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BACKGROUND AND OBJECTIVES: The role of body mass index (BMI) in Parkinson disease (PD) is unclear. Based on the Comprehensive Unbiased Risk Factor Assessment for Genetics and Environment in PD (Courage-PD) consortium, we used 2-sample Mendelian randomization (MR) to replicate a previously reported inverse association of genetically predicted BMI with PD and investigated whether findings were robust in analyses addressing the potential for survival and incidence-prevalence biases. We also examined whether the BMI-PD relation is bidirectional by performing a reverse MR. METHODS: We used summary statistics from a genome-wide association study (GWAS) to extract the association of 501 single-nucleotide polymorphisms (SNPs) with BMI and from the Courage-PD and international Parkinson Disease Genomics Consortium (iPDGC) to estimate their association with PD. Analyses are based on participants of European ancestry. We used the inverse-weighted method to compute odds ratios (ORIVW per 4.8 kg/m2 [95% CI]) of PD and additional pleiotropy robust methods. We performed analyses stratified by age, disease duration, and sex. For reverse MR, we used SNPs associated with PD from 2 iPDGC GWAS to assess the effect of genetic liability toward PD on BMI. RESULTS: Summary statistics for BMI are based on 806,834 participants (54% women). Summary statistics for PD are based on 8,919 (40% women) cases and 7,600 (55% women) controls from Courage-PD, and 19,438 (38% women) cases and 24,388 (51% women) controls from iPDGC. In Courage-PD, we found an inverse association between genetically predicted BMI and PD (ORIVW 0.82 [0.70-0.97], p = 0.012) without evidence for pleiotropy. This association tended to be stronger in younger participants (≤67 years, ORIVW 0.71 [0.55-0.92]) and cases with shorter disease duration (≤7 years, ORIVW 0.75 [0.62-0.91]). In pooled Courage-PD + iPDGC analyses, the association was stronger in women (ORIVW 0.85 [0.74-0.99], p = 0.032) than men (ORIVW 0.92 [0.80-1.04], p = 0.18), but the interaction was not statistically significant (p-interaction = 0.48). In reverse MR, there was evidence for pleiotropy, but pleiotropy robust methods showed a significant inverse association. DISCUSSION: Using an independent data set (Courage-PD), we replicate an inverse association of genetically predicted BMI with PD, not explained by survival or incidence-prevalence biases. Moreover, reverse MR analyses support an inverse association between genetic liability toward PD and BMI, in favor of a bidirectional relation.
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Índice de Masa Corporal , Estudio de Asociación del Genoma Completo , Análisis de la Aleatorización Mendeliana , Enfermedad de Parkinson , Polimorfismo de Nucleótido Simple , Humanos , Enfermedad de Parkinson/genética , Enfermedad de Parkinson/epidemiología , Polimorfismo de Nucleótido Simple/genética , Femenino , Masculino , Persona de Mediana Edad , Anciano , Factores de RiesgoRESUMEN
Despite substantial progress, causal variants are identified only for a minority of familial Parkinson's disease (PD) cases, leaving high-risk pathogenic variants unidentified1,2. To identify such variants, we uniformly processed exome sequencing data of 2,184 index familial PD cases and 69,775 controls. Exome-wide analyses converged on RAB32 as a novel PD gene identifying c.213C > G/p.S71R as a high-risk variant presenting in ~0.7% of familial PD cases while observed in only 0.004% of controls (odds ratio of 65.5). This variant was confirmed in all cases via Sanger sequencing and segregated with PD in three families. RAB32 encodes a small GTPase known to interact with LRRK2 (refs. 3,4). Functional analyses showed that RAB32 S71R increases LRRK2 kinase activity, as indicated by increased autophosphorylation of LRRK2 S1292. Here our results implicate mutant RAB32 in a key pathological mechanism in PD-LRRK2 kinase activity5-7-and thus provide novel insights into the mechanistic connections between RAB family biology, LRRK2 and PD risk.
