RefPrimeCouch--a reference gene primer CouchApp.

To support a quantitative real-time polymerase chain reaction standardization project, a new reference gene database application was required. The new database application was built with the explicit goal of simplifying not only the development process but also making the user interface more responsive and intuitive. To this end, CouchDB was used as the backend with a lightweight dynamic user interface implemented client-side as a one-page web application. Data entry and curation processes were streamlined using an OpenRefine-based workflow. The new RefPrimeCouch database application provides its data online under an Open Database License. Database URL: http://hpclife.th-wildau.de:5984/rpc/_design/rpc/view.html.

Chronic ethanol exposure changes dopamine D2 receptor splicing during retinoic acid-induced differentiation of human SH-SY5Y cells.

There is evidence for ethanol-induced impairment of the dopaminergic system in the brain during development. The dopamine D2 receptor (DRD2) and the dopamine transporter (DAT) are decisively involved in dopaminergic signaling. Two splice variants of DRD2 are known, with the short one (DRD2s) representing the autoreceptor and the long one (DRD2l) the postsynaptic receptor. We searched for a model to investigate the impact of chronic ethanol exposure and withdrawal on the expression of these proteins during neuronal differentiation. RA-induced differentiation of human neuroblastoma SH-SY5Y cells seems to represent such a model. Our real-time RT-PCR, Western blot, and immunocytochemistry analyses of undifferentiated and RA-differentiated cells have demonstrated the enhanced expression of both splice variants of DRD2, with the short one being stronger enhanced than the long one under RA-treatment, and the DRD2 distribution on cell bodies and neurites under both conditions. In contrast, DAT was down-regulated by RA. The DAT is functional both in undifferentiated and RA-differentiated cells as demonstrated by [(3)H]dopamine uptake. Chronic ethanol exposure during differentiation for up to 4 weeks resulted in a delayed up-regulation of DRD2s. Ethanol withdrawal caused an increased expression of DRD2l and a normalization of DRD2s. Thus the DRD2s/DRD2l ratio was still disturbed. The dopamine level was increased by RA-differentiation compared to controls and was diminished under RA/ethanol treatment and ethanol withdrawal compared to RA-only treated cells. In conclusion, chronic ethanol exposure impairs differentiation-dependent adaptation of dopaminergic proteins, specifically of DRD2s. RA-differentiating SH-SY5Y cells are suited to study the impact of chronic ethanol exposure and withdrawal on expression of dopaminergic proteins during neuronal differentiation.

Haplotypes of dopamine and serotonin transporter genes are associated with antisocial personality disorder in alcoholics.

INTRODUCTION: A different genetic background is postulated for alcoholics with early onset and with antisocial personality disorder (type 2 alcoholics) compared with those with late onset and without antisocial personality disorder (type 1 alcoholics). The dopamine transporter (DAT) and the serotonin transporter (SERT) are involved in endophenotypes that are associated with these subtypes. Our study was aimed at investigating whether distinct haplotypes, defined by polymorphisms associated with the expressions of DAT and SERT, were associated with subgroups of alcohol dependence. METHODS: Intron 8 variable number of tandem repeats (VNTR), exon 15 rs27072 and VNTR (DAT), promoter VNTR and rs25531, and intron 2 VNTR (SERT) were genotyped in a case-control sample comprising 360 alcoholics and 368 controls, and in a family-based sample of 65 trios, all of German origin. RESULTS: DAT: The haplogenotypes 6-A-10/6-G-10 and 5-G-9/5-G-9 were more often present in type 2 alcoholics as compared with type 1 alcoholics [odds ratio (OR): 2.8], and controls (OR: 5.8), respectively. The daily ethanol consumption was associated with haplogenotypes. SERT: haplotypes SA-10 (OR: 2.3) and LG-12 (OR: 2.5) were more often present in type 2 alcoholics compared with controls. Haplotype LA-10 was less often present in type 2 alcoholics (OR: 0.5), and was more often transmitted, in families, to the affected offspring (transmission disequilibrium test: OR: 5.2; family-based association test: Z: 1.9). The haplotype LA-12 was significantly undertransmitted to affected offspring in the whole group (transmission disequilibrium test: OR: 0.216; family-based association test: Z: -2.2). A gene by environment interaction was observed with respect to the time course of the depression score after alcohol withdrawal and with respect to the positive family history of alcohol dependence. CONCLUSION: Haplotype analysis, sub-grouping with respect to more homogeneous endophenotypes, and inclusion of quantifiable characteristics are sensible strategies to untangle the genetic background of such a complex disorder like alcohol dependence.

