Possible involvement of iron-induced oxidative insults in neurodegeneration.

Involvement of iron in the development of neurodegenerative disorders has long been suggested, and iron that cannot be stored properly is suggested to induce iron toxicity. To enhance iron uptake and suppress iron storage in neurons, we generated transgenic (Tg) mice expressing iron regulatory protein 2 (IRP2), a major regulator of iron metabolism, in a neuron-specific manner. Although very subtle, IRP2 was expressed in all regions of brain examined. In the Tg mice, mitochondrial oxidative insults were observed including generation of 4-hydroxynonenal modified proteins, which appeared to be removed by a mitochondrial quality control protein Parkin. Inter-crossing of the Tg mice to Parkin knockout mice perturbed the integrity of neurons in the substantia nigra and provoked motor symptoms. These results suggest that a subtle, but chronic increase in IRP2 induces mitochondrial oxidative insults and accelerates neurodegeneration in a mouse model of Parkinson's disease. Thus, the IRP2 Tg may be a useful tool to probe the roles of iron-induced mitochondrial damages in neurodegeraration research

Embracing monogenic Parkinson's disease: the MJFF Global Genetic PD Cohort

© 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.Background: As gene-targeted therapies are increasingly being developed for Parkinson's disease (PD), identifying and characterizing carriers of specific genetic pathogenic variants is imperative. Only a small fraction of the estimated number of subjects with monogenic PD worldwide are currently represented in the literature and availability of clinical data and clinical trial-ready cohorts is limited. Objective: The objectives are to (1) establish an international cohort of affected and unaffected individuals with PD-linked variants; (2) provide harmonized and quality-controlled clinical characterization data for each included individual; and (3) further promote collaboration of researchers in the field of monogenic PD. Methods: We conducted a worldwide, systematic online survey to collect individual-level data on individuals with PD-linked variants in SNCA, LRRK2, VPS35, PRKN, PINK1, DJ-1, as well as selected pathogenic and risk variants in GBA and corresponding demographic, clinical, and genetic data. All registered cases underwent thorough quality checks, and pathogenicity scoring of the variants and genotype-phenotype relationships were analyzed. Results: We collected 3888 variant carriers for our analyses, reported by 92 centers (42 countries) worldwide. Of the included individuals, 3185 had a diagnosis of PD (ie, 1306 LRRK2, 115 SNCA, 23 VPS35, 429 PRKN, 75 PINK1, 13 DJ-1, and 1224 GBA) and 703 were unaffected (ie, 328 LRRK2, 32 SNCA, 3 VPS35, 1 PRKN, 1 PINK1, and 338 GBA). In total, we identified 269 different pathogenic variants; 1322 individuals in our cohort (34%) were indicated as not previously published. Conclusions: Within the MJFF Global Genetic PD Study Group, we (1) established the largest international cohort of affected and unaffected individuals carrying PD-linked variants; (2) provide harmonized and quality-controlled clinical and genetic data for each included individual; (3) promote collaboration in the field of genetic PD with a view toward clinical and genetic stratification of patients for gene-targeted clinical trials. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.Michael J. Fox Foundation for Parkinson's Research. Grant Number: ID 15015.02. NIHR Cambridge Biomedical Research Centre. Grant Number: BRC-1215-20014info:eu-repo/semantics/publishedVersio

Defining the causes of sporadic Parkinson's disease in the global Parkinson's genetics program (GP2)

The Global Parkinson’s Genetics Program (GP2) will genotype over 150,000 participants from around the world, and integrate genetic and clinical data for use in large-scale analyses to dramatically expand our understanding of the genetic architecture of PD. This report details the workflow for cohort integration into the complex arm of GP2, and together with our outline of the monogenic hub in a companion paper, provides a generalizable blueprint for establishing large scale collaborative research consortia

Multi-ancestry genome-wide association meta-analysis of Parkinson?s disease

Although over 90 independent risk variants have been identified for Parkinson’s disease using genome-wide association studies, most studies have been performed in just one population at a time. Here we performed a 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 meta-analysis, we identified 78 independent genome-wide significant loci, including 12 potentially novel loci (MTF2, PIK3CA, ADD1, SYBU, IRS2, USP8, PIGL, FASN, MYLK2, USP25, EP300 and PPP6R2) and fine-mapped 6 putative causal variants at 6 known PD loci. By combining our results with publicly available eQTL data, we identified 25 putative risk genes in 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

Isolated nigral degeneration without pathological protein aggregation in autopsied brains with LRRK2 p.R1441H homozygous and heterozygous mutations

