Browsing by Author "Simuni, Tatyana"

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    Genetic Testing for Parkinson Disease: Are We Ready?
    (American Academy of Neurology, 2021-02) Cook, Lola; Schulze, Jeanine; Kopil, Catherine; Hastings, Tara; Naito, Anna; Wojcieszek, Joanne; Payne, Katelyn; Alcalay, Roy N.; Klein, Christine; Saunders-Pullman, Rachel; Simuni, Tatyana; Foroud, Tatiana; Medical and Molecular Genetics, School of Medicine
    Purpose of review: With the advent of precision medicine and demand for genomic testing information, we may question whether it is time to offer genetic testing to our patients with Parkinson disease (PD). This review updates the current genetic landscape of PD, describes what genetic testing may offer, provides strategies for evaluating whom to test, and provides resources for the busy clinician. Recent findings: Patients with PD and their relatives, in various settings, have expressed an interest in learning their PD genetic status; however, physicians may be hesitant to widely offer testing due to the perceived low clinical utility of PD genetic test results. The rise of clinical trials available for patients with gene-specific PD and emerging information on genotype-phenotype correlations are starting to shift this discussion about testing. Summary: By learning more about the various genetic testing options for PD and utility of results for patients and their care, clinicians may become more comfortable with widespread PD genetic testing in the research and clinical setting.
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    International Genetic Testing and Counseling Practices for Parkinson's Disease
    (Wiley, 2023) Saunders-Pullman, Rachel; Raymond, Deborah; Ortega, Roberto A.; Shalash, Ali; Gatto, Emilia; Salari, Mehri; Markgraf, Maggie; Alcalay, Roy N.; Mascalzoni, Deborah; Mencacci, Niccolò E.; Bonifati, Vincenzo; Merello, Marcelo; Chung, Sun Ju; Novakovic, Ivana; Bardien, Soraya; Pal, Gian; Hall, Anne; Hattori, Nobutaka; Lynch, Timothy; Thaler, Avner; Sue, Carolyn M.; Foroud, Tatiana; Verbrugge, Jennifer; Schulze, Jeanine; Cook, Lola; Marder, Karen; Suchowersky, Oksana; Klein, Christine; Simuni, Tatyana; Medical and Molecular Genetics, School of Medicine
    Background: There is growing clinical and research utilization of genetic testing in Parkinson's disease (PD), including direct-to-consumer testing. Objectives: The aim is to determine the international landscape of genetic testing in PD to inform future worldwide recommendations. Methods: A web-based survey assessing current practices, concerns, and barriers to genetic testing and counseling was administered to the International Parkinson and Movement Disorders Society membership. Results: Common hurdles across sites included cost and access to genetic testing, and counseling, as well as education on genetic counseling. Region-dependent differences in access to and availability of testing and counseling were most notable in Africa. High-income countries also demonstrated heterogeneity, with European nations more likely to have genetic testing covered through insurance than Pan-American and Asian countries. Conclusions: This survey highlights not only diversity of barriers in different regions but also the shared and highly actionable needs for improved education and access to genetic counseling and testing for PD worldwide. © 2023 International Parkinson and Movement Disorder Society.
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    LRRK2-associated parkinsonism with and without in vivo evidence of alpha-synuclein aggregates: longitudinal clinical and biomarker characterization
    (Oxford University Press, 2025-03-06) Chahine, Lana M.; Lafontant, David-Erick; Choi, Seung Ho; Iwaki, Hirotaka; Blauwendraat, Cornelis; Singleton, Andrew B.; Brumm, Michael C.; Alcalay, Roy N.; Merchant, Kalpana; Holohan Nudelman, Kelly Nicole; Dagher, Alain; Vo, Andrew; Tao, Qin; Venuto, Charles S.; Kieburtz, Karl; Poston, Kathleen L.; Bressman, Susan; Gonzalez-Latapi, Paulina; Avants, Brian; Coffey, Christopher; Jennings, Danna; Tolosa, Eduardo; Siderowf, Andrew; Marek, Ken; Simuni, Tatyana; Parkinson’s Progression Markers Initiative; Medical and Molecular Genetics, School of Medicine
    Among LRRK2-associated parkinsonism cases with nigral degeneration, over two-thirds demonstrate evidence of pathologic alpha-synuclein, but many do not. Understanding the clinical phenotype and underlying biology in such individuals is critical for therapeutic development. Our objective was to compare clinical and biomarker features, and rate of progression over 4 years of follow-up, among LRRK2-associated parkinsonism cases with and without in vivo evidence of alpha-synuclein aggregates. Data were from the Parkinson's Progression Markers Initiative, a multicentre prospective cohort study. The sample included individuals diagnosed with Parkinson disease with pathogenic variants in LRRK2. Presence of CSF alpha-synuclein aggregation was assessed with seed amplification assay. A range of clinician- and patient-reported outcome assessments were administered. Biomarkers included dopamine transporter scan, CSF amyloid-beta1-42, total tau, phospho-tau181, urine bis(monoacylglycerol)phosphate levels and serum neurofilament light chain. Linear mixed-effects (LMMs) models examined differences in trajectory in CSF-negative and CSF-positive groups. A total of 148 LRRK2 parkinsonism cases (86% with G2019S variant), 46 negative and 102 positive for CSF alpha-synuclein seed amplification assay, were included. At baseline, the negative group was older than the positive group [median (inter-quartile range) 69.1 (65.2-72.3) versus 61.5 (55.6-66.9) years, P < 0.001] and a greater proportion were female [28 (61%) versus 43 (42%), P = 0.035]. Despite being older, the negative group had similar duration since diagnosis and similar motor rating scale [16 (11-23) versus 16 (10-22), P = 0.480] though lower levodopa equivalents. Only 13 (29%) of the negative group were hyposmic, compared with 75 (77%) of the positive group. The negative group, compared with the positive group, had higher per cent-expected putamenal dopamine transporter binding for their age and sex [0.36 (0.29-0.45) versus 0.26 (0.22-0.37), P < 0.001]. Serum neurofilament light chain was higher in the negative group compared with the positive group [17.10 (13.60-22.10) versus 10.50 (8.43-14.70) pg/mL; age-adjusted P-value = 0.013]. In terms of longitudinal change, the negative group remained stable in functional rating scale score in contrast to the positive group who had a significant increase (worsening) of 0.729 per year (P = 0.037), but no other differences in trajectory were found. Among individuals diagnosed with Parkinson disease with pathogenic variants in the LRRK2 gene, we found clinical and biomarker differences in cases without versus with in vivo evidence of CSF alpha-synuclein aggregates. LRRK2 parkinsonism cases without evidence of alpha-synuclein aggregates as a group exhibit less severe motor manifestations and decline. The underlying biology in LRRK2 parkinsonism cases without evidence of alpha-synuclein aggregates requires further investigation.