Search

Background: Neurological disorders are a highly heterogeneous group of pathological conditions that affect both the peripheral and the central nervous system. These pathologies are characterized by a complex and multifactorial etiology involving numerous environmental agents and genetic susceptibility factors. For this reason, the investigation of their pathogenetic basis by means of traditional methodological approaches is rather arduous. High-throughput genotyping technologies, including the microarray-based comparative genomic hybridization (aCGH), are currently replacing classical detection methods, providing powerful molecular tools to identify genomic unbalanced structural rearrangements and explore their role in the pathogenesis of many complex human diseases. Methods: In this report, we comprehensively describe the design method, the procedures, validation, and implementation of an exon-centric customized aCGH (NeuroArray 1.0), tailored to detect both single and multi-exon deletions or duplications in a large set of multi- and monogenic neurological diseases. This focused platform enables a targeted measurement of structural imbalances across the human genome, targeting the clinically relevant genes at exon-level resolution. Conclusion: An increasing use of the NeuroArray platform may offer new insights in investigating potential overlapping gene signatures among neurological conditions and defining genotype-phenotype relationships.

Alzheimer's disease (AD) is a devastating disease mainly afflicting elderly people, characterized by decreased cognition, loss of memory, and eventually death. Although risk and deterministic genes are known, major genetics research programs are underway to gain further insights into the inheritance of AD. In the last years, in particular, new developments in genome-wide scanning methodologies have enabled the association of a number of previously uncharacterized copy number variants (CNVs, gain or loss of DNA) in AD. Because of the exceedingly large number of studies performed, it has become difficult for geneticists as well as clinicians to systematically follow, evaluate, and interpret the growing number of (sometime conflicting) CNVs implicated in AD. In this review, after a brief introduction of this type of structural variation, and a description of available databases, computational analyses, and technologies involved, we provide a systematic review of all published data showing statistical and scientific significance of pathogenic CNVs and discuss the role they might play in AD.

γ-Secretase proteins complex cleaves the amyloid precursor protein (APP) to generate amyloid-β (Aβ) peptides. Considerable evidence suggests that alterations in genes encoding these proteins exert their influence on the pathogenesis of familial Alzheimer's disease (FAD). Presenilin enhancer-2 gene ( PEN-2 ) is a necessary component of the γ-Secretase complex. Recently, it has been shown that PEN-2 mutations could be involved in Alzheimer's disease (AD). We performed a mutational screening of all PEN-2 coding and promoter regions in a FAD cohort derived from Southern Italy. Four hundred and fifty-two subjects (FAD: 97; Controls: 355) were recruited for this study. We identified for the first time in a key region necessary for the promoter activity a novel 3 bp deletion in a subject with early-FAD. Our genetic data demonstrate that the mutant allele may influence the transcriptional activity of the PEN-2 gene. Although the effective role of the PEN-2 promoter deletion in AD is not entirely clear, these findings might lead to more studies on its functional and genetic role.

Estrogen receptor 1 gene polymorphisms (ESR1) have been found to be associated with multiple sclerosis (MS) in both Japanese and Finnish populations. We investigated the association between ESR1 polymorphisms (PvuII and XbaI) and MS in a study of 132 MS patients and 129 controls from the same geographic background (southern Italy). Allelic and genotypic frequencies were not different between MS patients and population controls for either the PvuII or XbaI polymorphism. This result suggests that the association between a given disease and a genomic characteristic must be confirmed by separate investigations in different populations. © 2002 Elsevier Science Ireland Ltd. All rights reserved.

