Andrea Carmine

LRRK2 expression linked to dopamine-innervated areas

Leucine‐rich repeat kinase 2 (LRRK2) has been linked to Parkinsons disease. Our study explores the expression of LRRK2 in human and rodent brain tissue.

NURR1 Mutations in cases of schizophrenia and manic-depressive disorder

Transgenic mice lacking the nuclear orphan transcription factor Nur-related receptor 1 (Nurr1) fail to develop mesencephalic dopamine neurons. There is a highly homologous NURR1 gene in humans (formerly known as NOT) which therefore constitutes a good candidate gene for neurologic and psychiatric disorders with an involvement of the dopamine neuron system, such as Parkinsons disease, schizophrenia, and manic-depression. By direct sequencing of genomic DNA, we found two different missense mutations in the third exon of NURR1 in two schizophrenic patients and another missense mutation in the same exon in an individual with manic-depressive disorder. All three mutations caused a similar reduction of in vitro transcriptional activity of NURR1 dimers of about 30-40%. Neither of these amino acid changes, nor any sequence changes whatsoever, were found in patients with Parkinsons disease or control DNA material of normal populations. Am. J. Med. Genet. (Neuropsychiatr. Genet.) 96:808-813, 2000.

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 Parkinsons 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 Parkinsons 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.

Interaction of polymorphisms in the genes encoding interleukin-6 and estrogen receptor beta on the susceptibility to Parkinson's disease.

The multifunctional cytokine interleukin‐6 (IL‐6) is involved in inflammatory processes in the central nervous system and increased levels of IL‐6 have been found in patients with Parkinsons disease (PD). It is known that estrogen inhibits the production of IL‐6, via action on estrogen receptors, thereby pointing to an important influence of estrogen on IL‐6. In a previous study, we reported an association between a G/A single nucleotide polymorphism (SNP) at position 1730 in the gene coding for estrogen receptor beta (ERbeta) and age of onset of PD. To investigate the influence of a G/C SNP at position 174 in the promoter of the IL‐6 gene, and the possible interaction of this SNP and the ERbeta G‐1730A SNP on the risk for PD, the G‐174C SNP was genotyped, by pyrosequencing, in 258 patients with PD and 308 controls. A significantly elevated frequency of the GG genotype of the IL‐6 SNP was found in the patient group and this was most obvious among patients with an early age of onset (≤50 years) of PD. When the GG genotypes of the IL‐6 and ERbeta SNPs were combined, the combination was much more robustly associated with PD, and especially with PD with an early age of onset, than respective GG genotype when analyzed separately. Our results indicate that the G‐174C SNP in the IL‐6 promoter may influence the risk for developing PD, particularly regarding early age of onset PD, and that the effect is modified by interaction of the G‐1730A SNP in the ERbeta gene.

Lack of association between the BDNF Val66Met polymorphism and Parkinson's disease in a Swedish population.

Polymorphism and Parkinson’s Disease in a Swedish Population Anna Håkansson, MS, Jonas Melke, MS, Lars Westberg, BS, Haydeh Niazi Shahabi, MS, Silva Buervenich, PhD, Andrea Carmine, MS, Kjell Klingborg, MD, Maj-Britt Grundell, MD, Barbara Schulhof, MD, Björn Holmberg, MD, PhD, Jarl Ahlberg, MD, Elias Eriksson, PhD, Olof Sydow, MD, PhD, Lars Olson, PhD, Bo Johnels, MD, PhD, and Hans Nissbrandt, MD, PhD

Investigation of genes coding for inflammatory components in Parkinson's disease

Several findings obtained recently indicate that inflammation may contribute to the pathogenesis in Parkinsons disease (PD). Genetic variants of genes coding for components involved in immune reactions in the brain might therefore influence the risk of developing PD or the age of disease onset. Five single nucleotide polymorphisms (SNPs) in the genes coding for interferon‐γ (IFN‐γ; T874A in intron 1), interferon‐γ receptor 2 (IFN‐γ R2; Gln64Arg), interleukin‐10 (IL‐10; G1082A in the promoter region), platelet‐activating factor acetylhydrolase (PAF‐AH; Val379Ala), and intercellular adhesion molecule 1 (ICAM‐1; Lys469Glu) were genotyped, using pyrosequencing, in 265 patients with PD and 308 controls. None of the investigated SNPs was found to be associated with PD; however, the G1082A polymorphism in the IL‐10 gene promoter was found to be related to the age of disease onset. Linear regression showed a significantly earlier onset with more A‐alleles (P = 0.0095; after Bonferroni correction, P = 0.048), resulting in a 5‐year delayed age of onset of the disease for individuals having two G‐alleles compared with individuals having two A‐alleles. The results indicate that the IL‐10 G1082A SNP could possibly be related to the age of onset of PD.

Association between the estrogen receptor beta gene and age of onset of Parkinson’s disease

The purpose of this study was to investigate the potential contribution of genetic variants in the estrogen receptor beta gene to the aetiology of Parkinsons disease (PD). Several lines of evidence from human and animal studies suggest a protective role for estrogen in PD. Recently the estrogen receptor beta subtype was reported to be an important mediator of estrogen actions in the nigrostriatal dopamine system. Two single nucleotide polymorphisms at position 1730 and 1082 in the ER beta gene were genotyped, using pyrosequencing, in 260 patients with PD and 308 controls recruited from the Swedish population. Neither of the two estrogen receptor beta polymorphisms was associated with an increased risk for PD. However, the G allele of the A1730G polymorphism was more frequent in patients with an early age of onset than in patients with a late age of onset of PD (P = 0.006). Patients carrying the GG genotype had an odds ratio of 2.2 for having an early onset of PD compared to non-carriers. In conclusion, our results indicate that genetic variation in the estrogen receptor beta gene may influence the age of onset of PD.

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 Parkinsons 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.

Alcohol dehydrogenase alleles in Parkinson's disease.

Mutations in alcohol dehydrogenase (ADH; EC 1.1.1.1) genes may be of interest in the etiology of Parkinsons disease (PD) because of the important role these enzymes play in retinoid and dopamine metabolism and/or aldehyde detoxification. The location of several alcohol dehydrogenase genes in a cluster on chromosome 4 lends further support to ADH genes being candidates for this disorder, because recently a form of autosomal‐dominant parkinsonism has been mapped to this area. We sequenced the promoter and coding regions and part of the introns of the human class IV ADH gene in 10 patients with PD. Seven different polymorphisms were identified. These polymorphisms could be assigned to four alleles (A1–A4). We then determined the frequencies of those four alleles and the wild‐type allele in 78 patients with PD and 130 control subjects and found a significant association of the A1 allele with PD (odds ratio = 2.87; 95% confidence interval = 1.35–6.08). In familial cases, the association was strongest (odds ratio = 4.86; 95% confidence interval = 1.89–12.75). Two patients were homozygous for A1 whereas none of the 130 control subjects was found to be homozygous. Our results show an association between a certain ADH4 (formerly known as ADH7 in humans) allele and PD. This suggests a role for genetic variations of ADH4 as risk factors for the development of PD. Our data also show that the observed polymorphisms alone are not sufficient to cause symptoms. Further genetic and/or environmental factors have to be involved.

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 Parkinsons 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 Parkinsons 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 χ2 test. Results remained significant with a two‐sided χ2 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.