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Predisposición Genética a la Enfermedad , Proteína 2 Quinasa Serina-Treonina Rica en Repeticiones de Leucina , Enfermedad de Parkinson , Proteínas de Unión al GTP rab , Humanos , Enfermedad de Parkinson/genética , Proteínas de Unión al GTP rab/genética , Proteína 2 Quinasa Serina-Treonina Rica en Repeticiones de Leucina/genética , Femenino , Masculino , Linaje , Persona de Mediana Edad , Mutación , Exoma/genética , Secuenciación del Exoma , Estudios de Casos y Controles , AncianoRESUMEN
Loss-of-function CHD2 (chromodomain helicase DNA-binding protein 2) mutations are associated with a spectrum of neurodevelopmental disorders often including early-onset generalized seizures, photosensitivity, and epileptic encephalopathies. Patients show psychomotor delay/intellectual disability (ID), autistic features, and behavior disorders, such as aggression and impulsivity. Most reported cases are sporadic with description of germline mosaicism only in two families. We detect the first case of parental gonosomal CHD2 mosaicism disclosed by two brothers showing mild ID, born to healthy parents. The eldest brother has a history of drug-controlled generalized tonic-clonic seizures and displays sleep disorder and aggressive behavior suggestive of Smith-Magenis syndrome (SMS). Analysis of brothers' DNAs by next-generation sequencing (NGS) custom gene panel for pediatric epilepsy and/or ID disclosed in both the same pathogenic CHD2 variant. Additional NGS experiment on genomic DNA from parents' peripheral blood and from buccal swab raised the suspicion of low-grade gonosomal mosaicism in the unaffected mother subsequently confirmed by digital polymerase chain reaction (dPCR). This report underlines as worthwhile CHD2 screening in individuals presenting ID/developmental delay, with/without epilepsy, and behavior and sleep disorders suggestive of SMS. Detecting a CHD2 variant should prime testing probands' parents by NGS coupled to dPCR on different tissues to exclude/confirm gonosomal mosaicism and define the recurrence risk.
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Mosaicismo , Hermanos , Síndrome de Smith-Magenis , Humanos , Masculino , Síndrome de Smith-Magenis/genética , Proteínas de Unión al ADN/genética , Femenino , Discapacidad Intelectual/genética , Niño , Secuenciación de Nucleótidos de Alto Rendimiento/métodos , Linaje , Mutación/genética , Preescolar , FenotipoRESUMEN
BACKGROUND: Epidemiological studies that examined the association between Parkinson's disease (PD) and cancers led to inconsistent results, but they face a number of methodological difficulties. OBJECTIVE: We used results from genome-wide association studies (GWASs) to study the genetic correlation between PD and different cancers to identify common genetic risk factors. METHODS: We used individual data for participants of European ancestry from the Courage-PD (Comprehensive Unbiased Risk Factor Assessment for Genetics and Environment in Parkinson's Disease; PD, N = 16,519) and EPITHYR (differentiated thyroid cancer, N = 3527) consortia and summary statistics of GWASs from iPDGC (International Parkinson Disease Genomics Consortium; PD, N = 482,730), Melanoma Meta-Analysis Consortium (MMAC), Breast Cancer Association Consortium (breast cancer), the Prostate Cancer Association Group to Investigate Cancer Associated Alterations in the Genome (prostate cancer), International Lung Cancer Consortium (lung cancer), and Ovarian Cancer Association Consortium (ovarian cancer) (N comprised between 36,017 and 228,951 for cancer GWASs). We estimated the genetic correlation between PD and cancers using linkage disequilibrium score regression. We studied the association between PD and polymorphisms associated with cancers, and vice versa, using cross-phenotypes polygenic risk score (PRS) analyses. RESULTS: We confirmed a previously reported positive genetic correlation of PD with melanoma (Gcorr = 0.16 [0.04; 0.28]) and reported an additional significant positive correlation of PD with prostate cancer (Gcorr = 0.11 [0.03; 0.19]). There was a significant inverse association between the PRS for ovarian cancer and PD (odds ratio [OR] = 0.89 [0.84; 0.94]). Conversely, the PRS of PD was positively associated with breast cancer (OR = 1.08 [1.06; 1.10]) and inversely associated with ovarian cancer (OR = 0.95 [0.91; 0.99]). The association between PD and ovarian cancer was mostly driven by rs183211 located in an intron of the NSF gene (17q21.31). CONCLUSIONS: We show evidence in favor of a contribution of pleiotropic genes to the association between PD and specific cancers. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.