Increasing evidence links dysregulation of NR2B-containing N-methyl-d-aspartate receptor remodelling and trafficking to Alzheimer's disease (AD). This theme offers the possibility that the GRIN2B gene, encoding this selective NR2B subunit, represents a potential molecular modulating factor for this disease. Based on this hypothesis, we carried out a mutation scanning of exons and flanking regions of GRIN2B in a well-characterized cohort of AD patients, recruited from Southern Italy. A "de novo" p.K1293R mutation, affecting a highly conserved residue of the protein in the C-terminal domain, was observed for the first time in a woman with familial AD, as the only genetic alteration of relevance. Moreover, an association study between the other detected sequence variants and AD was performed. In particular, the study was focused on five identified single nucleotide polymorphisms: rs7301328, rs1805482, rs3026160, rs1806191 and rs1806201, highlighting a significant contribution from the GRIN2B rs1806201 T allele towards disease susceptibility [adjusted odds ratio (OR) = 1.92, 95% confidence interval (CI) 1.40-2.63, p < 0.001, after correction for sex, age, and APOE epsilon 4 genotype]. This was confirmed by haplotype analysis that identified a specific haplotype, carrying the rs1806201 T allele (CCCTC), over-represented in patients versus controls (adjusted OR = 6.03; p < 0.0001). Although the pathogenic role of the GRIN2B-K1293R mutation in AD is not clear, our data advocate that genetic variability in the GRIN2B gene, involved in synaptic functioning, might provide valuable insights into disease pathogenesis, continuing to attract significant attention in biomedical research on its genetic and functional role.

A 35-year-old young man displayed Leber’s optic neuropathy (LHON) due to T14484C and multiple sclerosis (MS) phenotype that was dominated by symptoms and signs of spinal cord impairment. Magnetic resonance imaging (MRI) revealed demyelinating lesions extending from D6 to D11 in the spinal cord with gadolinium enhancement, while only three linear demyelinating lesions were seen on brain MRI. In the literature, a major involvement of the spinal cord was already reported in three of four male patients with the 14484 LHON mutation who developed MS, but the reasons of this peculiar association remain unknown, and further research in this area is needed.

To investigate the role of the matrix metalloproteinase-9 gene (MMP-9) in multiple sclerosis (MS), we analyzed the functional -1562C/T and -90 (CA)n repeat polymorphisms, located in the promoter region of this gene, in 243 Italian patients with MS and 173 healthy controls. A markedly significant increase of the -1562T allele carriers was found in patients with MS compared to controls (P = 5.6 x 10-5, adjusted OR = 2.57, 95% CI = 1.52- 4.36). Moreover, carriers of (CA)>20 repeats were also significantly more frequent among patients with MS than among controls (P = 0.011, adjusted OR = 1.53, 95% CI = 1.06-2.02). There were no differences in MS disability status, age at onset or disease duration among the genotypes. Haplotype analysis showed that the haplotype formed by the -1562T allele and the L allele ((CA)d20) was over-represented in patients with MS versus controls, suggesting this haplotype could be a possible risk factor for development of the disease (P = 2.14 x 10-5, OR=6.79, 95% CI=2.82-16.35). These results suggest that genetic polymorphisms of the MMP-9 promoter regions may influence the susceptibility to MS.

Caspase-9 is a primary effector CASP that executes programmed cell death, which plays an important role in the development of multiple sclerosis (MS). Polymorphisms in the CASP-9 gene may influence its activity, thereby modulating the susceptibility to MS. To test this hypothesis, we evaluated a SNP in the CASP-9 gene in a set of Italian patients from Southern Italy and healthy control subjects. Our results suggest that the presence of the G/G genotype represents a higher risk factor in our MS population and a differential production of CASP-9 might be a contributory factor in determining the severity of MS.

Autosomal Dominant Optic Atrophy (ADOA or Kier's disease) is one of the most frequent forms of inherited optic atrophy, often presenting in the first decade of life with progressive impairment of visual acuity, variably combined with dyschromatopsia and optic nerve pallor. More than 90 mutations spanning throughout the Optic Atrophy 1 (OPA1) gene were disease-associated with most cases of ADOA. Genotype-phenotype comparisons have been inconclusive except for ADOA complicated with a rare sensorineural deafness (ADOAD). Here we present a family with an unusual phenotype of ADOAD and peripheral polineuropathy associated with a novel OPA1 mutation.