9-Methyl-beta-carboline has restorative effects in an animal model of Parkinson's disease.

In a previous study, a primary culture of midbrain cells was exposed to 9-methyl-beta-carboline for 48 h, which caused an increase in the number of tyrosine hydroxylase-positive cells. Quantitative RT-PCR revealed increased transcription of genes participating in the maturation of dopaminergic neurons. These in vitro findings prompted us to investigate the restorative actions of 9-methyl-beta-carboline in vivo. The compound was delivered for 14 days into the left cerebral ventricle of rats pretreated with the neurotoxin 1-methyl-4-phenyl-pyridinium ion (MPP+) for 28 days applying a dose which lowered dopamine by approximately 50%. Interestingly, 9-methyl-beta-carboline reversed the dopamine-lowering effect of the neurotoxin in the left striatum. Stereological counts of tyrosine hydroxylase-immunoreactive cells in the substantia nigra revealed that the neurotoxin caused a decrease in the number of those cells. However, when treated subsequently with 9-methyl-beta-carboline, the number reached normal values. In search of an explanation for the restorative activity, we analyzed the complexes that compose the respiratory chain in striatal mitochondria by 2-dimension gel electrophoresis followed by MALDI-TOF peptide mass fingerprinting.We found no changes in the overall composition of the complexes. However, the activity of complex I was increased by approximately 80% in mitochondria from rats treated with MPP+ and 9-methyl-beta-carboline compared to MPP+ and saline and to sham-operated rats, as determined by measurements of nicotinamide adenine dinucleotide dehydrogenase activity. Microarray technology and single RT-PCR revealed the induction of neurotrophins: brain-derived neurotrophic factor, conserved dopamine neurotrophic factor, cerebellin 1 precursor protein, and ciliary neurotrophic factor. Selected western blots yielded consistent results. The findings demonstrate restorative effects of 9-methyl-beta-carboline in an animal model of Parkinson's disease that improve the effectiveness of the respiratory chain and promote the transcription and expression of neurotrophin-related genes.

Raf kinase inhibitor protein enhances neuronal differentiation in human SH-SY5Y cells.

Neuronal differentiation has evolved as an essential process even in the adult brain, once disturbed being associated with the pathogenesis of several psychiatric disorders. To study the effects of Raf kinase inhibitor protein (RKIP) on neuronal differentiation, we generated neuroblastoma cell lines overexpressing RKIP (RKIP(+)) and expressing RKIP-directed short hairpin RNA for downregulation of RKIP (RKIP(-)). During a 4-week time course of continuous differentiation by retinoic acid (RA), expression of neuronal and glial markers, intracellular cyclic adenosine monophosphate (cAMP) levels, protein kinase C (PKC) signal transduction to extracellular signal-regulated kinase 1/2 (ERK-1/2) and cellular morphology were investigated in relation to RKIP levels. RKIP(+) cells showed accelerated neurite outgrowth, formation of elaborated neuronal networks and increased neuronal marker expression both in RA-induced differentiation and to some extent even in non-RA-treated cells. RKIP(-) cells showed glial-like cell bodies and increased glial fibrillary acidic protein, suggesting a shift from neuronal to glial phenotype. With respect to differentiation-inducing signal pathways, PKC-mediated ERK-1/2 activation significantly correlated with RKIP levels. Furthermore, basal and forskolin-stimulated intracellular cAMP was potently increased in RKIP(+) cells versus controls. In conclusion, the conserved signal transduction modulator RKIP was shown to enhance several aspects of neuronal differentiation via enhanced crosstalk from PKC to ERK-1/2 and enhancement of G-protein-coupled receptor signaling.

Serotonin transporter promoter polymorphism and dopaminergic sensitivity in alcoholics.

