Association of a protective paraoxonase 1 (PON1) polymorphism in Parkinson's disease.

Pesticide exposure has been suggested to increase the risk to develop Parkinson's disease (PD). The arylesterase paraoxonase 1 (PON1) is mainly expressed in the liver and hydrolyzes organophosphates such as pesticides. The polymorphism Leu54Met (rs854560) in PON1, impairing enzyme activity and leading to decreased PON1 expression levels, has been reported to be associated with Parkinson's disease (PD). PON1 is part of a cluster on chromosome 7q21.3 together with PON2 and PON3. We investigated the occurrence of four additional polymorphisms in PON1 and two in PON2 in a Swedish PD case-control material. We found a significant association (p=0.007) with a PON1 promoter polymorphism, rs854571. The minor allele was more common among controls than PD cases which suggest a protective effect. This is strengthened by the fact that rs854571 is in strong linkage disequilibrium with another PON1 promoter polymorphism, rs854572, reported to increase PON1 gene expression. Our findings support the hypothesis that PON1 is involved in the etiology of PD and that higher PON1 levels are reducing the risk for PD.

A rare truncating mutation in ADH1C (G78Stop) shows significant association with Parkinson disease in a large international sample.

BACKGROUND: Alcohol dehydrogenases (ADHs) may be involved in the pathogenesis of neurodegenerative disorders because of their multiple roles in detoxification pathways and retinoic acid synthesis. In a previous study, significant association of an ADH class IV allele with Parkinson disease (PD) was found in a Swedish sample. PATIENTS: The previously associated single-nucleotide polymorphism plus 12 further polymorphisms in the ADH cluster on human chromosome 4q23 were screened for association in an extension of the original sample that now included 123 Swedish PD patients and 127 geographically matched control subjects. A rare nonsense single-nucleotide polymorphism in ADH1C (G78stop, rs283413) was identified in 3 of these patients but in no controls. To obtain sufficient power to detect a possible association of this rare variant with disease, we screened a large international sample of 1076 PD patients of European ancestry and 940 matched controls. RESULTS: The previously identified association with an ADH class IV allele remained significant (P<.02) in the extended Swedish study. Furthermore, in the international collaboration, the G78stop mutation in ADH1C was found in 22 (2.0%) of the PD patients but only in 6 controls (0.6%). This association was statistically significant (chi(2)(1) = 7.5; 2-sided P = .007; odds ratio, 3.25 [95% confidence interval, 1.31-8.05]). In addition, the G78stop mutation was identified in 4 (10.0%) of 40 Caucasian index cases with PD with mainly hereditary forms of the disorder. CONCLUSION: Findings presented herein provide further evidence for mutations in genes encoding ADHs as genetic risk factors for PD.

ALDH1 mRNA: presence in human dopamine neurons and decreases in substantia nigra in Parkinson's disease and in the ventral tegmental area in schizophrenia.

Dopamine (DA) neurons degenerate in Parkinson's disease and dopamine neurotransmission may be affected in psychotic states seen in schizophrenia. Understanding the regulation of enzymes involved in DA metabolism may therefore lead to new treatment strategies for these severe conditions. We investigated mRNA expression of the cytosolic aldehyde dehydrogenase (ALDH1), presumably involved in DA degradation, by in situ hybridization in DA neurons of human postmortem material. Parallel labeling for GAPDH, neuron-specific enolase, tyrosine hydroxylase, dopamine transporter, and dopamine beta-hydroxylase was used to ensure suitability of tissue specimen and to identify all dopamine neurons. ALDH1 was found to be expressed highly and specifically in DA cells of both substantia nigra (SN) and the ventral tegmental area (VTA) of controls. A marked reduction of ALDH1 expression was seen in surviving neurons of SN pars compacta but not of those in the VTA in Parkinson's disease. In patients suffering from schizophrenia we found ALDH1 expression at normal levels in DA cells of SN but at significantly reduced levels in those of the VTA. We conclude that ALDH1 is strongly and specifically expressed in human mesencephalic dopamine neurons and that low levels of ALDH1 expression correlate with DA neuron dysfunction in the two investigated human conditions.

Refined mapping of the Welander distal myopathy region on chromosome 2p13 positions the new candidate region telomeric of the DYSF locus.

Welander distal myopathy (WDM) is a late adult-onset autosomal dominant disorder, characterized by a slow progression and distal limb weakness of the extremity muscles. The WDM locus has been mapped to chromosome 2p13. Within this region a common shared haplotype co-segregates in all affected patients, indicating a founder effect. By undertaking an extended linkage analysis we have significantly reduced the WDM locus to a critical interval of approximately 1.2 Mb flanked by markers D2S358 and PAC3-H52. The dysferlin gene, a strong candidate gene responsible for two other distal myopathies in the same region, is located centromeric to PAC3-H52 and can thereby formally be excluded as cause for WDM.

NURR1 promoter polymorphisms: Parkinson's disease, schizophrenia, and personality traits.