Several pathogenetic factors seem to contribute to the development of Alzheimer's disease (AD). Some data point to a role for traumatic brain injury (TBI), but this suggestion is not universally supported. Mayeux et al. have shown that TBI increases the risk of AD, but only through a synergistic relationship with apolipoprotein epsilon (Apo E) 4. We present the results of a cross-sectional and longitudinal study of the relationship between these factors, conducted in northern and southern Italy. We studied 337 consecutive patients with probable AD and 63 subjects with mild cognitive impairment (MCI). Information concerning head injuries was collected by interview of informants and review of medical records. Twenty-one patients with AD and 9 with MCI were found to have a history of TBI with loss of consciousness. AD and MCI patients with a history of TBI, compared with control groups matched for age, sex, education and degree of mental impairment, showed more marked depressive and behavioural disturbances (Global Deterioration Scale and Neuropsychiatric Inventory, p0.05). Six- and 12-month follow up of both groups did not show significant differences in the rate of progression of cognitive changes. A high frequency of Apo E 4 was detected in the patients with TBI and cognitive impairment (40.5% in the AD and 11% in the MCI subgroups). The distribution of the epsilon 4 allele in our control group was 4%, comparable to that found in the Italian population. Distribution of the above parameters was similar in patients from northern and southern Italy. The higher frequency of TBI and Apo E 4 genotype among AD and MCI patients confirms the synergistic interaction of environmental and genetic factors in the development of dementia. Our data do not suggest that the presence of these two factors influences the clinical presentation or the course of the disease.

Lymphocyte and monocyte brain infiltration determines inflammation in multiple sclerosis. The trafficking of these cells into the CNS results from the VLA-4 binding with its ligand on brain endothelial cells. MS patients treated with an antibody against the alpha-4 subunit, which inhibits this interaction, prevents brain lesion development. We investigated the association between VLA-4 gene polymorphisms and MS in a study on 275 patients and 255 controls. No differences were detected, thus suggesting that these polymorphisms are not a significant genetic risk factor for susceptibility to MS in Italy.

Specific variations in the prion protein gene (PRNP) are associated with, and prevalent in patients with intractable temporal lobe epilepsy (TLE) and influence the surgical outcome. We investigated whether or not the PRNP gene is a susceptibility gene in temporal lobe epileptic patients with mild epilepsy. We systematically screened the entire open reading frame of the PRNP gene and evaluated the genetic contribution of the functional PRNP M129V polymorphism in 289 patients with mild TLE compared with a neurologically unaffected age and sex matched control group (n = 272). Statistical analysis revealed a moderate difference in the distribution at codon 129 of the PRNP gene between sporadic mild TLE patients and healthy controls (p = 0.036; OR= 1.30; 95% CI = 1.01–1.68). Although, there was no statistically significant difference in the genotype distribution within the study groups (p = 0.101), a further analysis showed that the 129V allele was highly represented only in women with TLE compared with control group (p = 0.006, OR= 1.632; 95%CI = 1.15–2.31). This is the first publication of data that support the hypothesis that the common methionine/valine polymorphism at codon 129 of the PRNP gene may modify the susceptibility of women to mild TLE.

Tumor Necrosis Factor Receptor Super Family 6 gene (TNFRSF6), also known as FAS, encodes the Fas antigen, a cell surface receptor mediating cell apoptosis, situated on chromosome 10q located near the region of linkage to sporadic Alzheimer’s disease (sAD). FAS levels have been reported elevated in the brain of AD patients. Due to both positional and pathobiological criteria, the association of the FAS antigen with this pathology is of great interest. We have tested two SNPs in the FAS gene in 223 Italian patients with non-familial AD from Southern Italy (Calabria region) and 211 healthy control subjects. No significant differences in allelic and genotypic distributions were found between cases and controls, or late and early-onset AD patients, thus suggesting that these polymorphisms do not represent an AD risk factor in our population.

