Genome-wide Association and Meta-analysis of Age-at-Onset in Parkinson Disease: Evidence From COURAGE-PD Consortium 10.1212/WNL.0000000000200699

in Neurology (2022)

Background and Objectives: Considerable heterogeneity exists in the literature concerning genetic determinants of the age of onset (AAO) of Parkinson\textquoterights disease (PD), which could be ... [more ▼]

Background and Objectives: Considerable heterogeneity exists in the literature concerning genetic determinants of the age of onset (AAO) of Parkinson\textquoterights disease (PD), which could be attributed to lack of well-powered replication cohorts. The previous largest GWAS identified SNCA and TMEM175 loci on chromosome (Chr) 4 with a significant influence on AAO of PD, these have not been independently replicated. The present study aims to conduct a meta-analysis of GWAS of PD AAO and validate previously observed findings in worldwide populations.Methods: A meta-analysis was performed on PD AAO GWAS of 30 populations of predominantly European ancestry from the Comprehensive Unbiased Risk Factor Assessment for Genetics and Environment in Parkinson\textquoterights Disease (COURAGE-PD) consortium. This was followed up by combining our study with the largest publicly available European ancestry dataset compiled by the International Parkinson disease Genomics Consortium (IPDGC).Results: The COURAGE-PD included a cohort of 8,535 patients with PD (91.9\%: Europeans, 9.1\%: East-Asians). The average AAO in the COURAGE-PD dataset was 58.9 years (SD=11.6), with an under-representation of females (40.2\%). The heritability estimate for AAO in COURAGE-PD was 0.083 (SE=0.057). None of the loci reached genome-wide significance (P\<5x10-8). Nevertheless, the COURAGE-PD dataset confirmed the role of the previously published TMEM175 variant as genetic determinant of AAO of PD with Bonferroni-corrected nominal levels of significance (P\<0.025): (rs34311866:β(SE)COURAGE=0.477(0.203), PCOURAGE=0.0185). The subsequent meta-analysis of COURAGE-PD and IPDGC datasets (Ntotal=25,950) led to the identification of two genome-wide significant association signals on Chr 4, including the previously reported SNCA locus (rs983361:β(SE)COURAGE+IPDGC=0.720(0.122), PCOURAGE+IPDGC=3.13x10-9) and a novel BST1 locus (rs4698412:β(SE)COURAGE+IPDGC=-0.526(0.096), PCOURAGE+IPDGC=4.41x10-8).Discussion: Our study further refines the genetic architecture of Chr 4 underlying the AAO of the PD phenotype through the identification of BST1 as a novel AAO PD locus. These findings open a new direction for the development of treatments to delay the onset of PD. [less ▲]

Mendelian randomization study of smoking, alcohol, and coffee drinking in relation to Parkinso's disease

in Journal of Parkinson's Disease (2021)

Background:Previous studies showed that lifestyle behaviors (cigarette smoking, alcohol, coffee) are inversely associated with Parkinson’s disease (PD). The prodromal phase of PD raises the possibility ... [more ▼]

Background:Previous studies showed that lifestyle behaviors (cigarette smoking, alcohol, coffee) are inversely associated with Parkinson’s disease (PD). The prodromal phase of PD raises the possibility that these associations may be explained by reverse causation. Objective:To examine associations of lifestyle behaviors with PD using two-sample Mendelian randomisation (MR) and the potential for survival and incidence-prevalence biases. Methods:We used summary statistics from publicly available studies to estimate the association of genetic polymorphisms with lifestyle behaviors, and from Courage-PD (7,369 cases, 7,018 controls; European ancestry) to estimate the association of these variants with PD. We used the inverse-variance weighted method to compute odds ratios (ORIVW) of PD and 95%confidence intervals (CI). Significance was determined using a Bonferroni-corrected significance threshold (p = 0.017). Results:We found a significant inverse association between smoking initiation and PD (ORIVW per 1-SD increase in the prevalence of ever smoking = 0.74, 95%CI = 0.60–0.93, p = 0.009) without significant directional pleiotropy. Associations in participants ≤67 years old and cases with disease duration ≤7 years were of a similar size. No significant associations were observed for alcohol and coffee drinking. In reverse MR, genetic liability toward PD was not associated with smoking or coffee drinking but was positively associated with alcohol drinking. Conclusion:Our findings are in favor of an inverse association between smoking and PD that is not explained by reverse causation, confounding, and survival or incidence-prevalence biases. Genetic liability toward PD was positively associated with alcohol drinking. Conclusions on the association of alcohol and coffee drinking with PD are hampered by insufficient statistical power. [less ▲]

Dopamine oxidation mediates mitochondrial and lysosomal dysfunction in Parkinson's disease.

in Science (2017), 357(6357), 1255-1261

Mitochondrial and lysosomal dysfunction have been implicated in substantia nigra dopaminergic neurodegeneration in Parkinson's disease (PD), but how these pathways are linked in human neurons remains ... [more ▼]

Mitochondrial and lysosomal dysfunction have been implicated in substantia nigra dopaminergic neurodegeneration in Parkinson's disease (PD), but how these pathways are linked in human neurons remains unclear. Here we studied dopaminergic neurons derived from patients with idiopathic and familial PD. We identified a time-dependent pathological cascade beginning with mitochondrial oxidant stress leading to oxidized dopamine accumulation and ultimately resulting in reduced glucocerebrosidase enzymatic activity, lysosomal dysfunction, and alpha-synuclein accumulation. This toxic cascade was observed in human, but not in mouse, PD neurons at least in part because of species-specific differences in dopamine metabolism. Increasing dopamine synthesis or alpha-synuclein amounts in mouse midbrain neurons recapitulated pathological phenotypes observed in human neurons. Thus, dopamine oxidation represents an important link between mitochondrial and lysosomal dysfunction in PD pathogenesis. [less ▲]

Guidelines for the use and interpretation of assays for monitoring autophagy.

in Autophagy (2012), 8(4), 445-544

In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field ... [more ▼]

In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. A key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process vs. those that measure flux through the autophagy pathway (i.e., the complete process); thus, a block in macroautophagy that results in autophagosome accumulation needs to be differentiated from stimuli that result in increased autophagic activity, defined as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (in most higher eukaryotes and some protists such as Dictyostelium) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the field understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field. [less ▲]