No Alcoholism-Protection Effects of ADH1B*2 Allele in Antisocial Alcoholics among Han Chinese in Taiwan

Evaluation of the interaction between genetic variants of GAD1 and miRNA in bipolar disorders

BACKGROUND

Glutamic acid dehydrogenase 1 (GAD1) serves as the rate-limiting enzyme for synthesizing GABA, and is reported to be associated with several psychiatric disorders. The present study examined the effects of GAD1 genetic variants on bipolar disorder (BD) and its subtypes. Moreover, we investigated functional interactions between genetic variants and miRNAs via algorithm prediction and experimental validation.

METHODS

A case-control study was conducted with 280 BD patients and 200 healthy controls. Eight tag SNPs in GAD1 were genotyped. For associated markers, we performed in silico prediction for their potential functions through SNP-miRNA interactions by establishing a scoring system to combine information from several miRNA predictive algorithms. We then tested allelic expression differences using Dual-Glo luciferase reporter assays for the selected SNP-miRNA pair. Lastly, we examined the associations of the GAD1 gene and BD in two additional independent datasets with a few thousand samples for replication.

RESULTS

Marker rs3749034 was associated with BD, in particular the BD-II subtype. According to our scoring system, several candidate miRNAs were predicted to interact with rs3749034, and hsa-miR-504 had the highest score. Findings from an in vitro experiment revealed a non-statistically significant trend for lower gene expression level with the A allele of rs3749034 compared with the G allele. The association between rs3749034 and BD was not replicated in either of the independent datasets. Instead, other rarer genetic variants in GAD1 showed suggestive signals (e.g. rs575441409, p-value = 3.8*10^-4, D' = 1 with rs3749034) with BD in the Taiwanese dataset.

LIMITATIONS

The present study considered common genetic variants only. In addition, we only used a 293T cell-line in conducting luciferase reporter assays, as no primary cell-lines from patient samples were available to differentiate the effects between BD subtypes.

CONCLUSIONS

Our results demonstrate a weak effect of the GAD1 gene on the risk of bipolar illness, and the associated marker might represent a proxy for real signals of rare variants.

More inflammation but less brain-derived neurotrophic factor in antisocial personality disorder

Antisocial personality disorder (ASPD) is highly comorbid with substance use disorders (SUDs). We hypothesize that chronic neuroinflammation and the loss of neurotrophic factors prompts the pathogenesis of both disorders. We used ELISA to measure plasma levels of proinflammatory (tumor necrosis factor-α [TNF-α], C-reactive protein [CRP]) and anti-inflammatory factors (transforming growth factor-β1 [TGF-β1] and interleukin-10 [IL-10]), and brain-derived neurotrophic factor (BDNF) in male patients with ASPD (n=74), SUDs (n=168), ASPD comorbid with SUDs (ASPD+SUDs) (n=438), and Healthy Controls (HCs) (n=81). A multivariate analysis of covariance (MANCOVA) controlled for possible confounders was used to compare cytokines and BDNF levels between groups. The results of MANCOVA adjusted for age showed a significant (p<0.001) main effect of diagnosis on inflammatory factors and BDNF expression in these groups. ASPD, SUDs, and ASPD+SUDs patients had significantly (p<0.001) higher TNF-α levels but lower TGF-β1 and BDNF levels. SUDs and ASPD+SUDs patients had higher IL-10 levels than did ASPD patients and HCs. There was no difference in IL-10 levels between HCs and ASPD. Moreover, subgrouping SUDs and ASPD±SUDs into opioid use disorder (OUD) and other SUDs groups showed that the IL-10 levels were specifically higher in OUD and ASPD±OUD groups than other SUDs (P≤0.001). We conclude that uncontrolled inflammation and losing neurotrophic factors, with or without comorbid SUDs, underlies ASPD. IL-10 expression might be more specifically associated with OUD.