Specific variations in the prion protein gene (PRNP) are associated with, and prevalent in patients with intractable temporal lobe epilepsy (TLE) and influence the surgical outcome. We investigated whether or not the PRNP gene is a susceptibility gene in temporal lobe epileptic patients with mild epilepsy. We systematically screened the entire open reading frame of the PRNP gene and evaluated the genetic contribution of the functional PRNP M129V polymorphism in 289 patients with mild TLE compared with a neurologically unaffected age and sex matched control group ( n = 272). Statistical analysis revealed a moderate difference in the distribution at codon 129 of the PRNP gene between sporadic mild TLE patients and healthy controls ( p = 0.036; OR = 1.30; 95% CI = 1.01–1.68). Although, there was no statistically significant difference in the genotype distribution within the study groups ( p = 0.101), a further analysis showed that the 129V allele was highly represented only in women with TLE compared with control group ( p = 0.006, OR = 1.632; 95%CI = 1.15–2.31). This is the first publication of data that support the hypothesis that the common methionine/valine polymorphism at codon 129 of the PRNP gene may modify the susceptibility of women to mild TLE.

Multiple sclerosis (MS) is a common, heterogeneous disorder of the central nervous system with a complex trait composed of both genetic and environmental factors. Recently, scientific interest has increased in defining factors that possibly contribute to brain functional plasticity; the results might be useful to assess the relationship between MS lesion burden and clinical events, as well as explaining the well-known phenotypic heterogeneity of the disease. In this study, we explored the effect of the Val66Met brain-derived neurotrophic factor (BDNF) functional polymorphism on cognitive performances and volumetric measurements obtained by magnetic resonance imaging of the brain in a selected population of relapsing–remitting MS (RRMS) patients, with relatively short disease duration and minimal clinical disability, compared to gender, age and educational-level matched healthy subjects. We found that in the RRMS group, the BDNF Met-allele was significantly associated with the lower volume of cerebral grey matter (GM) (P = 0.005). Furthermore, a significant (P = 0.013) interaction effect between ‘MS-status’ and the BDNF genotype was found for GM volumes, with the result that patients carrying the BDNF Met-allele showed a higher risk of developing global GM atrophy than the homozygous Val/Val. No BDNF-related impact on global neuropsychological functions resulted in either RRMS patients or controls. Our data seem to be consistent with the reported influence of BDNF in neuronal plasticity, thus suggesting that the Met-allele might have a negative prognostic effect on cortical morphometry in RRMS patients.

Background: Previous studies have examined the role of APOE variation in multiple sclerosis (MS), but have lacked the statistical power to detect modest genetic influences on risk and disease severity. The meta- and pooled analyses presented here utilize the largest collection, to date, of MS cases, controls, and families genotyped for the APOE epsilon polymorphism. Methods: Studies of MS and APOE were identified by searches of PubMed, Biosis, Web of Science, Cochrane Review, and Embase. When possible, authors were contacted for individual genotype data. Meta-analyses of MS case-control data and family-based analyses were performed to assess the association of APOE epsilon genotype with disease risk. Pooled analyses of MS cases were also performed to assess the influence of APOE epsilon genotype on disease severity. Results: A total of 22 studies (3,299 MS cases and 2,532 controls) were available for meta-analysis. No effect of e2 or e4 status on MS risk was observed (summary OR 1.14, 95% CI 0.96–1.34 and OR 0.89, 95% CI 0.78–1.01). Results obtained from analyses of APOE genotypes in 1,279 MS families were also negative ( p = 0.61). Finally, results from pooled analyses of 4,048 MS cases also argue strongly that APOE epsilon status does not distinguish a relapsing-remitting from primary progressive disease course, or influence disease severity, as measured by the Expanded Disability Status Scale and disease duration. Conclusion: Overall, these findings do not support a role for APOE in multiple sclerosis, and underscore the importance of using large sample sizes to detect modest genetic effects, particularly in studies of genotype-phenotype relationships.

There is evidence that multiple sclerosis (MS) may associated with cognitive impairment in 25 to 40% of cases. The gene encoding myeloperoxidase (MPO) is involved in molecular pathways leading to β-amyloid deposition. We investigated a functional biallelic (G/A) polymorphism in the promoter region (-463) of the MPO gene in 465 patients affected by MS, divided into 204 cognitively normal and 261 impaired. We did not find significant differences in allele or genotype distributions between impaired and preserved MS patients. Our findings suggest that MPO polymorphism is not a risk factor for cognitive impairment in MS.