The central serotonin (5-HT) system plays an important role in the rewarding and addictive properties of alcohol by a direct activation of the mesolimbic dopamine (DA) system. An insertion/deletion (L/S) promoter polymorphism (5-HTTLPR) of the 5-HT transporter (5-HHT) gene (SLC6A4) has been shown to influence transcriptional activity. It is predicted that reduced transynaptic 5-HT neurotransmission in alcoholics with the L/L genotype of 5-HTTLPR would result in a change in DA function compared to the S/S genotype. Thus the present study has tested whether dopaminergic sensitivity is influenced by the 5-HTTLPR genotype. Dopaminergic sensitivity, 5-HTTLPR genotype and smoking status were assessed in 121 alcoholics. Dopaminergic sensitivity as an indicator of the functional state of the dopaminergic system was measured by the amount of growth hormone (GH) secretion after subcutaneous administration of apomorphine (APO, 0.01 mg/kg). 5-HTTLPR genotype was significantly associated with dopaminergic sensitivity (P = 0.004) explaining 9.2% of the variance of GH response. Subjects homozygous for the L allele (with high 5-HTT expression) showed the lowest GH response, whereas those homozygous for the S allele (with low 5-HTT expression) showed the highest GH response (this was intermediate in heterozygous participants). Furthermore smoking was associated with a significantly reduced GH response (P = 0.006). Our findings indicate that the postsynaptic dopaminergic sensitivity is influenced by the 5-HTTLPR genotype. It is hypothesized that the reduction of sensitivity of the central DA receptors in alcoholics with the L/L genotype might be due to their higher vulnerability to the neurotoxic effects of chronic alcohol consumption than the S carriers.

Association of the dopamine D2 receptor gene with alcohol dependence: haplotypes and subgroups of alcoholics as key factors for understanding receptor function.

OBJECTIVES: The dopamine D2 receptor (DRD2) plays an important role in the reinforcing and motivating effects of ethanol. Several polymorphisms have been reported to affect receptor expression. The amount of DRD2, expressed in a given individual, is the result of the expression of both alleles, each representing a distinct haplotype. We examined the hypothesis that haplotypes composed of polymorphisms, associated with reduced receptor expression, are more frequent in alcoholics compared with healthy individuals. METHODS: The polymorphisms -141ins/del, C957T, A1385G, and TaqlA were genotyped in a case-control sample comprising 360 alcoholics and 368 controls, and in a family-based sample of 65 trios. To investigate more homogenous groups, we constructed two subgroups with respect to age at onset and antisocial personality disorder. In addition, a subgroup with positive family history of alcoholism was investigated. RESULTS: The haplotypes I-C-G-A2 and I-C-A-A1 occurred with a higher frequency in alcoholics [P=0.026, odds ratio (OR): 1.340; P=0.010, OR: 1.521, respectively]. The rare haplotype I-C-A-A2 occurred less often in alcoholics (P=0.010, OR: 0.507), and was also less often transmitted from parents to their affected offspring (1 vs.7). Among the subgroups, I-C-G-A2 and I-C-A-A1 had a higher frequency in Cloninger 1 alcoholics (P=0.083 and 0.001, OR: 1.917, respectively) and in alcoholics with a positive family history (P=0.031, OR: 1.478; P=0.073, respectively). Cloninger 2 alcoholics had a higher frequency of the rare haplotype D-T-A-A2 (P<0.001, OR: 4.614) always compared with controls. In patients with positive family history haplotype I-C-A-A2 (P=0.004, OR: 0.209), and in Cloninger 1 alcoholics haplotype I-T-A-A1 (P=0.045 OR: 0.460) were less often present. CONCLUSION: We confirmed the hypothesis that haplotypes, which are supposed to induce a low DRD2 expression, are associated with alcohol dependence. Furthermore, supposedly high-expressing haplotypes weakened or neutralized the action of low-expressing haplotypes.

Long-term ethanol exposure impairs neuronal differentiation of human neuroblastoma cells involving neurotrophin-mediated intracellular signaling and in particular protein kinase C.

