Browsing by Author "Simon, David K."

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    Differences in the Presentation and Progression of Parkinson's Disease by Sex
    (Wiley, 2021) Iwaki, Hirotaka; Blauwendraat, Cornelis; Leonard, Hampton L.; Makarious, Mary B.; Kim, Jonggeol J.; Liu, Ganqiang; Maple-Grødem, Jodie; Corvol, Jean-Christophe; Pihlstrøm, Lasse; van Nimwegen, Marlies; Smolensky, Luba; Amondikar, Ninad; Hutten, Samantha J.; Frasier, Mark; Nguyen, Khanh-Dung H.; Rick, Jacqueline; Eberly, Shirley; Faghri, Faraz; Auinger, Peggy; Scott, Kirsten M.; Wijeyekoon, Ruwani; Van Deerlin, Vivianna M.; Hernandez, Dena G.; Gibbs, Raphael J.; Day-Williams, Aaron G.; Brice, Alexis; Alves, Guido; Noyce, Alastair J.; Tysnes, Ole-Bjørn; Evans, Jonathan R.; Breen, David P.; Estrada, Karol; Wegel, Claire E.; Danjou, Fabrice; Simon, David K.; Andreassen, Ole A.; Ravina, Bernard; Toft, Mathias; Heutink, Peter; Bloem, Bastiaan R.; Weintraub, Daniel; Barker, Roger A.; Williams-Gray, Caroline H.; van de Warrenburg, Bart P.; Van Hilten, Jacobus J.; Scherzer, Clemens R.; Singleton, Andrew B.; Nalls, Mike A.; Medical and Molecular Genetics, School of Medicine
    Background: Previous studies reported various symptoms of Parkinson's disease (PD) associated with sex. Some were conflicting or confirmed in only one study. Objectives: We examined sex associations to PD phenotypes cross-sectionally and longitudinally in large-scale data. Methods: We tested 40 clinical phenotypes, using longitudinal, clinic-based patient cohorts, consisting of 5946 patients, with a median follow-up of 3.1 years. For continuous outcomes, we used linear regressions at baseline to test sex-associated differences in presentation, and linear mixed-effects models to test sex-associated differences in progression. For binomial outcomes, we used logistic regression models at baseline and Cox regression models for survival analyses. We adjusted for age, disease duration, and medication use. In the secondary analyses, data from 17 719 PD patients and 7588 non-PD participants from an online-only, self-assessment PD cohort were cross-sectionally evaluated to determine whether the sex-associated differences identified in the primary analyses were consistent and unique to PD. Results: Female PD patients had a higher risk of developing dyskinesia early during the follow-up period, with a slower progression in activities of daily living difficulties, and a lower risk of developing cognitive impairments compared with male patients. The findings in the longitudinal, clinic-based cohorts were mostly consistent with the results of the online-only cohort. Conclusions: We observed sex-associated contributions to PD heterogeneity. These results highlight the necessity of future research to determine the underlying mechanisms and importance of personalized clinical management.
