Browsing by Author "Marek, Ken"

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    A proteogenomic view of Parkinson's disease causality and heterogeneity
    (Springer Nature, 2023-02-11) Kaiser, Sergio; Zhang, Luqing; Mollenhauer, Brit; Jacob, Jaison; Longerich, Simonne; Del-Aguila, Jorge; Marcus, Jacob; Raghavan, Neha; Stone, David; Fagboyegun, Olumide; Galasko, Douglas; Dakna, Mohammed; Bilican, Bilada; Dovlatyan, Mary; Kostikova, Anna; Li, Jingyao; Peterson, Brant; Rotte, Michael; Sanz, Vinicius; Foroud, Tatiana; Hutten, Samantha J.; Frasier, Mark; Iwaki, Hirotaka; Singleton, Andrew; Marek, Ken; Crawford, Karen; Elwood, Fiona; Messa, Mirko; Serrano-Fernandez, Pablo; Medical and Molecular Genetics, School of Medicine
    The pathogenesis and clinical heterogeneity of Parkinson’s disease (PD) have been evaluated from molecular, pathophysiological, and clinical perspectives. High-throughput proteomic analysis of cerebrospinal fluid (CSF) opened new opportunities for scrutinizing this heterogeneity. To date, this is the most comprehensive CSF-based proteomics profiling study in PD with 569 patients (350 idiopathic patients, 65 GBA + mutation carriers and 154 LRRK2 + mutation carriers), 534 controls, and 4135 proteins analyzed. Combining CSF aptamer-based proteomics with genetics we determined protein quantitative trait loci (pQTLs). Analyses of pQTLs together with summary statistics from the largest PD genome wide association study (GWAS) identified 68 potential causal proteins by Mendelian randomization. The top causal protein, GPNMB, was previously reported to be upregulated in the substantia nigra of PD patients. We also compared the CSF proteomes of patients and controls. Proteome differences between GBA + patients and unaffected GBA + controls suggest degeneration of dopaminergic neurons, altered dopamine metabolism and increased brain inflammation. In the LRRK2 + subcohort we found dysregulated lysosomal degradation, altered alpha-synuclein processing, and neurotransmission. Proteome differences between idiopathic patients and controls suggest increased neuroinflammation, mitochondrial dysfunction/oxidative stress, altered iron metabolism and potential neuroprotection mediated by vasoactive substances. Finally, we used proteomic data to stratify idiopathic patients into “endotypes”. The identified endotypes show differences in cognitive and motor disease progression based on previously reported protein-based risk scores.Our findings not only contribute to the identification of new therapeutic targets but also to shape personalized medicine in CNS neurodegeneration.
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    Finding useful biomarkers for Parkinson's disease
    (American Association for the Advancement of Science, 2018-08-15) Chen-Plotkin, Alice S.; Albin, Roger; Alcalay, Roy; Babcock, Debra; Bajaj, Vikram; Bowman, Dubois; Buko, Alex; Cedarbaum, Jesse; Chelsky, Daniel; Cookson, Mark; Dawson, Ted; Dewey, Richard; Foroud, Tatiana; Frasier, Mark; German, Dwight; Gwinn, Katrina; Huang, Xuemei; Kopil, Catherine; Kremer, Thomas; Lasch, Shirley; Marek, Ken; Marto, Jarrod; Merchant, Kalpana; Mollenhauer, Brit; Naito, Anna; Potashkin, Judith; Reimer, Alyssa; Rosenthal, Liana; Saunders-Pullman, Rachel; Scherzer, Clemens R.; Sherer, Todd; Singleton, Andrew; Sutherland, Margaret; Thiele, Ines; van der Brug, Marcel; Van Keuren-Jensen, Kendall; Vaillancourt, David; Walt, David; West, Andrew; Zhang, Jing; Medical and Molecular Genetics, School of Medicine
    Parkinson’s Disease affects more than 4 million people worldwide, and biomarkers to bolster the therapeutic development pipeline are urgently needed. The recent advent of an “ecosystem” of shared biosample biorepositories and data enables us to consider how to focus PD biomarker activity to best translate efforts into real-world impact.
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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.