Several pathogenic mutations in the leucine-rich repeat kinase 2 (LRRK2; PARK8) gene recently have been identified in familial and sporadic parkinsonism. We screened 435 Norwegian patients diagnosed with Parkinson's disease and 519 control subjects for the presence of 7 LRRK2 mutations. Nine patients from seven families were found to be heterozygote carriers of the LRRK2 6055G>A (G2019S) mutation. Twelve of 28 first-degree relatives also carried the mutation, but only 1 had Parkinson's disease. The clinical features included asymmetric resting tremor, bradykinesia, and rigidity with a good response to levodopa and could not be distinguished from idiopathic Parkinson's disease.

Although over 90 independent risk variants have been identified for Parkinson's disease using genome-wide association studies, all studies have been performed in just one population at the time. Here we performed the first large-scale multi-ancestry meta-analysis of Parkinson's disease with 49,049 cases, 18,785 proxy cases, and 2,458,063 controls including individuals of European, East Asian, Latin American, and African ancestry. In a single joint meta-analysis, we identified 78 independent genome-wide significant loci including 12 potentially novel loci (MTF2, RP11-360P21.2, ADD1, SYBU, IRS2, USP8:RP11-562A8.5, PIGL, FASN, MYLK2, AJ006998.2, Y_RNA, PPP6R2) and finemapped 6 putative causal variants at 6 known PD loci. By combining our results with publicly available eQTL data, we identified 23 genes near these novel loci whose expression is associated with PD risk. This work lays the groundwork for future efforts aimed at identifying PD loci in non-European populations.

Background Human genetics research lacks diversity; over 80% of genome‐wide association studies have been conducted on individuals of European ancestry. In addition to limiting insights regarding disease mechanisms, disproportionate representation can create disparities preventing equitable implementation of personalized medicine. Objective This systematic review provides an overview of research involving Parkinson's disease (PD) genetics in underrepresented populations (URP) and sets a baseline to measure the future impact of current efforts in those populations. Methods We searched PubMed and EMBASE until October 2021 using search strings for “PD,” “genetics,” the main “URP,” and and the countries in Latin America, Caribbean, Africa, Asia, and Oceania (excluding Australia and New Zealand). Inclusion criteria were original studies, written in English, reporting genetic results on PD from non‐European populations. Two levels of independent reviewers identified and extracted information. Results We observed imbalances in PD genetic studies among URPs. Asian participants from Greater China were described in the majority of the articles published (57%), but other populations were less well studied; for example, Blacks were represented in just 4.0% of the publications. Also, although idiopathic PD was more studied than monogenic forms of the disease, most studies analyzed a limited number of genetic variants. We identified just nine studies using a genome‐wide approach published up to 2021, including URPs. Conclusion This review provides insight into the significant lack of population diversity in PD research highlighting the immediate need for better representation. The Global Parkinson's Genetics Program (GP2) and similar initiatives aim to impact research in URPs, and the early metrics presented here can be used to measure progress in the field of PD genetics in the future. © 2022 International Parkinson and Movement Disorder Society.

Background Parkinson's disease is the second most common neurodegenerative disorder and affects people from all ethnic backgrounds, yet little is known about the genetics of Parkinson's disease in non‐European populations. In addition, the overall identification of copy number variants at a genome‐wide level has been understudied in Parkinson's patients. The objective of this study was to understand the genome‐wide burden of copy number variants in Latinos and its association with Parkinson's disease. Methods We used genome‐wide genotyping data from 747 Parkinson's disease patients and 632 controls from the Latin American Research Consortium on the Genetics of Parkinson's disease. Results Genome‐wide copy number burden analysis showed that patients were significantly enriched for copy number variants overlapping known Parkinson's disease genes compared with controls (odds ratio, 3.97; 95%CI, 1.69–10.5; P = 0.018). PRKN showed the strongest copy number burden, with 20 copy number variant carriers. These patients presented an earlier age of disease onset compared with patients with other copy number variants (median age at onset, 31 vs 57 years, respectively; P = 7.46 × 10−7). Conclusions We found that although overall genome‐wide copy number variant burden was not significantly different, Parkinson's disease patients were significantly enriched with copy number variants affecting known Parkinson's disease genes. We also identified that of 250 patients with early‐onset disease, 5.6% carried a copy number variant on PRKN in our cohort. Our study is the first to analyze genome‐wide copy number variant association in Latino Parkinson's disease patients and provides insights about this complex disease in this understudied population. © 2020 International Parkinson and Movement Disorder Society