Background Leucine-rich repeat kinase 2 (LRRK2) is known to harbor highly penetrant mutations linked to familial parkinsonism. However, its full polymorphic variability in relationship to Parkinson’s disease (PD) risk has not been systematically assessed. Methods We examined the frequency pathogenicity of 121 exonic LRRK2 variants in three ethnic series (Caucasian [N=12,590], Asian [N=2,338] and Arab-Berber [N=612]) consisting of 8,611 patients and 6,929 control subjects from 23 separate sites of the Genetic Epidemiology of Parkinson’s Disease Consortium. Findings Excluding carriers of previously known pathogenic mutations, new independent risk associations were found for polymorphic variants in Caucasian (p.M1646T, OR: 1.43, 95% CI: 1.15 – 1.78, P=0.0012) and Asian (p.A419V, OR: 2.27, 95% CI: 1.35 – 3.83, P=0.0011) populations. In addition, a protective haplotype was observed at >5% frequency (p.N551K-p.R1398H-p.K1423K) in the Caucasian and Asian series’, with a similar finding in the small Arab-Berber series that requires further study (combined 3-series OR: 0.82, 95% CI: 0.72 – 0.94, P=0.0043). Of the two previously reported Asian risk variants p.G2385R was found to be associated with disease (OR: 1.73, 95% CI: 1.20 – 2.49, P=0.0026) but no association was observed for p.R1628P (OR: 0.62, 95% CI: 0.36 – 1.07, P=0.087). Also in the Arab-Berber series, p.Y2189C showed potential evidence of risk association with PD (OR: 4.48, 95% CI: 1.33 – 15.09, P=0.012). Of note, two variants (p.I1371V and p.T2356I) which have been previously proposed as pathogenic were observed in patient and control subjects at the same frequency. Interpretation LRRK2 offers an example where multiple rare and common genetic variants in the same gene have independent effects on disease risk. Lrrk2, and the pathway in which it functions, is important in the etiology and pathogenesis of a greater proportion of patients with PD than previously believed. Funding The present study and original funding for the GEO-PD Consortium was supported by grants from Michael J. Fox Foundation. Studies at individual sites were supported by a number of funding agencies world-wide.
Objective We studied the independent and joint effects of the genes encoding alpha-synuclein (SNCA) and microtubule associated protein tau (MAPT) in Parkinson's disease (PD) as part of a large meta-analysis of individual data from case-control studies participating in the Genetic Epidemiology of Parkinson's Disease (GEO-PD) consortium. Methods Participants of Caucasian ancestry were genotyped for a total of four SNCA (rs2583988, rs181489, rs356219, rs11931074) and two MAPT (rs1052553, rs242557) SNPs. Individual and joint effects of SNCA and MAPT SNPs were investigated using fixed- and random-effects logistic regression models. Interactions were studied both on a multiplicative and an additive scale, and using a case-control and case-only approach. Results Fifteen GEO-PD sites contributed a total of 5302 cases and 4161 controls. All four SNCA SNPs and the MAPT H1-haplotype defining SNP (rs1052553) displayed a highly significant marginal association with PD at the significance level adjusted for multiple comparisons. For SNCA, the strongest associations were observed for SNPs located at the 3′ end of the gene. There was no evidence of statistical interaction between any of the four SNCA SNPs and rs1052553 or rs242557, neither on the multiplicative nor on the additive scale. Interpretation This study confirms the association between PD and both SNCA SNPs and the H1 MAPT haplotype. It shows, based on a variety of approaches, that the joint action of variants in these two loci is consistent with independent effects of the genes without additional interacting effects.