Advances in genetic studies of substance abuse in China

Summary

The importance of genetic factors in substance addiction has long been established. The rationale for this work is that understanding of the function of addiction genes and delineation of the key molecular pathways of these genes would enhance the development of novel therapeutic targets and biomarkers that could be used in the prevention and management of substance abuse. Over the past few years, there has been a substantial increase in the number of genetic studies conducted on addiction in China; these studies have primarily focused on heroin, alcohol, and nicotine dependence. Most studies of candidate genes have concentrated on the dopamine, opioid, and serotonin systems. A number of genes associated with substance abuse in Caucasians are also risk factors in Chinese, but several novel genes and genetic risk factors associated with substance abuse in Chinese subjects have also been identified. This paper reviews the genetic studies of substance abuse performed by Chinese researchers. Genotypes and alleles related to addictive behavior in Chinese individuals are discussed and the contributions of Chinese researchers to the international corpus of knowledge about the genetic understanding of substance abuse are described.

Variation of types of alcoholism: review and subtypes identified in Han Chinese

Alcoholism, as it has been hypothesized, is caused by a highly heterogeneous genetic load. Since 1960, many reports have used the bio-psycho-social approach to subtype alcoholism; however, no subtypes have been genetically validated. We reviewed and compared the major single-gene, multiple-gene, and gene-to-gene interaction studies on alcoholism published during the past quarter-century, including many recent studies that have made contributions to the subtyping of alcoholism. Four subtypes of alcoholism have been reported: [1] pure alcoholism, [2] anxiety/depression alcoholism, [3] antisocial alcoholism, and [4] mixed alcoholism. Most of the important studies focused on three genes: DRD2, MAOA, and ALDH2. Therefore, our review focuses on these three genes.

Association study of DRD2 and MAOA genes with subtyped alcoholism comorbid with bipolar disorder in Han Chinese

BACKGROUND

Several studies have hypothesized that genes involved in the dopamine system, including dopamine type-2 receptor (DRD2)-related TaqIA polymorphism and monoamine oxidase-A upstream variable number tandem repeat (uVNTR), may be associated with alcoholism. But their results were contradictory because of alcoholism's heterogeneity. Therefore, we examined whether the DRD2TaqIA and MAOA-uVNTR gene polymorphisms are susceptibility factors for alcoholism comorbid with bipolar disorder (ALC+BP) in Han Chinese in Taiwan.

METHODS

We recruited 101 Han Chinese men with comorbid alcoholism and bipolar disorder, and 328 healthy male controls from the community. Genotyping was done using PCR-RFLP.

RESULTS

There were no significant differences in the genotypic frequencies of the DRD2TaqIA or the MAOA-uVNTR polymorphisms between the 2 groups. The MAOA-uVNTR 3-repeat had a significant protective effect on the ALC+BP (odds ratio=0.432, p=0.035) but not on the healthy controls. However, the interaction between the MAOA-uVNTR 3-repeat and DRD2 A1/A2 was a risk factor in the ALC+BP (odds ratio=3.451, p=0.018).

CONCLUSIONS

We indicated the impact of the association between MAOA-uVNTR 3-repeat and DRD2 A1/A2 with ALC+BP.

Interaction between ALDH2*1*1 and DRD2/ANKK1 TaqI A1A1 genes may be associated with antisocial personality disorder not co-morbid with alcoholism

Previous studies on acetaldehyde dehydrogenase 2 (ALDH2) focused on drinking behavior or alcoholism because the ALDH2*2 allele protects against the risk of developing alcoholism. The mechanism provides that the ALDH2 gene's protective effect is also involved in dopamine metabolism. The interaction of the ALDH2 gene with neurotransmitters, such as dopamine, is suggested to be related to alcoholism. Because alcoholism is often co-morbid with antisocial personality disorder (ASPD), previous association studies on antisocial alcoholism cannot differentiate whether those genes relate to ASPD with alcoholism or ASPD only. This study examined the influence of the interaction effect of the ALDH2*1*1, *1*2 or *2*2 polymorphisms with the dopamine 2 receptor (DRD2) Taq I polymorphism on ASPD. Our 541 Han Chinese male participants were classified into three groups: antisocial alcoholism (ASPD co-morbid with alcohol dependence, antisocial ALC; n = 133), ASPD without alcoholism (ASPD not co-morbid with alcohol dependence, antisocial non-ALC; n = 164) and community controls (healthy volunteers from the community; n = 244). Compared with healthy controls, individuals with the DRD2 A1/A1 and the ALDH2*1/*1 genotypes were at a 5.39 times greater risk for antisocial non-ALC than were those with other genotypes. Our results suggest that the DRD2/ANKK1 and ALDH2 genes interacted in the antisocial non-ALC group; a connection neglected in previous studies caused by not separating antisocial ALC from ASPD. Our study made this distinction and showed that these two genes may be associated ASPD without co-morbid alcoholism.

