Alcohol dependence and polymorphisms of serotonin-related genes: association studies

Variations in 5HT-related genes contribute to the alterations of serotonergic neurotransmission, which is implicated in the etiopathology of alcoholism. In this preliminary study we have tested polymorphisms of genes involved in 5HT transport and turnover for their association with alcohol dependence. A case group of males with type 2 alcoholism (N=59) and a control group of healthy males (N=282), both of Croatian origin, were analyzed for the frequency distribution of polymorphisms in 5HT transporter (5HTT-VNTR2, 5HTT-LPR), monoamine oxidase A (MAOA-uVNTR) and B (MAOB-A/G) and tryptophan hydroxylase 1 (TPH1 A218C) and 2 (TPH2 G-703T) genes. An increase in the frequencies of 10-repeat allele (p = 0.010; OR = 1.73; 95% CI = 1.14-2.60) and 10/10 genotype (p = 0.006; OR = 2.57; 95% CI = 1.32-5.00) of the 5HTT-VNTR2 polymorphism was found in alcoholic patients. No differences between case and control groups were observed for the other tested polymorphisms. Present results support earlier studies implicating the role of 5HTT gene in alcoholism. The increase of sample size (in progress) is expected to enable search of more subtle differences, as well as re-evaluation of these preliminary findings.     

Alcohol dependence, temper and personality

This review focuses on classical and recent research work in the field of alcohol dependence. Data from psychopathological studies trying to determine a "pre-addictive" personality are exposed. More recent studies assess personality disorders and dimensions of temperament associated to alcohol dependence. Sensation seeking, antisocial personality and novelty seeking appear as the main psychological parameters involved in dependence. Sensation seeking is a dimension of personality often associated to behavioral dependence. Sensation seeking is assessed with a five-component scale including general factor, thrill and adventure seeking, experience-seeking, disinhibition, and boredom susceptibility. Patients presenting alcohol dependence have a higher level of sensation seeking. Neurophysiological and genetic studies try to correlate these personality features to biological parameters. Preliminary results of these works are presented and discussed.     

Alcohol dependence patterns and their impact on New York City

As a follow-up to a national survey by the Community Anti-Drug Coalitions of America (CADCA), an expert panel was convened to discuss local alcoholism data from New York, NY. The impact of alcoholism on the US economy is estimated at $185 billion annually. About 15% of New Yorkers drink alcohol excessively, with the highest percentage in Manhattan (22%). Over 135,000 New York City residents are admitted for alcohol treatment. Alcohol dependency is highest among whites (21%), followed by Latinos (14.8%) and African Americans (11%). Despite lower levels of excessive drinking, African-American and Latino New Yorkers are more likely than white New Yorkers to be hospitalized or die as a result of excessive drinking. The barriers to overcome are the lack of information on treatment options, the stigma of alcoholism, the lack of physician education, and a limited number of treatment facilities/personnel. Patients need behavioral counseling, a commitment to treatment, and compliance with medication if they are to succeed in treatment.     

酒精依赖相关基因的遗传多态性

酒精依赖综合征受到复杂的生理、心理、个体遗传及环境等诸多因素的影响。有关研究已经证实了某些候选基因和酒精依赖密切相关。文章主要对与酒精依赖相关的酒精代谢关键酶(乙醇脱氢酶和乙醛脱氢酶以及细胞色素P450 2E1)基因以及调节神经递质作用的酶和受体(儿茶酚氧位甲基转移酶, 多巴胺受体D2、D4, μ阿片受体)基因遗传多态性研究作一综述。     

Association of CHRM2 polymorphisms with severity of alcohol dependence

The cholinergic muscarinic 2 receptor (CHRM2) gene has been considered a candidate gene for the alcohol dependence in that it might underpin certain risk factors for this condition. This study examined variations in the CHRM2 between the patients with alcohol dependence and population controls in Korean and explored the associations between CHRM2 polymorphisms and severity of symptoms in the patients with alcohol dependence. One hundred and fifty-five patients with alcohol dependence, defined by the Alcohol Use Disorders Identification Test (AUDIT) and the Alcohol Dependence Scale (ADS) to measure the severity of symptoms, and one hundred and ninety-five population controls were drawn in the study. Three single nucleotide polymorphisms (SNPs) of CHRM2 were genotyped using the TaqMan assay and analyzed with the severity of symptoms of alcohol dependence. We found that although SNP rs324650 showed marginal association with the risk of alcohol dependence (P = 0.03), the significance of the result was not sustained after multiple corrections. SNP rs1824024 was significantly associated with the AUDIT and ADS scores in patients (P = 0.005 and 0.003, respectively). These findings suggested that the muscarinic acetylcholine function might be related not with alcohol dependence itself but with the severity of alcohol dependence in Korean population.     

Human ferritin genes: chromosomal assignments and polymorphisms.

