Novel allelic variants in the human serotonin transporter gene linked polymorphism (5-HTTLPR) among depressed patients with suicide attempt

A polymorphism in the serotonin transporter gene (5-HTTLPR) is being extensively studied for association with suicidal behavior. A new allelic variant within the 5-HTTLPR polymorphism was described but it has not been thoroughly analyzed in the recent literature. The SNP functional analysis demonstrated that the A variant of the L allele (L_A) produces high levels of mRNA and that the G variant (L_G) is equivalent to the S allele. Our aims were to compare the frequency of 5-HTTLPR alleles in 94 depressed patients who attempted suicide compared to 94 controls free of psychiatric disorder, including the embedded SNP rs25531. Using the biallelic classification, our sample contained 62 (33%) LL, 76 (40.4%) LS, and 50 (26.6%) SS individuals. Using the functional classification system, our sample contained 43 (22.5%) L’L’, 84 (44.7%) L'S’, and 61 (32.4%) S'S’ individuals, with no significant differences between cases and controls in genotypic tests in either biallelic (χ² = 2.543; df = 2; p = 0.280) and functional models (χ² = 2.995; df = 2; p = 0.228). The minor allele frequency (MAF) – the S allele – did not show any distributional difference between cases and controls using biallelic classification system 0.51 vs. 0.43, (OR = 1.41; CI95% 0.94 to 2.12; p = 0.121). Also the S’ allele of the functional classification system did not show any distributional difference between the two groups 0.59. vs. 0.51 (OR = 1.35; CI95% 0.90 to 2.03; p = 0.178). This study provided the possibility of a re-analysis of novell 5-HTTLPR functional variants identified within L allele that alters its mRNA production and thus changes its functionality. We could not find any association between both biallelic and functional 5-HTTLPR in depressed patients with suicide attempt, being the small sample size an important limitation for these results. In conclusion, we can suggest that despite the several studies in this issue, the exact effect and role of 5-HTTLPR in genetics of suicide is still unclear and should be better investigated for future studies.     

Variations in the serotonin-transporter gene are associated with attention bias patterns to positive and negative emotion faces

Both attention biases to threat and a serotonin-transporter gene polymorphism (5-HTTLPR) have been linked to heightened neural activation to threat and the emergence of anxiety. The short allele of 5-HTTLPR may act via its effect on neurotransmitter availability, while attention biases shape broad patterns of cognitive processing. We examined individual differences in attention bias to emotion faces as a function of 5-HTTLPR genotype. Adolescents (N = 117) were classified for presumed SLC6A4 expression based on 5-HTTLPR—low (SS, SL_G, or L_GL_G), intermediate (SL_A or L_AL_G), or high (L_AL_A). Participants completed the dot-probe task, measuring attention biases toward or away from angry and happy faces. Biases for angry faces increased with the genotype-predicted neurotransmission levels (low > intermediate > high). The reverse pattern was evident for happy faces. The data indicate a linear relation between 5-HTTLPR allelic status and attention biases to emotion, demonstrating a genetic mechanism for biased attention using ecologically valid stimuli that target socioemotional adaptation.     

Investigation of the dopamine D5 receptor gene (DRD5) in adult attention deficit hyperactivity disorder

Several lines of evidence from neuroimaging, pharmacology and genetics support the involvement of the dopaminergic system in the etiology of Attention Deficit Hyperactivity Disorder (ADHD). Previous candidate gene studies have investigated the association between a dinucleotide (CA)_n repeat polymorphism, located 18.5 kb from the start codon of the DRD5 gene, and ADHD. Association between the 148 bp allele and ADHD has been reported in some studies, however replication of the finding has not been consistent. We tested for an association between the (CA)_n repeat and adult ADHD in a sample comprised of 119 families with adult ADHD probands and 88 unrelated adult ADHD cases with a corresponding number of controls matched for age, ethnicity and sex. In the family sample we found a non-significant trend for association between the 148 bp allele and ADHD (Z = 1.91, p = 0.055). An excess of non-transmissions was detected for the 150 and 152 bp alleles (Z = −2.26, p = 0.023; Z = −2.20, p = 0.028). Quantitative analysis performed using the Brown Attention Deficit Disorder Scale (BADDS) showed association between the 150 bp allele and lower total score (p = 0.011), and lower effort (p = 0.008), activation (p = 0.008) and attention (p = 0.01) cluster scores. We did not replicate association findings in the case–control group, likely due to the lack of statistical power of this sample. Our findings add to the literature suggesting DRD5 (CA)_n repeat has a modest effect in modulating susceptibility to adult ADHD but further studies are required.     