BACKGROUND: Revealing the molecular changes in chronic ethanol-impaired neuronal differentiation may be of great importance for understanding ethanol-related pathology in embryonic development but also in the adult brain. In this study, both acute and long-term effects of ethanol on neuronal differentiation of human neuroblastoma cells were investigated. We focused on several aspects of brain-derived neurotrophic factor (BDNF) signaling because BDNF activates the extracellular signal-regulated kinase (ERK) cascade, promoting neuronal differentiation including neurite outgrowth. METHODS: The effects of ethanol exposure on morphological differentiation, cellular density, neuronal marker proteins, basal ERK activity, and ERK responsiveness to BDNF were measured over 2 to 4 weeks. qRT-PCR and Western blotting were performed to investigate the expression of neurotrophin receptor tyrosin kinase B (TrkB), members of the ERK-cascade, protein kinase C (PKC) isoforms and Raf-Kinase-Inhibitor-Protein (RKIP). RESULTS: Chronic ethanol interfered with the development of a neuronal network consisting of cell clusters and neuritic bundles. Furthermore, neuronal and synaptic markers were reduced, indicating impaired neuronal differentiation. BDNF-mediated activation of the ERK cascade was found to be continuously impaired by ethanol. This could not be explained by expressional changes monitored for TrkB, Raf-1, MEK, and ERK. However, BDNF also activates PKC signaling which involves RKIP, which finally leads to ERK activation as well. Therefore, we hypothesized that ethanol impairs this branch of BDNF signaling. Indeed, both PKC and RKIP were significantly down-regulated. CONCLUSIONS: Chronic ethanol exposure impaired neuronal differentiation of neuroblastoma cells and BDNF signaling, particularly the PKC-dependent branch. RKIP, acting as a signaling switch at the merge of the PKC cascade and the Raf/MEK/ERK cascade, was associated with neuronal differentiation and significantly reduced in ethanol treatment. Moreover, PKC expression itself was even more strongly reduced. In contrast, members of the Raf-1/MEK/ERK cascade were less affected and the observed changes were not associated with impaired differentiation. Thus, reduced RKIP and PKC levels and subsequently reduced positive feedback on ERK activation provide an explanation for the striking effects of long-term ethanol exposure on BDNF signal transduction and neuronal differentiation, respectively.

9-Methyl-beta-carboline up-regulates the appearance of differentiated dopaminergic neurones in primary mesencephalic culture.

beta-Carbolines (BCs) derive from tryptophan and its derivatives. They are formed endogenously in humans and mammals and occur inter alia in cooked meat and tobacco smoke. They have been detected in human brain, cerebrospinal fluid, and plasma. Up to now they were predominantly identified as compounds exhibiting neurotoxic actions. Since significantly higher amounts are present in parkinsonian patients, they are regarded as potential pathogenetic factors in Parkinson's disease. We identified for the first time a BC (9-methyl-BC; 9-me-BC) exerting neuroprotective and neuron-differentiating effects. Treatment of primary mesencephalic dopaminergic cultures with 9-me-BC inhibited the basal release of lactate dehydrogenase and reduced the number of cells stained with propidium iodide. Caspase-3 activity was decreased, the total protein content was unchanged and ATP content was increased. Furthermore, the expression of inflammation-related genes was reduced. The number of differentiated dopaminergic neurones was significantly increased and a wide array of neurotrophic/transcription factors (Shh, Wnt1, Wnt5a, En1, En2, Nurr1, Pitx3) and marker genes (Th, Dat, Aldh1a1) decisive for dopaminergic differentiation was stimulated. Consistently, the dopamine content was slightly, although non-significantly, increased and the dopamine uptake capacity was elevated. An anti-proliferative effect was observed in human neuroblastoma SH-SY5Y cells which is consistent with a reduced incorporation of bromodesoxyuridine into the DNA of primary mesencephalic cells. Whether the additional dopaminergic neurones in primary culture derive from dopaminergic precursor cells, previously tyrosine hydroxylase negative dopaminergic neurones or are the result of a transdifferentiation process remains to be established.

Cytotoxicity of beta-carbolines in dopamine transporter expressing cells: structure-activity relationships.

Some beta-carbolines (BC) are natural constituents in the human brain deriving from tryptophan, tryptamine, and serotonin. In vitro and animal experiments suggest that BC-cations may cause neurodegeneration with a higher vulnerability of dopaminergic than of other neurons. Despite the possible implication of the BC-cations in the pathogenesis of Parkinson's disease (PD), the underlying mechanisms are poorly understood. The present study further explores the structural requirements for the cytotoxic effects of BCs and searches for additional compounds involved in the pathogenesis of PD. Previous studies were now extended to serotonin-derived BCs, tetrahydro-BCs, a BC-dimer, and a BC-enantiomer to reveal possible stereoselectivity. Neutral, rather lipophilic BCs may pass the plasma membrane and the outer and inner mitochondrial membranes by diffusion whereas the cationic, more polar compounds, can be transported by the dopamine transporter (DAT). In the present study, 4 out of 17 BC-cations caused DAT-independent toxicity. This number is unexpected in view of previous findings that all BC-cations are transported by DAT. 3-Carboxylated and 6-methoxylated BCs were poor substrates. The size alone does not seem to be a limiting factor. A dimeric BC-cation was readily transported by the DAT despite its much larger structure compared to dopamine. Furthermore, (R)-enantiomers were preferentially transported. The neutral BCs were approximately one order of magnitude less toxic than the cationic BCs. There are considerable differences of the transport efficiency between the BCs. Potent cytotoxic tetrahydro-BCs were detected. Because precursor tetrahydro-BCs are present in the brain, the search for the occurrence of these compounds in human brain is warranted.

