ABSTRACT
Some studies have suggested an overlap of clinical and genetic findings between essential tremor (ET) and Parkinson's disease (PD). The first genome-wide association study in ET showed a significant association with the rs9652490 SNP of the leucine-rich repeat and Ig domain containing 1 (LINGO1) gene. Since patients with PD have higher LINGO1 expression levels compared to healthy controls, and animal models of PD show elevated LINGO1 protein levels after experimentally induced damage in the striatum, it can be inferred that LINGO1 is probably involved in PD pathophysiology. In this study, we performed a genetic association analysis of the rs9652490 and rs11856808 SNPs in Italian PD patients and controls to assess the role of these variants in our population. A total of 567 patients with PD and 468 control subjects were enrolled in five Movement Disorder centers located in Central-Southern Italy. Both variants were significantly associated with PD under a recessive model of inheritance before applying the Bonferroni correction. The GG genotype of rs9652490 and the TT genotype of rs11856808 were less frequent in patients than in controls, suggesting a protective effect against the disease. However, after stringent correction, only the P-values obtained from allele and genotype comparisons of the rs11856808 SNP remained significant. Our findings suggest that LINGO1 plays a certain role in the development of PD in the Italian population and represents an interesting candidate gene responsible for PD, due to its involvement in neurological processes.
Subject(s)
Genome-Wide Association Study/methods , Membrane Proteins/genetics , Nerve Tissue Proteins/genetics , Parkinson Disease/genetics , Aged , Cohort Studies , Female , Humans , Italy/epidemiology , Italy/ethnology , Male , Middle Aged , Parkinson Disease/epidemiology , Parkinson Disease/ethnology , Polymorphism, Single Nucleotide/geneticsABSTRACT
Mutations in the gene DJ-1 have been shown to be a rare cause of early-onset Parkinson's disease (EOPD). Since DJ-1 mutations have been found in patients with Parkinson's disease (PD) from southern Italy, we aimed to investigate whether polymorphisms within the DJ-1 gene could represent a risk factor for sporadic PD. First, we genotyped 294 patients with PD and 298 controls coming from southern Italy to assess the distribution of the insertion/deletion (Ins/Del) polymorphism. In a second phase, we identified five single-nucleotide polymorphisms (SNPs) useful to delimit a region potentially involved and genotyped all patients and controls for these markers. All the markers analyzed were significantly associated with PD at both allelic and genotypic level. The most significant association with the disease was found at the Ins/Del polymorphism (p = 0.0001; adjusted odds ratio (OR ) = 2.05; confidence interval (CI ) = 1.36-3.08). When we considered a three-marker sliding window, we found a highly significant association between the disease and the haplotypes including markers rs17523802, Ins/Del, and rs3766606 (p = 0.0007) and markers Ins/Del, rs3766606 and rs7517357 (p = 0.0054). Our results indicate that polymorphisms located in a region spanning 3535 bp from the promoter to the intron 2 of the DJ-1 gene confer risk to sporadic PD in southern Italy.
Subject(s)
Genetic Predisposition to Disease , Intracellular Signaling Peptides and Proteins/genetics , Oncogene Proteins/genetics , Parkinson Disease/genetics , Polymorphism, Genetic , Adult , Aged , Aged, 80 and over , Female , Genetic Markers , Genotype , Humans , Italy , Male , Middle Aged , Protein Deglycase DJ-1 , Risk FactorsSubject(s)
Epilepsies, Myoclonic/genetics , Mutation , Nerve Tissue Proteins/genetics , Nucleotides/genetics , Sodium Channels/genetics , Base Sequence , Case-Control Studies , Codon , DNA Mutational Analysis , Gene Deletion , Humans , Infant, Newborn , Introns , Italy , Molecular Sequence Data , NAV1.1 Voltage-Gated Sodium ChannelABSTRACT
Dementia is a common complication of Parkinson's disease (PD). It correlates significantly with the presence of cortical, limbic or nigral Lewy bodies, mainly constituted of alpha-synuclein. Mutations of the alpha-synuclein gene (SNCA) have been linked to rare familial forms of PD, while association studies on the promoter polymorphisms have given conflicting results in sporadic patients. We have performed a case control study to investigate whether genetic variability in the promoter of the alpha-synuclein gene could predispose to dementia in PD. A total of 114 demented patients and 114 non-demented patients with sporadic PD were included in the study. Six polymorphic loci (including the Rep1 microsatellite) in the promoter of the SNCA gene were examined. Each marker, taken individually, did not show association to dementia and no significant differences were observed in the inferred haplotype frequencies of demented and non-demented patients. Our data suggest the lack of involvement of the SNCA promoter in the pathogenesis of dementia in PD. Further studies in other populations are needed to confirm these results.