Serotonin transporter polymorphic region 5-HTTLPR modulates risk for Parkinson's disease

The association between the serotonin transporter gene (SLC6A4) polymorphisms, that is, 5-HTTLPR and rs25531, and Parkinson's disease (PD) remains to be further defined. We investigated this relationship in a Chinese cohort that comprised 504 PD patients and 504 controls. A total of 8 haplotypes and 14 genotypes of SLC6A4 were found in this population including a new variant of 5-HTTLPR, that is, 20_G. Our results presented that 5-HTTLPR was associated with an aggravated risk for PD (p = 0.005). The rs25531 alone is not associated with PD susceptibility. However, in a sub-classification based on the impact of 5-HTTLPR and rs25531 on 5-HTT expression, we observed a significant difference in 5-HTT expressing distribution in the cohort, accompanied by an apparently lower level of 5-HTT high expressing group, that is, the L_AL_A genotype, in the PD patients. Taken together, our data provide novel insight in support that the SLC6A4 polymorphisms, particularly 5-HTTLPR, and the serotonergic system are associated with PD etiology.     

Male specific association between the 5-HTR6 gene 267C/T SNP and suicide in the Portuguese population

Serotonergic system dysfunction has been implicated in the etiology of suicide. A large number of genetic studies have focused on the potential involvement of genes coding for components of serotonergic system in suicidal behavior. However, other genes belonging to this system remain to be investigated or have been poorly studied, as is the case of the 5-HT6 receptor (5-HTR6) gene. In this study, we investigated the potential association between the 5-HTR6 gene 267C/T SNP and suicide in a Portuguese population. Blood samples were collected from 179 suicide victims and 189 controls. Genotypes for the 5-HTR6 gene 267C/T SNP were obtained with the restriction enzyme Rsa I. A tendency was found for genotype association between this polymorphism and suicide, but the differences were not statistically significant (χ² = 5.374, df = 2, p = 0.068). However, a gender-specific association was detected when comparing the genotype distribution between male suicide victims and male controls (χ² = 6.988, df = 2, p = 0.030), suggesting that this SNP might have a role in the etiology of suicide in male subjects in the Portuguese population.     

The 5‐HT2A receptor gene 102T/C polymorphism is associated with suicidal behavior in depressed patients

Several lines of evidence suggest that genetic factors constitute an important determinant of suicidal behavior. A significant association between the 5‐HT_2A‐C allele and suicidality has recently been reported. The aim of this study was to investigate whether the proposed association between 5‐HT_2A‐102T/C polymorphism and suicidality could be replicated in a larger and independent sample of Spanish patients with major depression. The 102T/C polymorphism of the 5‐HT_2A receptor gene was analyzed in 159 patients with major depression (DSM‐IV criteria) and 164 unrelated and healthy controls using a case control design. All individuals were subjects of Spanish origin. Significant differences in allele (chi‐square = 4.13, df = 1, P = 0.04) and genotype (chi‐square = 6.19, df = 2, P = 0.04) distributions were found between non–suicide attempters and suicide attempters. Moreover, those patients carrying 5‐HT_2A‐C allele had more than five times the risk for attempting suicide than noncarriers (OR = 5.50, 95% CI = 1.18–35.20, P = 0.01). Our results replicate the proposed association between 5HT_2A‐C allele and suicidality in major depression. Moreover, no overall associations are detected when patients with major depression and controls are compared for 102T/C frequencies, suggesting that the increased risk for suicidality conferred by 5‐HT_2A‐C allele is primarily associated with suicidal behavior and not with the diagnosis of major depression itself. © 2001 Wiley‐Liss, Inc.     