A 68-year-old man presented with a 4-month history of progressive memory loss and mood disorders. Neurologic examination revealed severe impairment of attention and verbal skills, without motor and sensory deficits. His medical history included mild arterial hypertension, idiopathic partial epilepsy, and obsessive compulsive disorder.Brain MRI showed the presence of bilateral, asymmetric, swollen white matter lesions in the cerebral hemispheres, hyperintense in T2-weighted images, that partially involved the left frontal cortex (figure). On diffusion-weighted sequences, the white matter abnormalities were consistent with vasogenic edema. No pathologic contrast enhancement was present.Routine blood tests, inflammatory markers, autoantibodies, neoplastic markers, and paraneoplastic antibodies were within normal limits. CSF examination revealed increased level of proteins (152 mg/dL) and cell count (14 leukocyte/L), without intrathecal synthesis of oligoclonal bands. Bacterioscopic and virologic tests (including HIV and JCV) were negative, both on CSF and serum. Search for tumor or infection by total body CT scan was negative.Stereotactic biopsy of the left frontal white matter lesion showed gliosis without signs of infections or neoplasm.After the biopsy, the patient was treated with dexamethasone 24 mg/day IV for 20 days with marked clinical improvement. A control CSF analysis performed 3 months later was within normal limits (Ͻ1 leukocyte/ L, protein 27 mg/dL). Brain MRI demonstrated a reduction in number and extension of the white matter T2-hyperintense lesions (figure). T2*-weighted gradient echo images showed the presence of multiple microhemorrhages scattered over the entire cerebral cortex. No microbleeds were present in basal ganglia, thalami, and posterior fossa (figure).Diagnosis of probable cerebral amyloid angiopathy-related inflammation (CAA-ri) was made upon clinical and MRI findings, supported by the demonstration of APOE ⑀4 homozygosity.A search for A deposits in brain tissue and vessel walls on the biopsy sample was negative; a possible explanation is the deep white matter target, with absence of cortex and leptomeninges in the specimen. The A 1-42 protein in the CSF was reduced both in the first (129 pg/mL) and second (125 pg/mL) lumbar puncture compared to normal values (682-1,063 pg/mL). The A 1-40 protein was also investigated (457 pg/mL in the first CSF; 238 pg/mL in the second); however, due to the large variability of this assay as reported in literature, the meaning of these values is unclear.We hypothesized a spontaneous autoimmune process against CNS A proteins, and assessed the levels of anti-A 1-40 and 1-42 autoantibodies in our patient's CSF, both before and after steroid treatment, compared to 6 age-matched controls (mean age: 63 Ϯ 19 years) and 4 patients with MS (mean age: 45 Ϯ 17 years). We used our ELISA, as described, 1 and detected a marked increase of anti-A 1-40 and 1-42 autoantibodies in the CSF of our CAA-ri patient obtained prior to treatment compared to controls and ...
Our findings suggest that SNCA REP1 genotype and herbicides have independent effects on risk of Parkinson disease, primarily in younger subjects.
Generation of reactive oxygen species during dopamine (DA) oxidation could be one of the factors leading to the selective loss of nigral dopaminergic neurons in Parkinson’s disease (PD). Vesicular monoamine transporter type 2 (VMAT2) proteins in nerve terminals uptake dopamine into synaptic vesicles, preventing its cytoplasmic accumulation and toxic damage to nigral neurons. Polymorphisms in VMAT2 gene and in its regulatory regions might therefore serve as genetic risk factors for PD. In the present study, we have analyzed 8 single-nucleotide polymorphisms (SNPs) located within/around the VMAT2 gene for association with PD in an Italian cohort composed of 704 PD patients and 678 healthy controls. Among the 8 SNPs studied, only the 2 located within the promoter region (rs363371 and rs363324) were significantly associated with PD. In the dominant model, odds ratios were 0.72 (95% confidence interval [CI]: 0.6–0.9, p < 0.005) for rs363371 and 0.76 (95% CI: 0.6–0.9, p = 0.01) for rs363324; in the additive model, odds ratios were 0.78 (95% CI: 0.65–0.94, p = 0.008) for rs363371 and 0.85 (95% CI: 0.7–20.92, p = 0.04) for rs363324. There were no significant relationships between the remaining SNPs (rs363333, rs363399, rs363387, rs363343, rs4752045, and rs363236) and the risk of sporadic PD in any genetic model. This study adds to the previous evidence suggesting that variability in VMAT2 promoter region may confer a reduced risk of developing PD, presumably via mechanisms of gene overexpression.
Objectives:The objective of this study is to clarify the role of (G4C2)n expansions in the etiology of Parkinson disease (PD) in the worldwide multicenter Genetic Epidemiology of Parkinson's Disease (GEO-PD) cohort.Methods:C9orf72 (G4C2)n repeats were assessed in a GEO-PD cohort of 7,494 patients diagnosed with PD and 5,886 neurologically healthy control individuals ascertained in Europe, Asia, North America, and Australia.Results:A pathogenic (G4C2)n>60 expansion was detected in only 4 patients with PD (4/7,232; 0.055%), all with a positive family history of neurodegenerative dementia, amyotrophic lateral sclerosis, or atypical parkinsonism, while no carriers were detected with typical sporadic or familial PD. Meta-analysis revealed a small increase in risk of PD with an increasing number of (G4C2)n repeats; however, we could not detect a robust association between the C9orf72 (G4C2)n repeat and PD, and the population attributable risk was low.Conclusions:Together, these findings indicate that expansions in C9orf72 do not have a major role in the pathogenesis of PD. Testing for C9orf72 repeat expansions should only be considered in patients with PD who have overt symptoms of frontotemporal lobar degeneration/amyotrophic lateral sclerosis or apparent family history of neurodegenerative dementia or motor neuron disease.
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