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Neoplasias Pulmonares , Melanoma , Neoplasias Ováricas , Enfermedad de Parkinson , Neoplasias de la Próstata , Humanos , Masculino , Femenino , Enfermedad de Parkinson/epidemiología , Enfermedad de Parkinson/genética , Estudio de Asociación del Genoma Completo , Predisposición Genética a la Enfermedad/genética , Polimorfismo de Nucleótido Simple/genética , Melanoma/epidemiología , Melanoma/genética , Factores de RiesgoRESUMEN
BACKGROUND AND OBJECTIVES: Considerable heterogeneity exists in the literature concerning genetic determinants of the age at onset (AAO) of Parkinson disease (PD), which could be attributed to a lack of well-powered replication cohorts. The previous largest genome-wide association studies (GWAS) identified SNCA and TMEM175 loci on chromosome (Chr) 4 with a significant influence on the AAO of PD; these have not been independently replicated. This 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's Disease (COURAGE-PD) Consortium. This was followed 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 Consortium included a cohort of 8,535 patients with PD (91.9%: Europeans and 9.1%: East Asians). The average AAO in the COURAGE-PD dataset was 58.9 years (SD = 11.6), with an underrepresentation 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 < 5 × 10-8). Nevertheless, the COURAGE-PD dataset confirmed the role of the previously published TMEM175 variant as a genetic determinant of the AAO of PD with Bonferroni-corrected nominal levels of significance (p < 0.025): (rs34311866: ß(SE)COURAGE = 0.477(0.203), p COURAGE = 0.0185). The subsequent meta-analysis of COURAGE-PD and IPDGC datasets (Ntotal = 25,950) led to the identification of 2 genome-wide significant association signals on Chr 4, including the previously reported SNCA locus (rs983361: ß(SE)COURAGE+IPDGC = 0.720(0.122), p COURAGE+IPDGC = 3.13 × 10-9) and a novel BST1 locus (rs4698412: ß(SE)COURAGE+IPDGC = -0.526(0.096), p COURAGE+IPDGC = 4.41 × 10-8). 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.
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Coraje , Enfermedad de Parkinson , Edad de Inicio , Femenino , Predisposición Genética a la Enfermedad/genética , Estudio de Asociación del Genoma Completo , Humanos , Enfermedad de Parkinson/epidemiología , Enfermedad de Parkinson/genética , Polimorfismo de Nucleótido SimpleRESUMEN
ß-glucocerebrosidase is a lysosomal hydrolase involved in the catabolism of the sphingolipid glucosylceramide. Biallelic loss of function mutations in this enzyme are responsible for the onset of Gaucher disease, while monoallelic ß-glucocerebrosidase mutations represent the first genetic risk factor for Parkinson's disease. Despite this evidence, the molecular mechanism linking the impairment in ß-glucocerebrosidase activity with the onset of neurodegeneration in still unknown. In this frame, we developed two in vitro neuronal models of ß-glucocerebrosidase deficiency, represented by mouse cerebellar granule neurons and human-induced pluripotent stem cells-derived dopaminergic neurons treated with the specific ß-glucocerebrosidase inhibitor conduritol B epoxide. Neurons deficient for ß-glucocerebrosidase activity showed a lysosomal accumulation of glucosylceramide and the onset of neuronal damage. Moreover, we found that neurons react to the lysosomal impairment by the induction of their biogenesis and exocytosis. This latter event was responsible for glucosylceramide accumulation also at the plasma membrane level, with an alteration in lipid and protein composition of specific signaling microdomains. Collectively, our data suggest that ß-glucocerebrosidase loss of function impairs the lysosomal compartment, establishing a lysosome-plasma membrane axis responsible for modifications in the plasma membrane architecture and possible alterations of intracellular signaling pathways, leading to neuronal damage.
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Enfermedad de Gaucher , Glucosilceramidasa , Animales , Membrana Celular/metabolismo , Neuronas Dopaminérgicas/metabolismo , Enfermedad de Gaucher/genética , Enfermedad de Gaucher/metabolismo , Glucosilceramidasa/genética , Glucosilceramidasa/metabolismo , Glucosilceramidas , Humanos , Lisosomas/metabolismo , RatonesRESUMEN
BACKGROUND: Two studies that examined the interaction between HLA-DRB1 and smoking in Parkinson's disease (PD) yielded findings in opposite directions. OBJECTIVE: To perform a large-scale independent replication of the HLA-DRB1 × smoking interaction. METHODS: We genotyped 182 single nucleotide polymorphism (SNPs) associated with smoking initiation in 12 424 cases and 9480 controls to perform a Mendelian randomization (MR) analysis in strata defined by HLA-DRB1. RESULTS: At the amino acid level, a valine at position 11 (V11) in HLA-DRB1 displayed the strongest association with PD. MR showed an inverse association between genetically predicted smoking initiation and PD only in absence of V11 (odds ratio, 0.74, 95% confidence interval, 0.59-0.93, PInteraction = 0.028). In silico predictions of the influence of V11 and smoking-induced modifications of α-synuclein on binding affinity showed findings consistent with this interaction pattern. CONCLUSIONS: Despite being one of the most robust findings in PD research, the mechanisms underlying the inverse association between smoking and PD remain unknown. Our findings may help better understand this association. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.