SNP/haplotype associations of CCR2 and CCR5 genes with severity of chagasic cardiomyopathy

Background

Chronic inflammation plays a major role in the tissue injury seen in the chronic chagasic cardiomyopathy. The CCR2 and CCR5 chemokine receptors are involved with the type of cellular infiltrate present in cardiac tissue and CCR5-gene variants were previously associated with this pathology.

Methods and results

This is a replication study in an independent cohort with larger sample size. Nine SNPs of CCR5 and CCR2 were typified to confirm the association previously found with Chagas disease. Evidence of association with severity was found for the A allele of rs1799864 of CCR2 (p_ad = 0.02; OR = 1.91, 95% CI = 1.10–3.30), the T allele of the rs1800024 of CCR5 (p_ad = 0.01; OR = 1.95, 95% CI = 1.13–3.38), and the HHF^∗2 haplotype (p = 0.03, OR = 1.65, 95% CI = 1.03–2.65). These results were replicated in the study combined with previous data. In this analysis it was replicated the allele T of rs2734648 (p_ad = 0.009, OR = 0.52, 95% CI = 0.32–0.85) with protection. In addition, the allele G of rs1800023 (p_ad = 0.043, OR = 0.61, 95% CI = 0.38–0.98), and the HHC haplotype (p = 0.004, OR = 0.62, 95% CI = 0.44–0.86) were also associated with protection. In contrast, the allele A of rs1799864 of CCR2 (p_ad = 0.009; OR = 1.90, 95% CI = 1.17–3.08); and the allele T of rs1800024 of CCR5 (p_ad = 0.005, OR = 1.98, 95% CI = 1.22–3.23) were associated with greater severity. No evidence of association between symptomatic and asymptomatic patients was observed.

Conclusions

These results confirm that variants of CCR5 and CCR2 genes and their haplotypes are associated with the severity but not with susceptibility to develop chagasic cardiomyopathy.     

Association study between a functional polymorphism of FK506-binding protein 51 (FKBP5) gene and personality traits in healthy subjects

Previous studies have shown that the function of hypothalamic-pituitary-adrenal (HPA) axis is involved in the characterization of personality traits. FK506-binding protein 51 (FKBP51 or FKBP5) is a co-chaperone of heat-shock protein 90, and plays an important role in the negative feedback regulation of HPA axis function. It has been reported that a C/T single nucleotide polymorphism in the intron 2 of FKBP5 gene (rs1360780) affects FKBP5 protein levels and cortisol response to dexamethasone and psychological stress tests. Therefore, it is hypothesized that the FKBP5 polymorphism affects personality traits. In the present study, we studied the association between this polymorphism and personality traits in 826 Japanese healthy subjects. Personality traits were assessed by the Temperament and Character Inventory (TCI), and the FKBP5 genotype was detected by a real-time PCR and cycling probe technology for SNP typing. In total subjects, the group with the T allele predictive of impaired negative feedback regulation of the HPA axis had higher scores of harm avoidance (HA) (p = 0.043) and lower scores of cooperativeness (CO) (p = 0.019) compared to that without the T allele. The T allele was associated with higher scores of HA in females (p = 0.020) and lower scores of CO in males (p = 0.015). The present study thus suggests that the FKBP5 polymorphism affects HA and CO in healthy subjects, with gender specificity.     

Emotional management and 5-HT2A receptor gene variance in patients with schizophrenia

Individuals with schizophrenia exhibit impaired social cognitive functions, particularly emotion management. Emotion management may be partially regulated by the serotoninergic system; the −1438 A/G polymorphism in the promoter region of the 5-HT2A gene can modulate 5-HT2A activity and is linked to certain emotional traits and anger- and aggression-related behaviors. The current study aimed to investigate whether this 5-HT2A genetic variance is associated with social cognitive function, particularly the management of emotions. One hundred and fifteen patients with chronic schizophrenia were stabilized with an optimal-dose of antipsychotic treatment. All were genotyped for the −1438 A/G polymorphism and assessed with symptom rating scales, neurocognitive instruments, and the “Managing Emotions” section of Mayer-Salovey-Caruso Emotional Intelligence Test (MSCEIT). Multiple regression showed that patients with the A/G genotype performed better than those with G/G in managing emotion (p = 0.018) but did not differ from those with the A/A genotype. Regarding the two subtasks of the Managing Emotions section, the A/G heterozygotes also performed better than the G/G homozygotes in the emotion management (p = 0.026) and emotional relations (p = 0.027) subtasks. The results suggest that variability in the 5-HT2A gene may influence emotion management in patients with schizophrenia.     

