La place des céréales dans les habitudes alimentaires des peuples fenniques

Les céréales occupent une place très importante dans l’alimentation des peuples fenniques ; en effet, il est relativement aisé de les conserver plusieurs mois (contrairement à la plupart des légumes), ce qui présente un avantage évident compte tenu de la rudesse des hivers. Que ce soit sous forme de farine ou bien de flocons, les céréales ne demandent qu’un taux d’humidité relativement faible, mais résistent bien aux grands froids comme aux grosses chaleurs (nettement plus rares dans la régio..

Identification of a DAGLB Mutation in a Non-Chinese Patient with Parkinson's Disease

Liu et al. recently reported that biallelic mutations in DAGLB are responsible for autosomal recessive early-onset Parkinson's disease. They identified six patients carrying DAGLB mutations, all of Chinese origin and presenting with typical Parkinson disease. No additional cases outside China have been reported so far.To assess the causality of DAGLB in our cohort, we used data mining in the exomes of 684 index cases with either autosomal recessive or sporadic early onset Parkinson disease (< 50 years). We identified a homozygous p.Pro357Leu missense variant in a single consanguineous PD case. This mutation predicted deleterious, affects a conserved amino acid localized in the catalytic domain of the protein nearby the pathological p.Asp363Gly mutation described in the previous paper. As the most frequent genes involved in AR-PD (PRKN, PINK1), the DAGLB-associated disease presents and evolves like typical PD.This work reinforces the fact that DAGLB is involved in early onset Parkinson disease, but given the fact that we identified a single patient among 684 index cases screened, we conclude that DAGLB is a very rare cause of early onset autosomal recessive Parkinson disease. However, we demonstrate that, mutations in DAGLB are not limited to the Chinese population but can also account for PD in North Africa.We feel that these new data indicate that DAGLB variants should be considered in non-Chinese cases with early-onset typical Parkinson disease

Failure to Censor Forbidden Clones of CD4 T Cells in Autoimmune Diabetes

Type 1 diabetes and other organ-specific autoimmune diseases often cluster together in human families and in congenic strains of NOD (nonobese diabetic) mice, but the inherited immunoregulatory defects responsible for these diseases are unknown. Here we track the fate of high avidity CD4 T cells recognizing a self-antigen expressed in pancreatic islet β cells using a transgenic mouse model. T cells of identical specificity, recognizing a dominant peptide from the same islet antigen and major histocompatibility complex (MHC)-presenting molecule, were followed on autoimmune susceptible and resistant genetic backgrounds. We show that non-MHC genes from the NOD strain cause a failure to delete these high avidity autoreactive T cells during their development in the thymus, with subsequent spontaneous breakdown of CD4 cell tolerance to the islet antigen, formation of intra-islet germinal centers, and high titre immunoglobulin G1 autoantibody production. In mixed bone marrow chimeric animals, defective thymic deletion was intrinsic to T cells carrying diabetes susceptibility genes. These results demonstrate a primary failure to censor forbidden clones of self-reactive T cells in inherited susceptibility to organ-specific autoimmune disease, and highlight the importance of thymic mechanisms of tolerance in organ-specific tolerance

A Deleterious Mutation in DNAJC6 Encoding the Neuronal-Specific Clathrin-Uncoating Co-Chaperone Auxilin, Is Associated with Juvenile Parkinsonism

Parkinson disease is caused by neuronal loss in the substantia nigra which manifests by abnormality of movement, muscle tone, and postural stability. Several genes have been implicated in the pathogenesis of Parkinson disease, but the underlying molecular basis is still unknown for ∼70% of the patients. Using homozygosity mapping and whole exome sequencing we identified a deleterious mutation in DNAJC6 in two patients with juvenile Parkinsonism. The mutation was associated with abnormal transcripts and marked reduced DNAJC6 mRNA level. DNAJC6 encodes the HSP40 Auxilin, a protein which is selectively expressed in neurons and confers specificity to the ATPase activity of its partner Hcs70 in clathrin uncoating. In Auxilin null mice it was previously shown that the abnormally increased retention of assembled clathrin on vesicles and in empty cages leads to impaired synaptic vesicle recycling and perturbed clathrin mediated endocytosis. Endocytosis function, studied by transferring uptake, was normal in fibroblasts from our patients, likely because of the presence of another J-domain containing partner which co-chaperones Hsc70-mediated uncoating activity in non-neuronal cells. The present report underscores the importance of the endocytic/lysosomal pathway in the pathogenesis of Parkinson disease and other forms of Parkinsonism

Editorial: Celebrating the Diversity of Genetic Research to Dissect the Pathogenesis of Parkinson's Disease