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Enfermedad de Parkinson , Predisposición Genética a la Enfermedad , Cadenas HLA-DRB1/genética , Humanos , Enfermedad de Parkinson/genética , Polimorfismo de Nucleótido Simple/genética , Fumar/genéticaRESUMEN
Niemann-Pick type A disease (NPA) is a rare lysosomal storage disorder caused by mutations in the gene coding for the lysosomal enzyme acid sphingomyelinase (ASM). ASM deficiency leads to the consequent accumulation of its uncatabolized substrate, the sphingolipid sphingomyelin (SM), causing severe progressive brain disease. To study the effect of the aberrant lysosomal accumulation of SM on cell homeostasis, we loaded skin fibroblasts derived from a NPA patient with exogenous SM to mimic the levels of accumulation characteristic of the pathological neurons. In SM-loaded NPA fibroblasts, we found the blockage of the autophagy flux and the impairment of the mitochondrial compartment paralleled by the altered transcription of several genes, mainly belonging to the electron transport chain machinery and to the cholesterol biosynthesis pathway. In addition, SM loading induces the nuclear translocation of the transcription factor EB that promotes the lysosomal biogenesis and exocytosis. Interestingly, we obtained similar biochemical findings in the brain of the NPA mouse model lacking ASM (ASMKO mouse) at the neurodegenerative stage. Our work provides a new in vitro model to study NPA etiopathology and suggests the existence of a pathogenic lysosome-plasma membrane axis that with an impairment in the mitochondrial activity is responsible for the cell death.
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Enfermedad de Niemann-Pick Tipo A , Enfermedades de Niemann-Pick , Animales , Apoptosis , Lisosomas/metabolismo , Ratones , Mitocondrias/metabolismo , Enfermedad de Niemann-Pick Tipo A/genética , Enfermedad de Niemann-Pick Tipo A/patología , Enfermedades de Niemann-Pick/metabolismo , Enfermedades de Niemann-Pick/patología , Esfingomielinas/metabolismo , Esfingomielinas/farmacologíaRESUMEN
BACKGROUND: To date, variants in the GBA gene represent the most frequent large-effect genetic factor associated with Parkinson's disease (PD). However, the reason why individuals with the same GBA variant may or may not develop neurodegeneration and PD is still unclear. OBJECTIVES: Therefore, we evaluated the contribution of rare variants in genes responsible for lysosomal storage disorders (LSDs) to GBA-PD risk, comparing the burden of deleterious variants in LSD genes in PD patients versus asymptomatic subjects, all carriers of deleterious variants in GBA. METHODS: We used a custom next-generation sequencing panel, including 50 LSD genes, to screen 305 patients and 207 controls (discovery cohort). Replication and meta-analysis were performed in two replication cohorts of GBA-variant carriers, of 250 patients and 287 controls, for whom exome or genome data were available. RESULTS: Statistical analysis in the discovery cohort revealed a significantly increased burden of deleterious variants in LSD genes in patients (P = 0.0029). Moreover, our analyses evidenced that the two strongest modifiers of GBA penetrance are a second variation in GBA (5.6% vs. 1.4%, P = 0.023) and variants in genes causing mucopolysaccharidoses (6.9% vs. 1%, P = 0.0020). These results were confirmed in the meta-analysis, where we observed pooled odds ratios of 1.42 (95% confidence interval [CI] = 1.10-1.83, P = 0.0063), 4.36 (95% CI = 2.02-9.45, P = 0.00019), and 1.83 (95% CI = 1.04-3.22, P = 0.038) for variants in LSD genes, GBA, and mucopolysaccharidosis genes, respectively. CONCLUSION: The identification of genetic lesions in lysosomal genes increasing PD risk may have important implications in terms of patient stratification for future therapeutic trials. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson Movement Disorder Society.