Different MAPT haplotypes are associated with Parkinson's disease and progressive supranuclear palsy

The H1 MAPT haplotype in the 17q21 chromosomal region has been associated with several neurodegenerative diseases. Some reports have suggested that there is an association between genetic variants within the H1 haplotype with Parkinson's disease (PD), progressive supranuclear palsy (PSP) and corticobasal degeneration (CBD). Here we report a genetic association study using seven SNPs located along the 17q21 region, in PD patients and controls. In addition, we compared these results with a dataset of previously published PSP/CBD patients from the same population. Our results show that the H1-rs242557^G allele sub-haplotype is increased in PD (p = 0.005), while the H1-rs242557^A allele sub-haplotype is increased in PSP/CBD (p = 0.0002), comparing to controls. The rs242557 polymorphism could act modulating the phenotypic expressivity of the H1 risk on these parkinsonisms. The location of this polymorphism in the 5′ regulatory region of MAPT gene suggests the presence of a functional mechanism involved in the variation of MAPT expression levels.     

Effect of chronic activation of 5-HT3 receptors on 5-HT3, 5-HT(1A) and 5-HT(2A) receptors functional activity and expression of key genes of the brain serotonin system

The dopamine D3 receptor gene (DRD3) is considered being one of the candidate genes contributing to the development of tardive dyskinesia (TD). In a recent meta-analysis with mixed ethnicities, only a barely positive association was found between the functional DRD3 Ser9Gly polymorphism and TD in patients with schizophrenia (OR = 1.17; 95% CI: 1.01-1.37; p = 0.041). To further evaluate the controversial association between the polymorphism and TD using only Japanese subjects, we tested the association in a case-control design. We also conducted a meta-analysis including 8 studies with 3 East Asian populations (Japanese, Chinese, and Korean). In our Japanese case-control sample (43 with TD/157 without TD), we found no association between the DRD3 Ser9Gly polymorphism in schizophrenia and TD (genotype: p = 0.92; allele: p = 1.00). Furthermore, no significant difference in the mean AIMS score among the three genotypic groups was observed in our sample. The meta-analysis comprising 1291 East Asian subjects also showed no association between the polymorphism and TD; the Mantel-Haenszel pooled OR for TD among carriers of the DRD3 Ser9Gly of the eight Asian studies was 0.94 (95% CI: 0.78-1.12). Overall, our results suggest that the DRD3 Ser9Gly polymorphism may not confer susceptibility to TD in East Asian populations. Given that the Ser9Gly variant may play a putative role in the DRD3 function, further studies on the DRD3 are warranted.     

Association between functional Fc receptor-like 3 (FCRL3) −169 C/T polymorphism and susceptibility to seropositive rheumatoid arthritis in Asians: A meta-analysis

Objective

The aim of this study was to determine whether the functional Fc receptor like-3 (FCRL3) −169 C/T polymorphism confers susceptibility to rheumatoid arthritis (RA).

Methods

A meta-analysis was conducted on the associations between the FCRL3 −169 C/T polymorphism and RA.

Results

A total of 17 comparison studies including 11,170 patients and 11,142 controls were considered in the meta-analysis. The meta-analysis showed no association between RA and the FCRL3 −169 C allele in study subjects (OR = 1.046, 95% CI = 0.997–1.098, p = 0.068). Stratification by ethnicity indicated an association between the FCRL3 −169 C allele and RA in Asians (OR = 1.101, 95% CI = 1.035–1.174, p = 0.002), but not in Europeans. Stratification of patients according to the presence of rheumatoid factor (RF) revealed a different significant association between the C allele and RA in RF-positive and RF-negative RA patients. Stratification by ethnicity indicated an association between the FCRL3 −169 C allele and RF-positive RA in Asians (OR = 1.093, 95% CI = 1.004–1.189, p = 0.040), but not in Europeans.

Conclusions

This meta-analysis demonstrates that the FCRL3 −169 C/T polymorphism may confer susceptibility to seropositive RA in Asians.     