The ferritins are a family of proteins that function intracellularly to sequester iron that otherwise would be toxic to the cell. The molecules are comprised of 24 heavy and light subunits, the heavy:light ratio varying widely in a tissue-specific manner. We cloned DNA sequences for both the heavy (HL217-1) and light (HL227) subunits from a cDNA library derived from messages that are strongly regulated during in vitro-induced differentiation of a promyelocytic leukemia cell line, HL-60, into either neutrophils or macrophages. The heavy-subunit family (FTH) includes 15-20 genes and/or pseudogenes; the light-subunit family (FTL) includes at least three genes. We have confirmed and extended the chromosomal localization of the heavy-subunit "genes" to chromosomes 1-6, 8, 9, 11, 13, 14, 17, and X. We have also identified and characterized two genetic polymorphisms: FTH/BamHI and FTH/TaqI. FTH/BamHI localizes to chromosome 3, is biallelic, and has a heterozygosity frequency of .39, a minor allele frequency of .33, and a polymorphic information content (PIC) of .34. FTH/TaqI is measured by the presence or absence of a single 6-kb fragment that is absent (i.e., "homozygosity" being presumed) in approximately 63% of Caucasians (PIC = .27). We discuss the possibility that gene-family probes that hybridize to many discrete members of dispersed gene families could be used in conjunction with pulsed- or inverted-field gels to screen a large number of specific genomic regions for microdeletions.     

Association of Fc gamma-receptor genes polymorphisms with chronic periodontitis and Peri-Implantitis

This study was conducted on 87 patients with chronic periodontitis (CP), 50 patients with peri-implantitis and 90 periodontally healthy individuals referring to the Department of Periodontics for evaluating the association between Fc gamma-receptor genes polymorphisms with CP and peri-implantitis. After obtaining consent, venous blood samples (5cc) were obtained from patients and DNA was extracted using Miller's salting-out method. Polymerase chain reaction (PCR)-restriction fragment length polymorphism and tetra-primer amplification refractory mutation system-PCR methods were used to assess the polymorphisms of FcγRs IIa, IIIa, and IIIb genes. Analyzing showed a significant association between specific genotypes with increasing CP and peri-implantitis risks in codominant and dominant models. For FcγR IIIa, analyzing revealed a significant association between specific genotypes with increasing CP and peri-implantitis risks in codominant, dominant, and recessive models. For FcγR IIIb, we also detected a significant association between specific genotypes with increasing CP and peri-implantitis risks in codominant, dominant, and recessive models ( P < 0.05). According to the results of this study, the FCGRIIa (rs1801274), FCGRIIIa (rs396991), and FCGRIIIb (rs1050501) polymorphisms were significantly associated with CP and peri-implantitis and may have a role in the pathogenesis of these diseases.     

High proportions of deleterious polymorphisms in constrained human genes

Previous studies on human mitochondrial genomes showed that the ratio of intra-specific diversities at nonsynonymous-to-synonymous positions was two to ten times higher than the ratio of interspecific divergences at these positions, suggesting an excess of slightly deleterious nonsynonymous polymorphisms. However, such an overabundance of nonsynonymous single nucleotide polymorphisms (SNPs) was not found in human nuclear genomes. Here, genome-wide estimates using >14,000 human-chimp nuclear genes and 1 million SNPs from four human genomes showed a significant proportion of deleterious nonsynonymous SNPs (～ 15%). Importantly, this study reveals a negative correlation between the magnitude of selection pressure and the proportion of deleterious SNPs on human genes. The proportion of deleterious amino acid replacement polymorphisms is 3.5 times higher in genes under high purifying selection compared with that in less constrained genes (28% vs. 8%). These results are explained by differences in the extent of contribution of mildly deleterious mutations to diversity and substitution.     

False positive non-synonymous polymorphisms of G-protein coupled receptor genes

Polymorphisms of G-protein coupled receptor (GPCR) genes are associated with disease risk and modification, and the response to receptor-directed therapy. Genomic sequencing ( approximately 1700 automated runs) from as many as 120 chromosomes from 60 multiethnic individuals was performed to confirm non-synonymous coding polymorphisms reported in the dbSNP database from 25 randomly selected GPCR genes. These polymorphisms were in regions of the receptors responsible for structural integrity, ligand binding, G-protein coupling and phosphoregulation. However, most of these putative polymorphisms could not be confirmed (false positive rate of 68%). Based on these results, we suggest that the variability of the superfamily is not well defined, and we caution against exclusive reliance on databases for selection of candidate GPCR polymorphisms for disease association and pharmacogenetic studies.     

Rat brain de-acetylating activity: stereospecific inhibition by LSD and serotonin-related compounds.

A de-acetylase (aryl acylamidase, E.C.3.5.1.13) has been isolated and partially characterized from rat brain. Previous studies have shown that this enzymatic activity is inhibited by low concentrations of serotonin. This report examines the effects of closely related tryptamine derivatives and demonstrates that enzymatic activity is stereospecifically inhibited by LSD. Similar enzymatic activity from liver was found to be insensitive to any of the compounds tested. The significance of these findings with regard to well known serotonin-LSD interactions is discussed.     

A copula method for modeling directional dependence of genes

Background  

Genes interact with each other as basic building blocks of life, forming a complicated network. The relationship between groups of genes with different functions can be represented as gene networks. With the deposition of huge microarray data sets in public domains, study on gene networking is now possible. In recent years, there has been an increasing interest in the reconstruction of gene networks from gene expression data. Recent work includes linear models, Boolean network models, and Bayesian networks. Among them, Bayesian networks seem to be the most effective in constructing gene networks. A major problem with the Bayesian network approach is the excessive computational time. This problem is due to the interactive feature of the method that requires large search space. Since fitting a model by using the copulas does not require iterations, elicitation of the priors, and complicated calculations of posterior distributions, the need for reference to extensive search spaces can be eliminated leading to manageable computational affords. Bayesian network approach produces a discretely expression of conditional probabilities. Discreteness of the characteristics is not required in the copula approach which involves use of uniform representation of the continuous random variables. Our method is able to overcome the limitation of Bayesian network method for gene-gene interaction, i.e. information loss due to binary transformation.