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Enfermedad de Parkinson , Humanos , Glucosilceramidasa/genética , Heterocigoto , Lisosomas , Mutación , Enfermedad de Parkinson/complicaciones , Enfermedad de Parkinson/genéticaRESUMEN
BACKGROUND: Previous prospective studies highlighted dairy intake as a risk factor for Parkinson's disease (PD), particularly in men. It is unclear whether this association is causal or explained by reverse causation or confounding. OBJECTIVE: The aim is to examine the association between genetically predicted dairy intake and PD using two-sample Mendelian randomization (MR). METHODS: We genotyped a well-established instrumental variable for dairy intake located in the lactase gene (rs4988235) within the Courage-PD consortium (23 studies; 9823 patients and 8376 controls of European ancestry). RESULTS: Based on a dominant model, there was an association between genetic predisposition toward higher dairy intake and PD (odds ratio [OR] per one serving per day = 1.70, 95% confidence interval = 1.12-2.60, P = 0.013) that was restricted to men (OR = 2.50 [1.37-4.56], P = 0.003; P-difference with women = 0.029). CONCLUSIONS: Using MR, our findings provide further support for a causal relationship between dairy intake and higher PD risk, not biased by confounding or reverse causation. Further studies are needed to elucidate the underlying mechanisms. © 2022 International Parkinson and Movement Disorder Society.
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Enfermedad de Parkinson , Productos Lácteos/efectos adversos , Femenino , Predisposición Genética a la Enfermedad/genética , Estudio de Asociación del Genoma Completo , Humanos , Masculino , Análisis de la Aleatorización Mendeliana , Enfermedad de Parkinson/epidemiología , Enfermedad de Parkinson/genética , Polimorfismo de Nucleótido Simple/genética , Factores de RiesgoRESUMEN
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 (pâ=â0.017). RESULTS: We found a significant inverse association between smoking initiation and PD (ORIVW per 1-SD increase in the prevalence of ever smokingâ=â0.74, 95%CIâ=â0.60-0.93, pâ=â0.009) 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.
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Café , Enfermedad de Parkinson , Anciano , Consumo de Bebidas Alcohólicas/epidemiología , Consumo de Bebidas Alcohólicas/genética , Estudio de Asociación del Genoma Completo , Humanos , Análisis de la Aleatorización Mendeliana , Enfermedad de Parkinson/etiología , Enfermedad de Parkinson/genética , Factores de Riesgo , Fumar/epidemiologíaRESUMEN
INTRODUCTION: Parkinson's disease (PD) belongs to a family of neurodegenerative diseases characterized by alpha-synuclein accumulation in neurons, whose etiopathogenesis remains largely uncovered. Recently, LRP10 has been associated with PD, Parkinson's disease Dementia (PDD) and Dementia with Lewy Bodies (DLB) by linkage analysis and positional cloning in an Italian family with late-onset PD. After the first characterization of a LRP10 pathogenic variant, other eight mutations have been detected in an international series of 660 probands with either a clinical or pathological diagnosis of PD, PDD or DLB. However, the results of following replication studies were inconclusive and the pathogenic role of LRP10 is still debated. The aim of this study is to sequence the LRP10 gene in an Italian cohort of clinically-diagnosed PD patients and to compare the frequency of the identified variants with the ones found in a large cohort of Italian exomes. METHODS: A cohort of 664 PD patients was analyzed by targeted Next Generation Sequencing approach. Identified LRP10 variants were subsequently confirmed by Sanger sequencing and searched for in an in-house database including 3596 Italian exomes. RESULTS: We identified three PD patients carrying a rare heterozygous, potentially pathogenic variant (p.R296C, p.R549Q, p.R661C). None of them was detected in 3596 Italian exomes. Two of them (p.R296C and p.R661C) have been previously reported in one sporadic PD and one definite Progressive supranuclear palsy patients respectively. All three carriers had late-onset PD responsive to levodopa, characterized by both motor and non-motor features, but no cognitive impairment. CONCLUSION: We report three rare possibly-pathogenic LRP10 variants in PD patients from Italy. Further investigations are required to definitively establish their role in alpha-synucleinopathies.