Interaction between serotonin transporter and serotonin receptor 1 B genes polymorphisms may be associated with antisocial alcoholism

Background

Several studies have hypothesized that genes regulating the components of the serotonin system, including serotonin transporter (5-HTTLPR) and serotonin 1 B receptor (5-HT1B), may be associated with alcoholism, but their results are contradictory because of alcoholism’s heterogeneity. Therefore, we examined whether the 5-HTTLPR gene and 5-HT1B gene G861C polymorphism are susceptibility factors for a specific subtype of alcoholism, antisocial alcoholism in Han Chinese in Taiwan.

Methods

We recruited 273 Han Chinese male inmates with antisocial personality disorder (ASPD) [antisocial alcoholism (AS-ALC) group (n = 120) and antisocial non-alcoholism (AS-N-ALC) group (n = 153)] and 191 healthy male controls from the community. Genotyping was done using PCR-RFLP.

Results

There were no significant differences in the genotypic frequency of the 5-HT1B G861C polymorphism between the 3 groups. Although AS-ALC group members more frequently carried the 5-HTTLPR S/S, S/L_G, and L_G/L_G genotypes than controls, the difference became non-significant after controlling for the covarying effects of age. However, the 5-HTTLPR S/S, S/L_G, and L_G/L_G genotypes may have interacted with the 5-HT1B G861C C/C polymorphism and increased the risk of becoming antisocial alcoholism.

Conclusion

Our study suggests that neither the 5-HTTLPR gene nor the 5-HT1B G861C polymorphism alone is a risk factor for antisocial alcoholism in Taiwan’s Han Chinese population, but that the interaction between both genes may increase susceptibility to antisocial alcoholism.

The role of ALDH2 and ADH1B polymorphism in alcohol consumption and stroke in Han Chinese

The genes encoding the enzymes for metabolising alcohol dehydrogenase 1B (ADH1B) and aldehyde dehydrogenase 2 (ALDH2) -- exhibit genetic polymorphism and ethnic variations. Although the ALDH2*2 variant allele has been widely accepted as protecting against the development of alcoholism in Asians, the association of the ADH1B*2 variant allele with drinking behaviour remains inconclusive. The goal of this study was to determine whether the polymorphic ADH1B and ALDH2 genes are associated with stroke in male Han Chinese with high alcohol consumption. Sixty-five stroke patients with a history of heavy drinking (HDS) and 83 stroke patients without such a history (NHDS) were recruited for analysis of the ADH1B and ALDH2 genotypes from the stroke registry in the Tri-Service General Hospital, Taipei, Taiwan, between January 2000 and December 2001. The allelotypes of ADH1B and ALDH2 were determined using the polymerase chain reaction-restriction fragment length polymorphism method. The HDS patients (3 per cent) showed a significantly lower ALDH2*2 allele frequency than NHDS patients (27 per cent) (p < 0.001). After controlling for age, patients with HDS were associated with a significantly higher occurrence of cigarette smoking (p < 0.01) and liver dysfunction (p < 0.01). Multiple logistic regression analyses revealed that the ALDH2*2 variant allele was an independent variable exhibiting strong protection (odds ratio 0.072; 95 per cent confidence interval 0.02-0.26) against HDS after adjustment for hypertension, diabetes mellitus, smoking status and liver dysfunction. By contrast, allelic variations in ADH1B exerted no significant effect on HDS. The present study indicated that, unlike ALDH2*2, ADH1B*2 appears not to be a significant negative risk factor for high alcohol consumption in male Han Chinese with stroke.