Panic disorder and serotonergic genes (SLC6A4, HTR1A and HTR2A): Association and interaction with childhood trauma and parenting

Objective

The aim of this study is to evaluate the association between HTR1A, HTR2A and the 5-HTTLPR in panic disorder (PD) patients and controls. In addition, this study also aims to evaluate the interaction between these genes and two environmental factors previously associated with PD: childhood trauma and parental bonding.

Methods

This is a case–control candidate gene association study (107 PD patients and 125 controls). Genes were analyzed using a gene-based test in PLINK followed by single marker association tests and haplotype test only for genes that reached experiment-wide significance in the gene-based test in order to minimize multiple testing. Logistic regression was used to test the relationships between genotype in the additive model, trauma, optimal paternal parenting and optimal maternal parenting and their interactions.

Results

Only HTR1A was associated with PD in gene-based test after correction for multiple tests (p_corrected = 0.027) and one HTR1A haplotype comprising four SNPs was associated with PD (p_corrected = 0.032). In the interaction analysis, no significant gene–environment interaction was found with the genes evaluated.

Conclusion

This study reinforces the association between HTR1A and PD. No major evidence of gene–environment interaction in PD with parenting or trauma was found. Further studies are necessary in order to confirm these findings.     

Support for the involvement of the ERBB4 gene in schizophrenia: A genetic association analysis

Cellular, animal and human studies support the involvement of aberrant NRG–ErbB signaling in the pathogenesis of schizophrenia. The aim of the present study was to examine whether genetic variation in the human ERBB4 gene is associated with susceptibility to schizophrenia. Two hundred and twenty-seven unrelated chronic inpatients with schizophrenia were enrolled in the study, and the genetic variation in the polymorphisms of the ERBB4 gene in the patients was compared with that of the control group, which consisted of 223 subjects free of psychiatric illness. The results showed that one coding-synonymous polymorphism (rs3748962, Val1065Val) was in genotypic (p = 0.0027) and allelic (p = 0.0007) association with schizophrenia. In comparison with subjects of the rs3748962-TT type, those of the rs3748962-CT and rs3748962-CC types were at 1.74- and 2.64-fold greater risk of schizophrenia (CT vs. TT: OR = 1.71 (95% CI = 1.15–2.53), p = 0.0014; CC vs. TT: OR = 2.64 (95% CI = 1.37–5.23), p = 0.0047), which supports the hypothesis of an additive model of transmission (p = 0.0006). Furthermore, the frequency of haplotype ATC of rs3791709–rs2289086–rs3748962 was found to be significantly higher in the patients with schizophrenia than in the controls (case vs. control = 36.0% vs. 24.4%, permutation p-value = 0.0002). The findings support the involvement of the ERBB4 gene in schizophrenia in Han Chinese.     

Toll-like receptor 4 gene Asp299Gly polymorphism in myocardial infarction: A meta-analysis of 15,148 subjects

It remains controversial regarding the association between toll-like receptor 4 (TLR4) gene Asp299Gly (+896 A/G) polymorphism and myocardial infarction (MI) risk. Thus, a large-scale meta-analysis evaluating the potential association between this gene variant and MI risk is required. PubMed, Embase, Web of Science, CBMdisc, CNKI, and Google Scholar were searched until February 6, 2013. All the statistical tests were performed using Stata 11.0. Nine articles involving 10 studies were included in the final meta-analysis, covering a total of 8299 MI cases and 6849 controls. Overall, no significant association was found between the TLR4 gene Asp299Gly polymorphism and MI risk (G allele vs. A allele: OR = 0.95, 95% CI = 0.74–1.22, p = 0.71; G/G vs. A/A: OR = 1.03, 95% CI = 0.54–1.98, p = 0.93; G/G vs. A/G + A/A: OR = 1.05, 95% CI = 0.55–2.03, p = 0.87; G/G + A/G vs. A/A: OR = 0.92, 95% CI = 0.75–1.13, p = 0.42). In the subgroup analysis based on source of controls, there was also lack of evidence for significant association between the TLR4 gene Asp299Gly polymorphism and MI risk. In summary, the present meta-analysis indicated that the TLR4 gene Asp299Gly polymorphism was not associated with MI risk.     

