimal PSY elevations.

    Methods

    PSY was extracted from dried blood spots or erythrocytes with methanol containing d5-PSY as internal standard, and measured by liquid chromatography-tandem mass spectrometry.

    Results

    Analysis of PSY in samples from controls (N = 209), GALC pseudodeficiency carriers (N = 55), GALC pathogenic variant carriers (N = 27), patients with infantile KD (N = 26), and patients with late-onset KD (N = 11) allowed for the development of an effective laboratory screening and diagnostic algorithm. Additional longitudinal measurements were used to track therapeutic efficacy of hematopoietic stem cell transplantion (HSCT).

    Conclusion

    This study supports PSY quantitation as a critical component of NBS for KD. It helps to differentiate infantile from later onset KD variants, as well as from GALC variant and pseudodeficiency carriers. Additionally, this study provides further data that PSY measurement can be useful to monitor KD progression before and after treatment.