The aldehyde dehydrogenase 2 gene is associated with heroin dependence

BACKGROUND

Determining the influences of genes involved in metabolizing dopamine and encoding dopamine receptors, such as the aldehyde dehydrogenase 2 (ALDH2) and dopamine D2 receptor/ankyrin repeat and kinase domain containing 1 (DRD2/ANKK1) genes, is critical for understanding addictive behavior. Therefore, we investigated the association between the ALDH2 and DRD2/ANKK1 Taq IA polymorphisms and heroin dependence.

METHODS

Heroin-dependent Han Chinese patients (250) and healthy controls (312) were recruited. ALDH2 and DRD2/ANKK1 Taq IA polymorphisms were genotyped.

RESULTS

The frequency of ALDH2*1/*2 and *2/*2 genotypes was significantly higher in heroin-dependent patients than in controls, but the frequency of DRD2 Taq IA genotypes was not significantly different. Logistic regression analysis showed no significant interaction between ALDH2 and DRD2 Taq IA genotypes in patients.

CONCLUSIONS

The ALDH2 polymorphism, but not the DRD2, was associated with heroin dependence.

Gender differences in the effects of ADH1B and ALDH2 polymorphisms on alcoholism

BACKGROUND

Gender differences are known to exist in the prevalence, characteristics, and course of alcohol dependence. Elucidating gender differences in the characteristics of alcohol dependence is important in gender-based medicine and may improve treatment outcomes. Many studies have shown that genetic factors are associated with the risk of alcohol dependence in both genders. Polymorphisms of alcohol dehydrogenase-1B (ADH1B) and aldehyde dehydrogenase-2 (ALDH2) are strong genetic determinants of alcohol dependence. This study aimed to clarify gender differences in the effects of ADH1B and ALDH2 polymorphism on the development of alcohol dependence.

METHODS

Subjects were 200 female alcoholics and 415 male alcoholics hospitalized in Kurihama Alcoholism Center. Clinical information and background data were obtained by chart review. ALDH2 and ADH1B genotyping was performed by the polymerase chain reaction-restriction fragment length polymorphism method.

RESULTS

The onset age of female alcoholics with inactive ALDH2 genotype was significantly lower than those with active ALDH2 genotype, but the onset age did not differ between the inactive and active ALDH2 group in male alcoholics. The difference in onset age between the ADH1B genotype groups did not reach significant levels. The prevalence of comorbid psychiatric disorders, including major depression, eating disorder, panic disorder, and borderline personality disorder, was significantly higher in female alcoholics with inactive ALDH2 or superactive ADH1B than in those with active ALDH2 or normal ADH1B.

CONCLUSIONS

ALDH2 polymorphism appears to have contrasting effects on the development of alcoholism in women and men. One possible reason for this gender difference may be the high prevalence of psychiatric comorbidities in female alcoholics with inactive ALDH2.

Genetics of alcohol dependence

Twin, family, and adoption studies have consistently shown that genetic factors play an important role in the pathogenesis of alcohol dependence. Numerous studies have aimed to identify genes that contribute to susceptibility to alcohol dependence. Whole-genome linkage studies have identified several chromosomal regions that are linked with alcohol dependence. Association studies have also identified genes associated with alcohol dependence. Alcohol-metabolizing enzymes, such as alcohol dehydrogenase-1B and aldehyde dehydrogenase-2, are the most well-established genes that have polymorphisms associated with the risk for alcohol dependence. Polymorphisms in gamma-aminobutyric acid receptor genes are also reported to be associated with alcohol dependence. The polymorphism of opioid receptor mu 1 gene is of interest because it alters the treatment effects of naltrexone. Several genes related to neural transmission have been reported to be associated with alcohol dependence, but results are inconsistent among studies. One reason for these inconsistent results is the great heterogeneity of alcohol dependence. Classifying alcohol dependence into homogeneous phenotypes is a good strategy to solve this problem. Recently, several genome-wide association studies have been reported. Genome-wide association studies enable hypothesis-free genome mapping of vulnerability-contributing genes and are expected to add data to identify genes associated with the susceptibility to alcohol dependence. Knowledge of the genetic basis of alcohol dependence is growing and leads to a better understanding of the biological mechanisms of addiction, which can help with strategies to prevent and treat this disease.