We have previously identified mutations in exon three in NURR1 (NR4A2) in two patients with schizophrenia (SZ) and one patient with bipolar disease with psychotic symptoms. In the present study we analyzed the promoter region of NURR1 and identified five polymorphic sites: three were found to be in strong linkage disequilibrium with a previously identified polymorphic site in the sixth intron. One polymorphism of this haplotype and the two other independent polymorphisms were investigated for their possible association with SZ and Parkinson's disease (PD) by comparing their frequencies in a Swedish material consisting of 134 subjects with SZ and 207 matched controls and 108 subjects with PD and 125 matched controls. Exon 1 was also investigated in our Parkinson and control material but no variances were found. The distributions of the two most informative polymorphisms in the promoter were investigated in an American material as well consisting of 141 subjects with SZ and 139 matched controls. Furthermore, the identified markers were screened for association with putative endophenotypes of SZ in the Swedish material. The distribution of sequence variants among the Swedish controls matched for SZ was investigated with regard to personality. No significant genotype or allelic association of the three sequence variants with SZ or PD was found. Several comparisons regarding endophenotypes or personality indicated association at the 5% confidence level, although correction for multiple testing rendered none of these findings significant. We conclude that the identified polymorphic sites in the human NURR1 are unlikely to be involved in conferring susceptibility for SZ or PD in our patient material.

Two NOTCH4 polymorphisms and their relation to schizophrenia susceptibility and different personality traits.

BACKGROUND: Recently, linkage disequilibrium mapping of the major histocompatibility complex region on the short arm of human chromosome 6 suggested that the NOTCH4 locus is highly associated with schizophrenia. OBJECTIVES AND METHODS: We analysed two polymorphisms in this gene in Swedish schizophrenic patients ( =74) and control subjects ( =135). The NOTCH4 variants were also analysed in schizophrenic patients with regard to subdiagnosis, age at first hospitalization, abuse/dependence of alcohol, solvents, or drugs, previous suicide attempts, extrapyramidal symptoms, treatment with anticholinergic drugs, and response to anti-psychotic drug treatment. Control subjects were scrutinized with regard to personality, another partially heritable trait suggested being of importance in schizophrenia. In addition, two intermediate endophenotypes suggested being of importance in schizophrenia, dopamine D(2) receptor density in striatum and monoamine metabolites in cerebrospinal fluid, respectively, were investigated with regard to the two NOTCH4 variants. RESULTS: There was no significant association between the patients and the controls for the two investigated polymorphisms neither for the parameters analysed in the schizophrenia material. The NOTCH4 SNP2 variant, an A-->G substitution, was associated with the Karolinska Scales of Personality Irritability scale. The NOTCH4 (CTG)(n) variant was associated with the revised NEO personality inventory Extraversion and Activity (E4) scales. However, after correction for multiple testing, no difference remained significant. The results for the endophenotypes and the polymorphisms were non-significant. CONCLUSIONS: The present study does not support that the investigated NOTCH4 variants have a major influence on susceptibility to schizophrenia or related neurobiological traits.

CTLA4 dimorphisms and the multiple sclerosis phenotype.

Cytotoxic T lymphocyte-associated antigen-4 (CTLA-4), expressed on activated T cells, binds to B7 molecules on antigen-presenting cells. Signaling via CTLA-4 results in downregulation of ongoing T-cell clonal expansion. A single-nucleotide polymorphism (SNP) in exon 1 of CTLA4 is associated with susceptibility to several autoimmune diseases, including multiple sclerosis (MS). In this two-stage study, we investigated whether haplotypes composed of exon 1-SNP alleles and alleles of a promoter-region SNP influence age at onset, disease severity and disease course in MS. In stage 1, deviations in CTLA4 haplotype frequencies were observed in patients subgrouped by course; in stage 2, none of these original associations were confirmed.

Further evidence for an association of the paraoxonase 1 (PON1) Met-54 allele with Parkinson's disease.

Paraoxonase1 (PON1) is an arylesterase mainly expressed in the liver that hydrolyzes organophosphates such as pesticides, reported risk factors for Parkinson's disease (PD), and other neurotoxins. A Leu-Met 54 polymorphism in the gene for PON1-affecting enzyme activity was recently shown, employing a new restriction enzyme technique, to be associated with Parkinson's disease. We examined the same polymorphism by automated capillary sequencing in a sample of Caucasian subjects from the Stockholm area in Sweden (127 healthy individuals and 114 patients with PD) and found similar distributions and a similar difference in our sample. The genotype distribution in our PD material was LL 36.0%, LM 45.6%, and MM 18.4%; in our control material, it was LL 45.7%, LM 44.1%, and MM 10.2%. Based on the previously established increase in allele frequencies of the lower-activity Met-variant of PON1, we could confirm a significant association using a one-sided chi(2) test. Results remained significant with a two-sided chi(2) test, allowing for both increases and decreases in frequencies. Our data confirm an association between the PON1 Leu-Met 54 polymorphism and PD by demonstrating a similar association. The distribution between familial and nonfamilial PD patients was equal. No other synonymous or nonsynonymous polymorphisms were found in the sequenced coding region of PON1.