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Proteínas Relacionadas con Receptor de LDL/genética , Enfermedad de Parkinson/genética , Anciano , Femenino , Secuenciación de Nucleótidos de Alto Rendimiento , Humanos , Italia , Masculino , Persona de Mediana Edad , Secuenciación del ExomaRESUMEN
In this work, we describe the association of a novel homozygous VPS11 variant with adult-onset generalized dystonia, providing a detailed clinical report and biological evidence of disease mechanism. Vps11 is a subunit of the homotypic fusion and protein sorting (HOPS) complex, which promotes the fusion of late endosomes and autophagosomes with the lysosome. Functional studies on mutated fibroblasts showed marked lysosomal and autophagic abnormalities, which improved after overexpression of the wild type Vps11 protein. In conclusion, a deleterious VPS11 variant, damaging the autophagic and lysosomal pathways, is the probable genetic cause of a novel form of generalized dystonia. ANN NEUROL 2021;89:834-839.
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Distonía/genética , Proteínas de Transporte Vesicular/genética , Adulto , Edad de Inicio , Secuencia de Aminoácidos , Autofagia/genética , Encéfalo/diagnóstico por imagen , ADN/genética , Distonía/diagnóstico por imagen , Distonía/etiología , Endosomas/patología , Fibroblastos/patología , Variación Genética , Homocigoto , Humanos , Lisosomas/patología , Imagen por Resonancia Magnética , Mutación , Linaje , Fagosomas/patología , Secuenciación del ExomaRESUMEN
OBJECTIVE: To provide a variant-specific estimate of incidence, penetrance, sex distribution, and association with dementia of the 4 most common Parkinson disease (PD)-associated GBA variants, we analyzed a large cohort of 4,923 Italian unrelated patients with primary degenerative parkinsonism (including 3,832 PD) enrolled in a single tertiary care center and 7,757 ethnically matched controls. METHODS: The p.E326K, p.T369M, p.N370S, and p.L444P variants were screened using an allele-specific multiplexed PCR approach. All statistical procedures were performed using R or Plink v1.07. RESULTS: Among the 4 analyzed variants, the p.L444P confirmed to be the most strongly associated with disease risk for PD, PD dementia (PDD), and dementia with Lewy bodies (DLB) (odds ratio [OR] for PD 15.63, 95% confidence interval [CI] = 8.04-30.37, p = 4.97*10-16; OR for PDD 29.57, 95% CI = 14.07-62.13, p = 3.86*10-19; OR for DLB 102.7, 95% CI = 31.38-336.1, p = 1.91*10-14). However, an unexpectedly high risk for dementia was conferred by p.E326K (OR for PDD 4.80, 95% CI = 2.87-8.02, p = 2.12*10-9; OR for DLB 12.24, 95% CI = 4.95-30.24, p = 5.71*10-8), which, on the basis of the impact on glucocerebrosidase activity, would be expected to be mild. The 1.5-2:1 male sex bias described in sporadic PD was lost in p.T369M carriers. We also showed that PD penetrance for p.L444P could reach the 15% at age 75 years. CONCLUSIONS: We report a large monocentric study on GBA-PD assessing mutation-specific data on the sex distribution, penetrance, incidence, and association with dementia of the 4 most frequent deleterious variants in GBA.
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INTRODUCTION: Deleterious variants in the GBA gene confer a 2- to 20-fold increased risk of Parkinson's disease (PD) and are associated with a more severe disease course. The presence of a highly-similar pseudogene complicates genetic screening, both by Sanger and next-generation sequencing (NGS). Among PD-associated GBA variants, four missense substitutions (p.L444P, p.N370S, p.T369M, p.E326K) account for the majority of cases. Here, we aimed at developing an allele-specific PCR (AS-PCR) able to concomitantly detect the most common PD-related GBA variants. METHODS: A multiplex PCR assay was designed using allele-specific oligonucleotides that distinguish the gene from the pseudogene and can exclusively amplify the variant alleles. Primer sequences and molarity, and thermal profiles were empirically optimized. The assay was validated on 4016 DNAs extracted by standard salting-out and previously analyzed by whole-exome sequencing (WES) followed by Sanger validation. RESULTS: AS-PCRs performed on 4016 DNAs detected 103 variants; among them, 97 were true positives and 6 false positives. When comparing the results with the original WES data, for the "difficult" p.L444P, the number of false positives was 2/9 and 18/24 for multiplex-AS-PCR and WES, respectively. As we could have missed some p.L444P alleles by NGS, we verified the test performance on 50 DNAs from Sanger-validated p.L444P heterozygotes. All samples tested correctly. CONCLUSION: We set up and validated a rapid and inexpensive test for screening large cohorts of individuals for variants conferring a significant PD risk. This screening method is particularly interesting to identify patients who could benefit most from early access to personalized therapies.