Neuropsychological functions in Han Chinese patients in Taiwan with bipolar II disorder comorbid and not comorbid with alcohol abuse/alcohol dependence disorder

OBJECTIVE

Studies exploring neuropsychological functions of bipolar disorder (BP) specifically include patients comorbid with alcohol abuse (AB), alcohol dependence (AD), or both (AB/AD). Contradictory assessments of neuropsychological impairment may be caused by not excluding the confounding effects of comorbid AB/AD. Most of the literature discusses BP without subtyping, which overlooks that BP-II may be a valid diagnosis different from BP-I. Because neuropsychological functions are involved in overall BP-II outcomes, we hypothesized that the neuropsychological functions of patients with BP-II comorbid with AD (BP(+AD)) are significantly different from and more impaired than those of patients with BP-II not comorbid with AD (BP(-AD)).

METHODS

Using DSM-IV criteria, the study included 69 patients with BP-II (19 with BP(+AD); 28 with BP(-AD)) and 22 healthy controls compared using a battery of neuropsychological tests that assessed memory, psychomotor speed, and certain aspects of frontal executive function. All BP-II patients were in an inter-episode period (a period of remission between states of mania, hypomania, and depression).

RESULTS

BP(+AD) patients had lower scores than did BP(-AD) patients and controls in verbal memory, visual memory, attention, psychomotor speed, and executive function. Working memory was poorer for BP(+AD) than BP(-AD) patients and for both BP groups than for controls.

CONCLUSIONS

BP(+AD) patients manifested wide neuropsychological dysfunctions, and BP(-AD) patients showed a reduction in working memory, which suggested that working memory might be related to a history of BP-II. Neuropsychological dysfunctions seemed more strongly associated with AB/AD than with BP-II in inter-episode periods.

MAOA interacts with the ALDH2 gene in anxiety-depression alcohol dependence

BACKGROUND

Alcohol dependence is usually comorbid with anxiety disorder, depressive disorder, or both; this comorbidity may increase drinking behavior. We previously hypothesized that anxiety-depressive alcohol dependence (ANX/DEP ALC) was a genetically specific subtype of alcohol dependence. ANX/DEP ALC may be related to dopamine and serotonin, which are catalyzed by monoamine oxidase A (MAOA) and acetaldehyde dehydrogenase 2 (ALDH2). The aim of this study was to determine whether the interaction between the MAOA and the ALDH2 genes is associated with ANX/DEP ALC.

METHODS

We recruited 383 Han Chinese men in Taiwan: 143 ANX/DEP ALC and 240 healthy controls. The diagnosis of ANX/DEP ALC (alcohol dependence with a past or current history of anxiety, depressive disorder, or both) was made using DSM-IV criteria. Genotypes of ALDH2 and MAOA-uVNTR (variable number of tandem repeat located upstream) were determined using PCR-RFLP.

RESULTS

The ALDH2, but not the MAOA-uVNTR, polymorphism was associated with ANX/DEP ALC. After stratifying the MAOA-uVNTR polymorphism, we found a stronger association between the ALDH2*1/*2 and *2/*2 genotypes and the controls in the MAOA-uVNTR 4-repeat subgroup. Logistic regression significantly associated the interaction between ALDH2 and MAOA variants with ANX/DEP ALC.

CONCLUSION

We conclude that the MAOA and ALDH2 genes interact in ANX/DEP ALC. Although the MAOA gene alone is not associated with ANX/DEP ALC, we hypothesize that different variants of MAOA-uVNTR polymorphisms modify the protective effects of the ALDH2*2 allele on ANX/DEP ALC in Han Chinese in Taiwan.

The relationship between serotonin receptor 1B polymorphisms A-161T and alcohol dependence

BACKGROUND

Several studies have suggested that the serotonin receptor 1B gene (5HT1B) may be important in the pathogenesis of alcohol dependence (alcoholism; ALC; AD). We examined whether 5HT1B gene A-161T polymorphisms (rs130058) are a susceptibility factor for total AD and subgroups of AD. We further explored correlation of this 5HT1B gene variant between anxiety-depression alcoholism (ANX/DEP ALC) and antisocial alcoholism (antisocial ALC) subgroups because of the high comorbidity of anxiety-depression, antisocial personality disorder, and AD.