Purpose To clarify the possible role of other factors including the ApoE epsilon4 allele for memory decline in temporal lobe epilepsy (TLE). Methods We conducted a neuropsychological and molecular study in 138 consecutive patients (78 female patients; mean age, 50.2 years, SD +/- 17.9; range, 14 to 87 years) with mild nonlesional TLE, who rarely or never had seizures at long-term follow-up. The mean age at seizure onset was 33.0 years (SD, +/-21.7), and the mean duration of epilepsy was 17.1 years (SD, +/-15.7). Results Thirty-four (25%) of 138 patients had test scores indicating verbal learning deficit (VLD). The presence of an ApoE epsilon4 allele was associated with an increased risk of VLD (OR, 4.18; 95% CI, 1.66-10.55). The effect of the ApoE genotype was independent of both the age at epilepsy onset and disease duration as well as of a low educational level, which were separately associated with VLD (p values = 0.045, 0.001, and 0.001, respectively). A significant linear trend (p = 0.005) was seen in the relation between disease duration and cognitive impairment, with the highest risk being in patients with an epilepsy duration > or =25.5 years (OR, 7.06; 95% CI, 1.67-29.85), especially if they carried the epsilon4 allele (OR, 32.29; 95% CI, 5.23-195.72). Conclusions These results provide evidence for an alteration in cognitive performance as a function of the presence of the ApoE epsilon4 allele and point to the critical role of disease duration itself for cognitive impairment in TLE.

Background: The genes encoding myeloperoxiclase (MPO) and alpha(2),-macroglobulin (A2M) are involved in molecular pathways leading to beta-amyloid deposition. Two polymorphic sites in these genes (MPO-G/A and A2M-Ile/Val) have been associated with Alzheimer disease (AD), but conflicting findings have been reported in populations with different ethnic backgrounds. Objectives: To study the association of MPO-G/A and A2M-Ile/Val polymorphisms, with sporadic AD and to investigate the interactions among the MPO, A2M, and apolipoprotein E (APOE) gene polymorphisms in determining the risk of the development of AD. Design: Case-control study. Setting: Referral center for AD in Calabria, southern Italy Participants: One hundred forty-eight patients with sporadic AD and 158 healthy control subjects. Results: The MPO-G and A2M-Val alleles were found more frequently in cases than in controls, as were the MPO-G/G and A2M-Val/Val genotypes. The odds ratio (OR) for the MPO-G/G genotype was 1.78 (95% confidence interval [CI], 1.13-2.80); for the A2M-Val/Val genotype, 3.81 (95% Cl, 1.66-8.75). The presence of MPO-G/G and A2M-Val/Val genotypes synergistically increased the risk of AD (OR, 25.5; 95% Cl, 4.65-139.75). Stratification of cases by sex, age at onset of AD, and APOE-epsilon4 status did not show significant differences in the distribution of MPO or A2M polymorphisms. Conclusions: The MPO and A2M polymorphisms are associated with sporadic AD in southern Italy. Moreover, a genomic interaction between these polymorphisms increases the risk of the development of AD.

BACKGROUND: Cognitive impairment may occur at any time during the course of multiple sclerosis (MS), and it is often a major cause of disability in patients with the disease. The APOE-epsilon4 allele is the major known genetic risk factor for late onset familial and sporadic Alzheimer's Disease (AD), and it seems to be implicated in cognitive decline in normal elderly persons. OBJECTIVE: To investigate the clinical and genetic variables that can be associated with the cognitive decline in patients with MS. METHODS: Five-hundred and three patients with clinically definite MS underwent a battery of neuropsychological tests and, according to the number of failed tests, were divided into cognitively normal and impaired. All patients were genotyped for APOE gene polymorphisms. RESULTS: Fifty-six percent of MS patients showed, to different extents, cognitive impairment. Cognitive decline was predominant in men and was associated with disease duration, Kurtzke Expanded Disability Status Scale (EDSS) score, a low level of education, and, interestingly, the epsilon4 allele of the APOE gene. By contrast, cognitive impairment in women was independent of any investigated variable. CONCLUSION: The findings demonstrate that clinical and genetic factors play a role in men affected by MS developing cognitive impairment.