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    Maternal inheritance and mitochondrial DNA variants in familial Parkinson's disease
    (BMC, 2010-04-01) Simon, David K.; Pankratz, Nathan; Kissell, Diane K.; Pauciulo, Michael W.; Halter, Cheryl A.; Rudolph, Alice; Pfeiffer, Ronald F.; Nichols, William C.; Foroud, Tatiana; Parkinson Study Group - PROGENI Investigators; Medical and Molecular Genetics, School of Medicine
    Background Mitochondrial function is impaired in Parkinson's disease (PD) and may contribute to the pathogenesis of PD, but the causes of mitochondrial impairment in PD are unknown. Mitochondrial dysfunction is recapitulated in cell lines expressing mitochondrial DNA (mtDNA) from PD patients, implicating mtDNA variants or mutations, though the role of mtDNA variants or mutations in PD risk remains unclear. We investigated the potential contribution of mtDNA variants or mutations to the risk of PD. Methods We examined the possibility of a maternal inheritance bias as well as the association between mitochondrial haplogroups and maternal inheritance and disease risk in a case-control study of 168 multiplex PD families in which the proband and one parent were diagnosed with PD. 2-tailed Fisher Exact Tests and McNemar's tests were used to compare allele frequencies, and a t-test to compare ages of onset. Results The frequency of affected mothers of the proband with PD (83/167, 49.4%) was not significantly different from the frequency of affected females of the proband generation (115/259, 44.4%) (Odds Ratio 1.22; 95%CI 0.83 - 1.81). After correcting for multiple tests, there were no significant differences in the frequencies of mitochondrial haplogroups or of the 10398G complex I gene polymorphism in PD patients compared to controls, and no significant associations with age of onset of PD. Mitochondrial haplogroup and 10398G polymorphism frequencies were similar in probands having an affected father as compared to probands having an affected mother. Conclusions These data fail to demonstrate a bias towards maternal inheritance in familial PD. Consistent with this, we find no association of common haplogroup-defining mtDNA variants or for the 10398G variant with the risk of PD. However, these data do not exclude a role for mtDNA variants in other populations, and it remains possible that other inherited mitochondrial DNA variants, or somatic mDNA mutations, contribute to the risk of familial PD.
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    Meta-analysis of Parkinson disease: Identification of a novel locus, RIT2
    (Wiley, 2012) Pankratz, Nathan; Beecham, Gary W.; DeStefano, Anita L.; Dawson, Ted M.; Doheny, Kimberly F.; Factor, Stewart A.; Hamza, Taye H.; Hung, Albert Y.; Hyman, Bradley T.; Ivinson, Adrian J.; Krainc, Dmitri; Latourelle, Jeanne C.; Clark, Lorraine N.; Marder, Karen; Martin, Eden R.; Mayeux, Richard; Ross, Owen A.; Scherzer, Clemens R.; Simon, David K.; Tanner, Caroline; Vance, Jeffery M.; Wszolek, Zbigniew K.; Zabetian, Cyrus P.; Myers, Richard H.; Payami, Haydeh; Scott, William K.; Foroud, Tatiana; PD GWAS Consortium; Medical and Molecular Genetics, School of Medicine
    Objective: Genome-wide association (GWAS) methods have identified genes contributing to Parkinson's disease (PD); we sought to identify additional genes associated with PD susceptibility. Methods: A 2-stage design was used. First, individual level genotypic data from 5 recent PD GWAS (Discovery Sample: 4,238 PD cases and 4,239 controls) were combined. Following imputation, a logistic regression model was employed in each dataset to test for association with PD susceptibility and results from each dataset were meta-analyzed. Second, 768 single-nucleotide polymorphisms (SNPs) were genotyped in an independent Replication Sample (3,738 cases and 2,111 controls). Results: Genome-wide significance was reached for SNPs in SNCA (rs356165; G: odds ratio [OR]=1.37; p=9.3×10(-21)), MAPT (rs242559; C: OR=0.78; p=1.5×10(-10)), GAK/DGKQ (rs11248051; T: OR=1.35; p=8.2×10(-9)/rs11248060; T: OR=1.35; p=2.0×10(-9)), and the human leukocyte antigen (HLA) region (rs3129882; A: OR=0.83; p=1.2×10(-8)), which were previously reported. The Replication Sample confirmed the associations with SNCA, MAPT, and the HLA region and also with GBA (E326K; OR=1.71; p=5×10(-8) Combined Sample) (N370; OR=3.08; p=7×10(-5) Replication sample). A novel PD susceptibility locus, RIT2, on chromosome 18 (rs12456492; p=5×10(-5) Discovery Sample; p=1.52×10(-7) Replication sample; p=2×10(-10) Combined Sample) was replicated. Conditional analyses within each of the replicated regions identified distinct SNP associations within GBA and SNCA, suggesting that there may be multiple risk alleles within these genes. Interpretation: We identified a novel PD susceptibility locus, RIT2, replicated several previously identified loci, and identified more than 1 risk allele within SNCA and GBA.