Abstract Leucine-rich repeat kinase 2 (LRRK2) is the most common causative gene for autosomal dominant Parkinson’s disease (PD) and is also known to be a susceptibility gene for sporadic PD. Although clinical symptoms with LRRK2 mutations are similar to those in sporadic PD, their pathologies are heterogeneous and include nigral degeneration with abnormal inclusions containing alpha-synuclein, tau, TAR DNA-binding protein 43, and ubiquitin, or pure nigral degeneration with no protein aggregation pathologies. We discovered two families harboring heterozygous and homozygous c.4332 G > A; p.R1441H in LRRK2 with consanguinity, sharing a common founder. They lived in the city of Makurazaki, located in a rural area of the southern region, the Kagoshima prefecture, in Kyushu, Japan. All patients presented late-onset parkinsonism without apparent cognitive decline and demonstrated a good response to levodopa. We obtained three autopsied cases that all presented with isolated nigral degeneration with no alpha-synuclein or other protein inclusions. This is the first report of neuropathological findings in patients with LRRK2 p.R1441H mutations that includes both homozygous and heterozygous mutations. Our findings in this study suggest that isolated nigral degeneration is the primary pathology in patients with LRRK2 p.R1441H mutations, and that protein aggregation of alpha-synuclein or tau might be secondary changes

FBXO7 mutations in Parkinson's disease and multiple system atrophy

Mutations in the F-box only protein 7 (FBXO7) gene, located on chromosome 22q12-q13, have recently been identified as having distinct clinical features in patients with hereditary Parkinson's disease (PD). Pathologically, a-synucleinepositive inclusions have been identified using anti-FBXO7 antibody staining techniques. In the present study, we screened entire exons of FBXO7 from 271 patients (231 PD and 40 multiple system atrophy [MSA]), of which 221 samples were of Japanese origin. The PD patients (n = 231) comprised 31 autosomal dominant, 82 autosomal recessive, and 118 sporadic forms. The 40 cases of MSA consisted of 8 autosomal dominant, 2 autosomal recessive, and 30 sporadic forms. We detected a Turkish patient with autosomal recessive inheritance, harboring a homozygous truncating mutation, Arg498Stop (p.R498X), in the FBXO7 gene. Consequently, we evaluated her and assessed the correlation between her clinical manifestations and genotypic analysis, although the FBXO7 p.R498X gene has lower frequency than others. Her age at onset was 17 years, and she clinically manifested with progressive parkinsonism and cognitive decline. In contrast, no pathogenic mutations in FBXO7 among PD and MSA patients of Japanese or other ethnicities were observed. Based on recent literature, we reviewed and compared the clinical findings and population differences between documented FBXO7 cases. (C) 2016 Elsevier Inc. All rights reserved

Endoscopic treatment of intussusception due to small intestine polyps in patients with Peutz-Jeghers Syndrome

Background and study aims Intussusception caused by intestinal polyps in patients with Peutz-Jeghers syndrome usually requires laparotomy. Patients following successful endoscopic reduction using double-balloon endoscopy (DBE) have been reported. The aim of this study was to evaluate the feasibility of endoscopic treatment of intussusception. Patients and methods We retrospectively reviewed patients who underwent DBE for intussusception due to small intestine polyps in patients with Peutz-Jeghers syndrome from January 2004 to June 2020. Results Twenty-seven (antegrade 22, retrograde 5) DBEs were performed in 19 patients with 25 sites of intussusception identified during the study period. If the intussusception remained once the endoscope reached the site, endoscopic reduction of the intussusception was performed as needed (15 sites). Ultimately, endoscopic resections (8 sites) or ischemic polypectomies (16 sites) of the polyp causing the intussusception were completed at 24 sites. Only one site could not be treated endoscopically and was treated surgically. The final per-site and per-patient success rates of endoscopic treatment were 96 % (24/25) and 95 % (18/19) respectively. Two patients developed mild acute pancreatitis and one patient developed intussusception after the procedures, both of which were treated non-operatively. Conclusions Endoscopic treatment of intussusception is feasible to avoid laparotomy in patients with Peutz-Jeghers syndrome

Screening PARK genes for mutations in early-onset Parkinson's disease patients from Queensland, Australia

A family history of Parkinson's disease (PD) is the most commonly reported risk factor after age, suggesting a genetic component to the disease in a sub-group of patients. Mutations in at least six genes have been identified that can lead to monogenic forms of PD. We screened a sample of 74 early-onset PD cases out of a cohort of 950 patients (onse