METHODS

We recruited 522 Han Chinese in Taiwan for this study: 322 AD patients and 200 controls. The patient group was recruited primarily from medical teaching hospitals; patients with antisocial alcoholism were recruited from Taiwanese prisons. Individuals with AD were classified into 3 homogeneous clinical subgroups -- pure alcoholism (pure ALC), ANX/DEP ALC, and antisocial ALC -- using DSM-IV diagnosis. The 5HT1B gene A-161T polymorphism was determined using PCR-RFLP.

RESULTS

No significant differences in genotypic and allelic frequencies were found between controls and the total AD group or between controls and the 3 AD subgroups. However, there were significant differences in the 5HT1B gene A-161T polymorphism at both the genotype and allelic levels between the ANX/DEP ALC and antisocial ALC subgroups.

CONCLUSIONS

This study suggests that the 5HT1B gene A-161T polymorphism alone is not a risk factor for increasing susceptibility to either AD or its subtypes. However, 5HT1B gene A-161T polymorphisms might be one of the common genetic factors between the ANX/DEP ALC and antisocial ALC subgroups.

MAOA-uVNTR polymorphism may modify the protective effect of ALDH2 gene against alcohol dependence in antisocial personality disorder

BACKGROUND

Antisocial alcoholism is related to dopamine and serotonin which are catalyzed by monoamine oxidase A (MAOA) and acetaldehyde dehydrogenase 2 (ALDH2). The objective of this study is to determine whether the interaction between the MAOA and the ALDH2 genes is associated with subjects with antisocial personality disorder (ASPD) having alcoholism.

METHODS

A total of 294 Han Chinese men in Taiwan including 132 ASPD with alcoholism (Antisocial ALC) and 162 without alcoholism (Antisocial Non-ALC) were recruited in this study. Alcohol dependence and ASPD were diagnosed according to DSM-IV criteria. Genotypes of ALDH2 and MAOA-uVNTR were determined using PCR-RFLP.

RESULTS

A significant difference of ALDH2 polymorphisms (p = 3.39E-05), but not of MAOA, was found among the 2 study groups. However, only after the stratification of the MAOA-uVNTR (variable number of tandem repeat located upstream) 3-repeat, a significant association between Antisocial Non-ALC and ALDH2*1/*2 or *2/*2 genotypes was shown (p = 1.46E-05; odds ratio = 3.913); whereas stratification of MAOA-uVNTR 4-repeat revealed no association. Multiple logistic regression analysis further revealed significant interaction of MAOA and ALDH2 gene in antisocial ALC (odds ratio = 2.927; p = 0.032).

CONCLUSION

The possible interaction of MAOA and ALDH2 gene is associated with Antisocial ALC in Han Chinese males in Taiwan. However, the protective effects of the ALDH2*2 allele against alcoholism might disappear in subjects with ASPD and carrying MAOA-uVNTR 4-repeat allele in the Han Chinese male population.

The association between DRD2/ANKK1, 5-HTTLPR gene, and specific personality trait on antisocial alcoholism among Han Chinese in Taiwan

Cloninger suggested that type II alcoholism was associated with higher novelty seeking and less harm avoidance behaviors, which was similar to antisocial alcoholism. Most previous studies have failed to recruit subjects that have antisocial personality disorder without alcoholism due to the high coexisting likelihood of having antisocial personality disorder with alcoholism in the majority of the examined populations. Thus, recruitment of individuals with antisocial non-alcoholism (antisocial personality disorder) served as an important control group in examining Cloninger's hypothesis. Due to the documented protective effects against alcoholism of ALDH2*1/*2 or *2/*2 genotype among the Han Chinese population, we recruited antisocial non-alcoholics from the Han Chinese population in Taiwan to verify Cloninger's hypotheses. A total of 127 Han Chinese subjects were recruited who met the diagnosis of antisocial alcoholism (n = 43) or antisocial non-alcoholism (n = 84). We found that the antisocial alcoholism group scored higher on the novelty seeking behavior than did the antisocial non-alcoholism group (t = 2.61, P = 0.01), but no difference was observed on the harm avoidance dimension between these two groups (t = 0.15, P = 0.88). In the novelty seeking scores, after stratification of DRD2 TaqI A genotypes, only a significant difference in 5-HTTLPR polymorphisms between antisocial alcoholics and antisocial non-alcoholics was found, indicating an interaction between DRD2 TaqI A1+ (include A1/A1 or A1/A2) and 5-HTTLPR S/S genotype (t = 2.75, P = 0.01) However, no significant difference was found in the harm avoidance personality trait between these two groups of Han Chinese in Taiwan.