Lack of association between the functional c-kit rs6554199 polymorphism and achalasia in a Spanish population

A functional polymorphism (rs6554199) located in the c-kit gene was associated with achalasia in a Turkish cohort. Our aim was to replicate this result in a large cohort of Spanish patients and controls. A case-control study was performed with 282 Spanish white unrelated patients and 687 healthy controls. All were genotyped for SNP rs6554199 using a TaqMan Assay. No association was found in our study (T allele frequency in patients and controls: 47.3% vs. 49.4%; OR = 0.92, p = 0.41). The finding that the T allele of the c-kit rs6554199 polymorphism could be associated with achalasia as reported in a Turkish population could not be replicated in a Spanish cohort. Although ethnic differences might explain these data, the sample size that compromised the statistical power in the Turkish cohort and is higher in our study, led us to suggest that the reported association seems to be a false positive.     

Association between CTLA-4 polymorphisms and susceptibility to Celiac disease: A meta-analysis

Objective

The study explored whether cytotoxic T lymphocyte antigen-4 (CTLA-4) polymorphisms confer susceptibility to Celiac disease (CD).

Methods

A meta-analysis was conducted on the associations between the CTLA-4 CT60 A/G, +49 A/G, −318 C/T polymorphisms and CD using allele contrast, a recessive model, a dominant model, and homozygote contrast.

Results

Thirteen separate comparison studies were considered in the meta-analysis consisting of 5072 patients with CD and 13,462 controls. All subjects were Europeans. Meta-analysis of the CTLA-4 CT60 A/G polymorphism showed an association between CD and the CTLA-4 CT60 G allele in all subjects [Odds ratio (OR) = 1.160, 95% Confidence interval (CI) = 1.104–1.219, p < 1.0 × 10⁻⁹). Meta-analysis using the recessive model also revealed an association between CD and the CTLA-4CT60 GG genotype (OR = 1.331, 95% CI = 1.093–1.620, p = 0.004). Furthermore, analyses using the dominant model and homozygote contrast showed the same pattern as that shown by the CTLA-4CT60 G allele. Meta-analysis of the CTLA-4 +49 A/G polymorphism showed no association between CD and the CTLA-4 +49 G allele in all subjects (OR = 0.992, 95% CI = 0.872–1.129, p = 0.907). Meta-analysis using the recessive, dominant model, and homozygote contrast showed the same pattern as that shown by the CTLA-4 +49 Gallele. Meta-analysis of the CTLA-4 −318 C/T polymorphism showed no association between CD and the CTLA-4 −318 T allele in all subjects (OR = 1.018, 95% CI = 0.813–1.275, p = 0.877).

Conclusions

The CTLA-4 CT60 A/G polymorphism was associated with CD susceptibility, but no association was found between CTLA-4 +49 A/G and −318 C/T polymorphisms and CD in Europeans.     

Association of the (TAAAA)n repeat polymorphism of SHBG gene with the age at menopause in Greek postmenopausal women

Objective

To assess the potential association of the pentanucleotide (TAAAA)n repeat polymorphism in the promoter of SHBG gene with the age at menopause in a Greek female population.

Study design

Cross-sectional study. Two hundred and ten postmenopausal women aged 46–63 years were enrolled. The age at the last menstrual period and anthropometric parameters were recorded in all participants. Blood sampling for genotyping of the (TAAAA)n polymorphism of SHBG gene was performed.

Main outcome measure(s)

Frequency and association of the (TAAAA)_n alleles with age at menopause.

Results

The alleles with seven and eight TAAAA repeats were associated with the age at menopause. The age at menopause was higher in carriers than in non-carriers of the (TAAAA)₇ allele (50.2 ± 3.1 years vs. 48.0 ± 4.8 years, p = 0.026). Furthermore, the age at menopause was lower in women carrying the (TAAAA)₈ allele (47.5 ± 4.8 years) than in women not carrying this allele (48.8 ± 4.4 years, p = 0.048).

Conclusions

The (TAAAA)₇ and (TAAAA)₈ alleles of the SHBG (TAAAA)_n polymorphism may contribute to variation in the timing of natural menopause in postmenopausal women of Northwestern Greece.