Parkinson's disease-like syndrome in rats induced by 2,9-dimethyl-beta-carbolinium ion, a beta-carboline occurring in the human brain.

Regarding the pathogenesis of Parkinson's disease, a neurotoxin hypothesis was proposed following the discovery that 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) produces a Parkinson-like syndrome in humans and primates. Since then, researchers have searched for endogenous and exogenous compounds that are structurally similar to this neurotoxin. Such compounds include beta-carbolines, formed from tryptophan and its derivatives. beta-carbolines are present naturally in the human brain and cerebrospinal fluid. The present study examined the effect of bilateral, intranigral administration of 2,9-dimethyl-beta-carbolinium ion on muscle tone, electromyographic activity, dopamine metabolism in the striatum, and the number of tyrosine hydroxylase-immunoreactive neurons and volume of the substantia nigra in rats. We found that the beta-carbolinium ion (15 or 40 nmol per side) caused a significant decrease in the striatal levels of dopamine and its metabolites, which was accompanied by an enhancement of muscle tone and electromyographic activity. Stereological counting revealed that the beta-carbolinium caused a significant decrease in the total number of tyrosine hydroxylase-immunoreactive neurons and shrinkage of the substantia nigra. The findings suggest that the methylated beta-carbolinium ion produces a dose-dependent degeneration of nigrostriatal neurons, leading to deficits in dopaminergic neurotransmission and an increase of muscle resistance and electromyographic activity, a syndrome equivalent to muscle rigidity in Parkinson's disease.

Association of human hippocampal neurochemistry, serotonin transporter genetic variation, and anxiety.

The impact of the serotonin transporter (5-HTT) gene-linked polymorphic region (5-HTTLPR) on anxiety-related behavior and related cerebral activation has facilitated the understanding of neurobiological mechanisms of anxiety. However, the influence of the 5-HTTLPR genotype on hippocampal neuronal development and neurochemistry, which is relevant to anxiety behavior, has not been investigated. In 38 healthy subjects, absolute concentrations of N-acetylaspartate (NAA) were measured as a main surrogate parameter for hippocampal neurochemistry on a 3-T scanner. A significantly lower hippocampal NAA concentration in s allele carriers was observed as compared to l/l genotype. Other metabolites (choline, creatine + phosphocreatine, glutamate) were unaffected by genotype. The hippocampal NAA concentration was negatively correlated with trait anxiety scores (STAI). Metabolites measured in the anterior cingulate cortex (reference region) were not associated with genotype. The results are in accordance with the recently reported relationship between hippocampal neuronal development and anxiety behavior in adult animals and show an association between human limbic neurochemistry and genetically driven serotonergic neurotransmission relevant to anxiety.

No association of a functional polymorphism in the serotonin transporter gene promoter and anxiety-related personality traits.

Serotonergic neurotransmission, which is involved in many psychiatric disorders, is mediated by the serotonin transporter protein. Gene coding for the serotonin transporter protein is designated SLC6A4, which has been differentially associated with anxiety-related behavioral traits and neuroticism in healthy subjects. To confirm the association between the serotonin transporter (5-HTT) gene-linked polymorphic region (5-HTTLPR) and anxiety-related personality traits, we examined 228 healthy unrelated participants (age 38.6 +/- 12.8 years; 115 male, 113 female) of German origin, who were carefully examined with respect to psychiatric health. The self-ratable State-Trait Anxiety Inventory (STAI) and the NEO Five Factor Inventory (NEO-FFI) were performed. No significant association was observed between the 5-HTTLPR genotype and STAI 1 (state, chi2 = 0.82, p < 0.66, d.f. = 2), STAI 2 (trait, chi2 = 2.7, p < 0.25, d.f. = 2) and NEO-FFI scores of any of the 5 major axes, including neuroticism (chi2 = 3.35, p < 0.18, d.f. = 2) in all subjects. Given the small effect of this 5-HTT polymorphism on behaviour in previous studies, a lack of significant genotype differences in these tests could be due to considerable individual variability in these measures.

Polymorphisms in the N-methyl-D-aspartate receptor 1 and 2B subunits are associated with alcoholism-related traits.