Specific personality traits and dopamine, serotonin genes in anxiety-depressive alcoholism among Han Chinese in Taiwan

BACKGROUND

Cloninger [Cloninger CR. 1987. Neurogenetic adaptive mechanisms in alcoholism. Science 236: 410-416.] had proposed a psychobiological model suggesting that three main personality dimensions distinguish the alcoholism into two subtypes (type I and type II). However, the classification was equivocal for clinical diagnosis. Recently, anxiety-depressive alcohol dependence (ANX/DEP ALC) has been posited as a genetically specific subtype of alcoholism. Its clinical characteristics were similar to individuals with type I alcoholism [Cloninger, C.R. 1987. Neurogenetic adaptive mechanisms in alcoholism. Science 236: 410-6.] such as having a high comorbidity with mood disorder, late-onset and more anxious/depressed traits. We attempted to investigate whether the dopamine D2 receptor (DRD2) and the serotonin transporter promoter region (5-HTTLPR) genes were involved in Novelty Seeking (NS) and Harm Avoidance (HA) of ANX/DEP ALC.

METHODS

We recruited 46 pure alcohol dependents (Pure ALC) and 87 anxiety-depression alcohol dependents (ANX/DEP ALC). All participants were diagnosed by DSM-IV criteria, genotyped by the PCR method and assessed with Tridimensional Personality Questionnaire (TPQ).

RESULTS

Both NS and HA were high in ANX/DEP ALC (p = 0.021; p = 0.001, respectively). The association between NS and ANX/DEP ALC only existed in subjects with DRD2 TaqI A1(+) allele (A1/A1 or A1/A2 genotypes) (p = 0.004) and in those with S/S genotype of 5-HTTLPR (p = 0.005). With the stratification of DRD2 TaqI A1(+) allele, high NS of ANX/DEP ALC existed only in carriers of 5-HTTLPR S/S genotype (p=0.001). Moreover, ANX/DEP ALC was related to high HA only in samples carrying 5-HTTLPR S/L or L/L genotype (p = 0.02).

CONCLUSIONS

These findings provided the empirical genetic characterization of the specific personality traits in ANX/DEP ALC among Han Chinese population in Taiwan.

Possible interaction between MAOA and DRD2 genes associated with antisocial alcoholism among Han Chinese men in Taiwan