OBJECTIVE: To investigate the association between apolipoprotein E (APOE) polymorphisms and the progression of MS. METHODS: We investigated 428 subjects affected by clinically defined MS, with a disease duration of at least three years. We collected data concerning the age at onset of MS, clinical type, disease duration and disability according to the expanded disability status scale (EDSS). We also calculated the progression index (PI) to evaluate disease progression. APOE genotyping and the -491 A/T polymorphism of the APOE promoter were determined. RESULTS: No association was observed between the APOE epsilon4 allele and clinical characteristics of our study population. We also investigated the -491 A/T APOE promoter polymorphism in 236 MS subjects and did not find any association between the -491 A/T polymorphism and the selected clinical variables. CONCLUSIONS: In our population the APOE epsilon4 allele and the -491 A/T APOE promoter polymorphism are not associated with a more rapid course of MS.

Although multiple sclerosis (MS) is considered to be an inflammatory demyelinating disease, increasing evidence indicates that it is also an axonal pathology; indeed, studies of experimental allergic encephalitis showed that several neuronal proteins such as synapsins take part in the pathogenesis of the axonal dysfunction. Synapsins are a family of abundant neuron-specific phosphoproteins with crucial roles in synaptogenesis and neuronal plasticity. Distinct genes encode the three different isolated proteins (I, II and III); of interest, the gene of synapsin III (SYN3) is located in the chromosome 22q12-q13, a locus close to one of the candidate susceptibility regions (22q13.1) for MS. In the present study we selected two polymorphisms (g.-631C > G and g.-196A > G) within the SYN3 5?-promoter region because of the protein's role and genetic location; we analysed the allele and genotype distributions of these polymorphisms in a selected MS population of southern Italy. An inverse association between MS and the g-631C > G polymorphism was found; indeed, the two polymorphisms were in almost complete linkage disequilibrium and the haplotype analysis showed that the C631/A196 haplotype seemed to confer a significant protection against MS.

Background: Dysfunction of γ-aminobutyric acid (GABA) (B) receptors has been implicated in the pathogenesis of temporal lobe epilepsy (TLE).Objective: To evaluate the genetic contribution of cloned human GABA(B) receptors to TLE.Methods: The authors genotyped 141 patients (78 women and 63 men; mean age = 49.1 ± 18.0 years) with nonlesional TLE and 372 age- and sex-matched normal individuals for the known polymorphism G1465A in the human GABA(B) receptor 1 [GABA(B[1])] gene.Results: There was a highly significant overrepresentation of the G1465A heterozygote in patients with TLE compared with controls. The A/G genotype was found in 17% of the 141 patients with TLE and in only 0.5% of the 372 controls (p < 0.0001). The authors also found that patients carrying the A allele had a significantly higher risk (p = 0.003, OR = 6.47, 95% CI = 2.02 to 20.76) of developing drug-resistant TLE. Furthermore, the age at onset of seizures tended to be lower in patients with A/G genotype, but the difference was not significant.Conclusions: The results of this study indicate that the GABA(B[1]) polymorphism (G1465A) confers a highly increased susceptibility to TLE. Moreover, it seems to influence the severity of this common epileptic disorder.

The authors investigated the segregation of two polymorphisms of the alpha2-macroglobulin gene (A2M-I/D and A2M-Ile1000Val) in patients with sporadic AD from southern Italy. The A2M-I and A2M-Val1000 alleles were more frequent in cases than in controls, and this effect was independent from the APOE-epsilon4 status as well as from the age at onset of AD. Moreover, subjects carrying the A2M genotype I/I-Val/Val had a threefold increase of risk for AD. These data support a population-based susceptibility for AD linked to A2M polymorphisms.