BACKGROUND: This study examined the hypothesis that allelic variants of the ionotropic glutamatergic N-methyl-D-aspartate receptor (NMDAR) are associated with vulnerability to alcoholism and some related traits. METHODS: We investigated the silent G2108A and C2664T polymorphisms of the NMDAR1 and the NMDAR2B genes, respectively. The case control study included 367 alcoholic and 335 control subjects of German origin. The family-based study comprised 81 Polish alcoholic patients and their parents using the transmission disequilibrium test. RESULTS: The genotype frequencies of the NMDAR1 polymorphism differed significantly between control and alcoholic subjects. This difference was also observed in more homogenous subgroups of alcoholic subjects with vegetative withdrawal syndrome and Cloninger type 1. Patients with a history of delirium tremens or seizures during withdrawal showed a significantly increased prevalence of the A allele. Genotyping of the NMDAR2B polymorphism revealed a significantly reduced T allele in Cloninger type 2 alcoholics and in patients reporting an early onset compared with control subjects. Our family-based study for NMDAR2B, revealed a trend to a preferred transmission of the C allele by the fathers, and families with early-onset patients contributed most to this trend. CONCLUSIONS: These results suggest that variants in NMDAR genes are associated with alcoholism and related traits.

Allelic variants of the functional promoter polymorphism of the human serotonin transporter gene is associated with auditory cortical stimulus processing.

The loudness dependence (LD) of the auditory-evoked N1/P2 component has been shown to be related to the central serotonergic neurotransmission. Allelic variants in the promoter region of the 5-hydroxytryptamine transporter (5-HTT) gene were shown to modulate serotonergic activity. It was hypothesized that the three genotypes (l/l, s/l, s/s) differ with respect to LD. Allelic variants of the 5-HTT promoter region and LD at the Cz electrode were determined in 185 healthy subjects prospectively. A significant association was found between LD and genotype (ANOVA: F=4.172, p=0.017). Individuals homozygous for the l allele exhibited a weaker LD compared to heterozygous subjects. The results are consistent with the reported association between 5-HTT genotype and serotonin transport capacity in lymphoblasts, and indicate that auditory stimulus processing is associated with genetic variants of the brain serotonergic system. The LD may serve as endophenotype in human serotonin research.

Norepinephrine transporter gene polymorphism is not associated with susceptibility to alcohol dependence.

Abnormalities in monoamine neurotransmission have been implicated in the pathogenesis of alcoholism, mood disorders and schizophrenia. Murine norepinephrine transporter gene (NET) has been mapped to a region on chromosome 8 where a quantitative trait locus for ethanol sensitivity. Therefore we tested whether norepinephrine transporter (NET) gene variants confer susceptibility to either alcohol dependence or severe alcohol withdrawal symptoms. There is a highly polymorphic silent G1287A mutation in the NET gene. In our study 157 alcoholics and 185 healthy unrelated matched control subjects were analyzed for a silent G1287A mutation. No significant differences in allele and genotype distribution between control subjects f(A)=0.33 and alcoholics f(A)=0.29 were found. No significant results were found in more homogenous subgroups, i.e. alcoholics with severe alcohol withdrawal (seizures, delirium), early onset age<26 nor dependent patients with positive familial history of alcoholism. These results suggest that the NET gene polymorphism in exon 9 accession number: mRNA: NM_001043, genomic contig.: NT_019610, is unlikely to be involved in the susceptibility to alcoholism and severe alcohol withdrawal.

Evidence for the importance of the human dopamine transporter gene for withdrawal symptomatology of alcoholics in a German population.

Two new polymorphisms in the 3' untranslated region (3'UTR) of the dopamine transporter (DAT1) gene, adjacent to the known variable number of tandem repeats (VNTR) polymorphism, have been investigated in the present population-based association study including 351 alcoholics and 336 controls. The DraI restriction site was not polymorphic in our population. The G2319A polymorphism was not significantly different with respect to genotype or allele distribution between alcoholics and controls. Subsequently, in individuals with VNTR homozygosity for the ten repeat allele, we found a higher prevalence of A/A homozygosity in patients with seizure history (P = 0.001, odds ratio (OR) = 7.913), with delirium history (P = 0.032, OR = 4.707), and with an alcoholic mother (P = 0.021, OR = 5.250), compared to homozygote 10/10 controls. Our findings provide further evidence that the 3'UTR of the DAT1 gene affects vulnerability to severe alcohol withdrawal.