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Pruebas Genéticas , Glucosilceramidasa/genética , Enfermedad de Parkinson/diagnóstico , Enfermedad de Parkinson/genética , Anciano , Estudios de Cohortes , Femenino , Pruebas Genéticas/economía , Pruebas Genéticas/métodos , Pruebas Genéticas/normas , Humanos , Masculino , Persona de Mediana Edad , Reproducibilidad de los Resultados , Sensibilidad y EspecificidadRESUMEN
Mutations in the gene encoding the mitochondrial carrier protein SLC25A46 are known to cause optic atrophy associated with peripheral neuropathy and congenital pontocerebellar hypoplasia. We found novel biallelic SLC25A46 mutations (p.H137R, p.A401Sfs*17) in a patient with Parkinson's disease and optic atrophy. Screening of six unrelated patients with parkinsonism and optic atrophy allowed us to identify two additional mutations (p.A176V, p.K256R) in a second patient. All identified variants are predicted likely pathogenic and affect very conserved protein residues. These findings suggest for the first time a possible link between Parkinson's Disease and SLC25A46 mutations. Replication in additional studies is needed to conclusively prove this link.
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Proteínas Mitocondriales/genética , Atrofia Óptica/genética , Enfermedad de Parkinson/genética , Proteínas de Transporte de Fosfato/genética , Adulto , Anciano , Femenino , Humanos , Masculino , Mutación , Atrofia Óptica/diagnóstico , Enfermedad de Parkinson/diagnóstico , LinajeRESUMEN
Many human genetic diseases are associated with gross mutations such as aneuploidies, deletions, duplications, or inversions. For these "structural" disorders, conventional gene therapy, based on viral vectors and/or on programmable nuclease-mediated homologous recombination, is still unsatisfactory. To correct such disorders, chromosome transplantation (CT), defined as the perfect substitution of an endogenous defective chromosome with an exogenous normal one, could be applied. CT re-establishes a normal diploid cell, leaving no marker of the procedure, as we have recently shown in mouse pluripotent stem cells. To prove the feasibility of the CT approach in human cells, we used human induced pluripotent stem cells (hiPSCs) reprogrammed from Lesch-Nyhan (LN) disease patients, taking advantage of their mutation in the X-linked HPRT gene, making the LN cells selectable and distinguishable from the resistant corrected normal cells. In this study, we demonstrate, for the first time, that CT is feasible in hiPSCs: the normal exogenous X chromosome was first transferred using an improved chromosome transfer system, and the extra sex chromosome was spontaneously lost. These CT cells were functionally corrected and maintained their pluripotency and differentiation capability. By inactivation of the autologous HPRT gene, CT paves the way to the correction of hiPSCs from several X-linked disorders.
RESUMEN
INTRODUCTION: Neurofascin, encoded by NFASC, is a transmembrane protein that plays an essential role in nervous system development and node of Ranvier function. Anti-Neurofascin autoantibodies cause a specific type of chronic inflammatory demyelinating polyneuropathy (CIDP) often characterized by cerebellar ataxia and tremor. Recently, homozygous NFASC mutations were recently associated with a neurodevelopmental disorder in two families. METHODS: A combined approach of linkage analysis and whole-exome sequencing was performed to find the genetic cause of early-onset cerebellar ataxia and demyelinating neuropathy in two siblings from a consanguineous Italian family. Functional studies were conducted on neurons from induced pluripotent stem cells (iPSCs) generated from the patients. RESULTS: Genetic analysis revealed a homozygous p.V1122E mutation in NFASC. This mutation, affecting a highly conserved hydrophobic transmembrane domain residue, led to significant loss of Neurofascin protein in the iPSC-derived neurons of affected siblings. CONCLUSIONS: The identification of NFASC mutations paves the way for genetic research in the developing field of nodopathies, an emerging pathological entity involving the nodes of Ranvier, which are associated for the first time with a hereditary ataxia syndrome with neuropathy.