ND1-ND6 are seven subunits of the NADH CoQ reductase or complex I of the respiratory chain. They are encoded by mitochondrial DNA and involved in the oxidative phosphorylation (OXPHOS) pathway. We observed a new genetic polymorphism in human mitochondrial DNA (mtDNA) caused by a variation of the base pair (bp) at position 14562, which is located in the gene for mitochondrial ND6 (Anderson et al.1981). The variant is a C-->NT transition which creates one new restriction site: Mbo I, leading to Valine substitution for Isoleucine. This polymorphism was observed in a patient, during a screening study for primary LHON mutations with multiple sclerosis (Kellar-Wood et al. 1994). The molecular analysis of other asymptomatic members of proband's family confirmed the same nucleotide variation. The primary LHON mutations at nucleotides 11778, 3460 and 14484 (Howell et al. 1995) were not present in this patient. We performed a mutational analysis in fifty normal subjects from the same geographic background, but this polymorphism was not detected. Thus, this novel nucleotide transition is a neutral polymorphism.

A 64-year-old woman, who had no personal or family history of neurologic diseases, had an 18-month history of epilepsia partialis continua (EPC) associated with a moderate intellectual deterioration and subtle extrapyramidal rigidity. There was no photosensitive response. A thorough laboratory investigation was unremarkable. A biopsy of the rectal mucosa revealed abundant fingerprint profiles diagnostic of Kufs' disease (KD). Our case expands the clinical picture of KD and suggests that such a diagnosis should be considered in adult-onset EPC.

Objective: To investigate whether polymorphisms in the genes for dopamine receptors D 1 and D 2 are associated with the risk of developing peak-dose dyskinesias in PD. Background: Peak-dose dyskinesias are the most common side effects of levodopa therapy for PD. The identified predictors may only partially account for the risk of developing peak-dose dyskinesias because a substantial proportion of patients never develop peak-dose dyskinesias. Genetic factors could play a role in determining the occurrence of peak-dose dyskinesias. Methods: A case-control study of 136 subjects with sporadic PD and 224 population control subjects. We studied three polymorphisms involving the dopamine receptor D 1 gene and one intronic short tandem repeat polymorphism of the dopamine receptor D 2 gene. Results: The polymorphisms of the dopamine receptor D 1 gene were not associated with the risk of developing PD or peak-dose dyskinesias. The 15 allele of the polymorphism of the dopamine receptor D 2 gene was more frequent in parkinsonian subjects than in control subjects. More important, the frequency of both the 13 allele and the 14 allele of the dopamine receptor D 2 gene polymorphism was higher in nondyskinetic than in the dyskinetic PD subjects. The risk reduction of developing peak-dose dyskinesias for PD subjects carrying at least 1 of the 13 or 14 alleles was 72% with respect to the PD subjects who did not carry these alleles. Conclusions: Certain alleles of the short tandem repeat polymorphism of the dopamine receptor D 2 gene reduce the risk of developing peak-dose dyskinesias and could contribute to varying susceptibility to develop peak-dose dyskinesias during levodopa therapy.

Objectives - The APOE gene polymorphism and the -491 A/T polymorphism in its regulatory region have been associated with an increased risk for developing Alzheimer's disease. We examined these polymorphisms in multiple sclerosis (MS) patients, to determine if a genetic predisposition may explain the risk for developing cognitive decline in MS. Material and methods - Eighty-nine relapsing-remitting and secondary progressive MS patients underwent to a full neuropsychological battery as well as to determination of APOE and -491 A/T polymorphisms. Genetic analysis was also performed in 107 population controls. Results - The APOE polymorphism was not associated with the risk of cognitive impairment in MS patients. The AA genotype of the -491 A/T polymorphism in the APOE regulatory region was more frequent in cognitively impaired than in cognitively preserved MS subjects. Conclusion - The AA homozygous state of the -491 A/T polymorphism of the APOE regulatory region is associated with cognitive impairment in patients with MS.