Both monoamine oxidase A (MAOA) and dopamine D(2) receptor (DRD2) genes have been considered as candidate genes for antisocial personality disorder with alcoholism (Antisocial ALC) [Parsian, A., 1999. Sequence analysis of exon 8 of MAO-A gene in alcoholics with antisocial personality and normal controls. Genomics. 45, 290-295.; Samochowiec, J., Lesch, K.P., Rottmann, M., Smolka, M., Syagailo, Y.V., Okladnova, O., Rommelspacher, H., Winterer, G., Schmidt, L.G., Sander, T., 1999. Association of a regulatory polymorphism in the promoter region of the monoamine oxidase A gene with antisocial alcoholism. Psychiatry. Res. 86, 67-72.; Schmidt, L.vG., Sander, T., Kuhn, S., Smolka, M., Rommelspacher, H., Samochowiec, J., Lesch, K.P., 2000. Different allele distribution of a regulatory MAO-A gene promotor polymorphism in antisocial and anxious-depressive alcoholics. J. Neural .Transm. 107, 681-689.]. However, the association between alcoholism and MAOA or DRD2 gene has not been universally accepted [Lee, J.F., Lu, R.B., Ko, H.C., Chang, F.M., Yin, S.J., Pakstis, A.J., Kidd, K.K., 1999. No association between DRD(2) locus and alcoholism after controlling the ADH and ALDH genotypes in Chinese Han population. Alcohol. Clin. Exp. Res. 23, 592-599.; Lu, R.B., Lin, W.W., Lee, J.F., Ko, H.C., Shih, J.C., 2003. Neither antisocial personality disorder nor antisocial alcoholism association with MAOA gene among Han Chinese males in Taiwan. Alcohol. Clin. Exp. Res. 27, 889-893.]. Since dopamine is metabolized to 3,4-dihydroxyphenyl-acetaldehyde (DOPAL) via monoamine oxidase (MAO) [Westerink, B.H., de Vries, J.B., 1985. On the origin of dopamine and its metabolite in predominantly noradrenergic innervated brain areas. Brain. Res. 330, 164-166.], the interaction between MAOA and DRD2 genes might be related to Antisocial ALC. The present study aimed to determine whether Antisocial ALC might be associated with the possible interactions of DRD2 gene with MAOA gene. Of the 231 Han Chinese subjects who were recruited for the study, 73 participants were diagnosed with Antisocial ALC and 158 subjects were diagnosed with antisocial personality disorder without alcoholism (Antisocial Non-ALC). The DRD2 TaqI A and MAOA-uVNTR (variable number of tandem repeat located upstream) polymorphisms were not found to be associated with Antisocial ALC. However, an association between DRD2 TaqI A polymorphisms and Antisocial ALC was shown only after stratification for the MAOA-uVNTR 4-repeat polymorphism. Additionally, after multiple logistic regressions, we found that, under stratification of MAOA-uVNTR 4-repeat polymorphism and in comparison with the DRD2 A1/A1 genotype as a reference group, the DRD2 A1/A2 genotype has a possible protective effect against alcoholism in individuals with antisocial personality disorder (ASPD). We concluded that the possible interactions between MAOA-uVNTR polymorphism and DRD2 TaqI A polymorphism might be related to Antisocial ALC among Han Chinese men in Taiwan.

Interactive effects of lifetime alcohol consumption and alcohol and aldehyde dehydrogenase polymorphisms on esophageal cancer risks

In our previous study, we found that polymorphisms of alcohol and aldehyde dehydrogenase (ADH1B and ALDH2) are important risks for esophageal squamous cell carcinoma in a Taiwanese population. In this study, we increased the sample size to investigate the modifying effect of lifetime alcohol consumption on the association between ADH1B and ALDH2 genotypes and the risks of esophageal cancer. A multicenter hospital-based case-control study was conducted between August 2000 and June 2004. Three hundred and thirty newly-diagnosed esophageal squamous cell carcinoma patients and 592 controls were recruited from National Taiwan University Hospital in Taipei and Kaohsiung Veterans General Hospital and Kaohsiung Medical University Hospital in Kaohsiung, Taiwan. Controls were matched to the case patients by gender and age within 4 years (case:control = 1:1-4). Polymorphisms of ADH1B and ALDH2 were genotyped by the method of PCR-RFLP. Individuals with ADH1B*1/*1 genotype had a 3.99-fold risk (95% CI = 2.13-7.48) of developing esophageal cancer, compared with those with ADH1B*2/*2 genotype, after adjusted for appropriate covariates. Individuals with ALDH2*1/*2 and ALDH2*2/*2 had 4.99-fold risk (95% CI = 3.11-7.99) and 4.24-fold risk (95% CI = 1.52-11.84), respectively, of developing esophageal cancer, compared with those with ALDH2*1/*1, after adjusted for appropriate covariates. We also found a modifying effect of lifetime alcoholic consumption on the association between genotypes of ADH1B and ALDH2 on esophageal cancer risk. These results suggest that ADH1B and ALDH2 polymorphisms play a pivotal role on esophageal cancer and that the effect of these polymorphisms was modified by the amount of alcohol consumed.