Parkinson's disease (PD) is the fastest growing neurological disorder worldwide, taking into account age-standardized rates for prevalence, disability and deaths (1). PD is characterized by a clinical symptomatology involving both motor and non-motor symptoms. According to the Global Burden of Disease study (2018), the global burden of this disorder has more than doubled over the past two decades from 2.5 million patients in 1990 to 6.1 million patients in 2016 (2). In this editorial and eBook, we highlight the research done on PD by members of a global consortium known as the Genetic Epidemiology of Parkinson's disease (GEoPD) Consortium. We begin the editorial by providing a brief history of how GEoPD was started and how it has subsequently developed into an international endeavor. We then briefly summarize the completed and ongoing projects, and conclude with the future vision of this unique consortium

EIF4G1 in familial Parkinson's disease: pathogenic mutations or rare benign variants?

International audienceMutations in the eukaryotic translation initiation factor 4-gamma (EIF4G1) gene, encoding a component of the eIF4F translation initiation complex, were recently reported as a possible cause for the autosomal dominant form of Parkinson's disease (PD). Here, we describe the screening of all 31 EIF4G1 coding exons in a series of 251 index cases with autosomal dominant PD, mostly of French origin and in 236 European control subjects. We identified 12 rare coding variants (either nonsynonymous amino acid substitutions or in frame deletions/insertions), including 6 variants present only in cases and 3 in controls. Segregation was possible only for 1 variant (p.E462delInsGK) that was found in 2 affected siblings. In addition, we found 2 previously reported pathogenic variants in 2 isolated patients (p.G686C) and in a control subject (p.R1197W). These data do not support the pathogenicity of several EIF4G1 variants in PD, at least in the French population

A systematic screening to identifyde novomutations causing sporadic early-onset Parkinson's disease

Despite the many advances in our understanding of the genetic basis of Mendelian forms of Parkinson's disease (PD), a large number of early-onset cases still remain to be explained. Many of these cases, present with a form of disease that is identical to that underlined by genetic causes, but do not have mutations in any of the currently known disease-causing genes. Here, we hypothesized that de novo mutations may account for a proportion of these early-onset, sporadic cases. We performed exome sequencing in full parent-child trios where the proband presents with typical PD to unequivocally identify de novo mutations. This approach allows us to test all genes in the genome in an unbiased manner. We have identified and confirmed 20 coding de novo mutations in 21 trios. We have used publicly available population genetic data to compare variant frequencies and our independent in-house dataset of exome sequencing in PD (with over 1200 cases) to identify additional variants in the same genes. Of the genes identified to carry de novo mutations, PTEN, VAPB and ASNA1 are supported by various sources of data to be involved in PD. We show that these genes are reported to be within a protein-protein interaction network with PD genes and that they contain additional rare, case-specific, mutations in our independent cohort of PD cases. Our results support the involvement of these three genes in PD and suggest that testing for de novo mutations in sporadic disease may aid in the identification of novel disease-causing genes

Underrepresented Populations in Parkinson's Genetics Research: Current Landscape and Future Directions

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

Additional rare variant analysis in Parkinson's Disease cases with and without known pathogenic mutations: evidence for oligogenic inheritance

Oligogenic inheritance implies a role for several genetic factors in disease etiology. We studied oligogenic inheritance in Parkinson’s (PD) by assessing the potential burden of additional rare variants in established Mendelian genes and/or GBA, in individuals with and without a primary pathogenic genetic cause in two large independent cohorts totaling 7,900 PD cases and 6,166 controls. An excess (≥30%) of cases with a recognized primary genetic cause had ≥1 additional rare variants in Mendelian PD genes, as compared with no known mutation PD cases (17%) and unaffected controls (16%), supporting our hypothesis. Carriers of additional Mendelian gene variants have younger ages at onset (AAO). The effect of additional Mendelian variants in LRRK2 G2019S mutation carriers, of which ATP13A2 variation is particularly common, may account for some of the variation in penetrance. About 10% of no known mutation PD cases harbor a rare GBA variant compared to known pathogenic mutation PD cases (8%) and controls (5%), with carriers having earlier AAOs. Together, the data suggest that the oligogenic inheritance of rare Mendelian variants may be important in patient with a primary pathogenic cause, whereas GBA increases risk across all forms of PD. This study highlights potential genetic complexity of Mendelian PD. The identification of potential modifying variants provides new insights into disease mechanisms by potentially separating relevant from benign variants and by the interaction between genes in specific pathways. In the future this may be relevant to genetic testing and counselling of PD patients and their families