Association of intron 1 variants of the dopamine transporter gene with schizophrenia

The dopamine transporter (DAT1) gene has been implicated in the pathogenesis of many neuropsychiatric disorders, including schizophrenia. The present study aimed to investigate association of the DAT1 gene polymorphisms with schizophrenia in a Han Chinese population. Two single nucleotide polymorphisms (SNPs) in the DAT1 gene (rs2975223 and rs2455391) were tested in 368 patients with schizophrenia and 420 healthy controls, of whom 293 patients underwent an assessment of psychotic symptoms through the positive and negative syndrome scale (PANSS). The chi-square test (χ²) showed disease association for rs2455391 (corrected p = 0.023 for allelic association and p = 0.034 for genotypic association, respectively). The rs2975223(G)–rs2455391(C) haplotype was associated with increased risk of the illness (p = 0.0012, OR = 2.09, 95% CI = 1.28–3.42). Quantitative trait analysis showed that rs2455391 was associated with positive symptoms, general symptoms and global symptoms but not with negative symptoms. The present results suggest that the DAT1 gene may be mainly involved in the development of the positive symptoms in the Chinese population.     

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.     

Searching for an immunogenetic factor that will illuminate susceptibility to non-tuberculous mycobacterial disease

The incidence of pulmonary non-tuberculous mycobacteria (NTM) disease in otherwise healthy adults is increasing as the population ages. The organisms are ubiquitous so susceptibility probably reflects a deficiency in a protective immune response. Here we investigate if singlenucleotide polymorphisms (SNP) affecting cytokines, chemokines and their receptors associate with pulmonary NTM disease. Samples from NTM patients (n = 79) and healthy controls (n = 188) were genotyped using TaqMan probes. Of the 16 SNPs assessed, IL28B-rs8099917^*TG (rs8099917; P = 0.01, OR = 2.2), TNFA-1031^*CC (rs1799964; p = 0.02, OR = 0.48) and IL10-1082^*AA (rs1800896; P = 0.001, OR = 0.33) were significantly associated with NTM disease. IL28B-rs8099917 and IL10-1082 have been associated with perturbations of the Th1/Th2 balance, whilst TNFA-1031^*CC associates with sensory neuropathy in HIV patients. IL10-1082 warrants further investigation because we observed high production of IL-10 in blood mononuclear cells from NTM patients.     

The Dopamine Receptor D2 (DRD2) SNP rs1076560 is Associated with Opioid Addiction

The risk for drug addiction is partially heritable. Genes of the dopamine system are likely candidates to harbour risk variants, as dopamine neurotransmission is involved in mediating the rewarding effects of drugs of abuse. One functional single nucleotide polymorphism in dopamine receptor D2 (DRD2), rs1076560, is involved in regulating splicing of the gene and alters the ratio of DRD2 isoforms located pre‐ and postsynaptically. rs1076560 has been previously associated with cocaine abuse and we set out to confirm this association in a sample of European American (EA) (n = 336) and African American (AA) (n = 1034) cocaine addicts and EA (n = 656) and AA (n = 668) controls. We also analysed the role of rs1076560 in opioid dependence by genotyping EA (n = 1041) and AA (n = 284) opioid addicts. rs1076560 was found to be nominally associated with opioid dependence in EAs (p = 0.02, OR = 1.27) and AAs (p = 0.03, OR = 1.43). When both opioid‐addicted ancestral samples were combined, rs1076560 was significantly associated with increased risk for drug dependence (p = 0.0038, OR = 1.29). This association remained significant after correction for multiple testing. No association was found with cocaine dependence. These data demonstrate the importance of dopamine gene variants in the risk for opioid dependence and highlight a functional polymorphism that warrants further study.     

HLA rs3129882 variant in Chinese Han patients with late-onset sporadic Parkinson disease

Recently, the rs3129882 variant in intron 1 of HLA-DRA was found to be associated with late-onset sporadic Parkinson disease (PD) in Americans of European ancestry. To evaluate whether the same variant is related to PD in Chinese population, we investigated late-onset sporadic PD patients of Chinese Han ethanicity in Mainland China. We found significant difference in genotypic and allele distribution between patients and control subjects (χ² = 6.446, p = 0.040 for genotypic distribution; χ² = 5.762, p = 0.016 for allele distribution), suggesting this variant is associated with late-onset sporadic PD in Chinese Han population.     

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.     

IL21 and IL21R polymorphisms and their interactive effects on serum IL-21 and IgE levels in patients with chronic hepatitis B virus infection

Interleukin (IL)-21 may affect both T-cell and B-cell responses and was suggested to be involved in response to HBV infection. This study explored IL21rs907715 and rs2221903 and IL21R T-83C and rs3093301 polymorphisms and serum IL-21 and IgE levels in 395 patients with chronic HBV infection, 75 HBV infection resolvers and 174 healthy controls. IL21R T-83C was not polymorphic in the study populations. IL21 rs2221903 AG was less frequent in HBV patients than in resolvers (p < 0.001, OR = 0.364, 95% CI = 0.211–0.629) or in controls (p = 0.017, OR = 0.589, 95% CI = 0.381–0.911). IL21R rs3093301 TT was more frequent in HBV patients than in controls [p value after Bonferroni correction (p_c) = 0.022, OR = 1.908, 95% CI = 1.158–3.142] and more frequent in resolvers than in controls (p_c = 0.010, OR = 2.965, 95% CI 1.375–6.392). The carriage of IL21 rs2221903 AG/IL21R rs3093301 CT + IL21 rs2221903 AG/IL21R rs3093301 TT was less frequent in patients than in resolvers (p_c = 0.007, OR = 0.236, 95% CI = 0.096–0.579) and more frequent in resolvers than in controls (p_c = 0.014, OR = 4.354, 95% CI = 1.660–11.420). IL21 rs2221903 was, by interaction with IL21R rs3093301, associated with serum IL-21 and IgE levels in HBV patients. It is suggested that IL21 rs2221903 and IL21R rs3093301 polymorphisms may, independently or interactively, affect the susceptibility to and/or persistence of HBV infection potentially through altering IL-21 and IgE production.     

Polymorphisms in thymic stromal lymphopoietin gene demonstrate a gender and nasal polyposis-dependent association with chronic rhinosinusitis

Background

Recent studies have suggested that thymic stromal lymphopoietin (TSLP), a key cytokine involved in the dendritic cell-mediated activation of Th2-mediated inflammatory responses, is significantly increased in nasal polyps from atopic individuals. Our objective was therefore to explore firstly any associations between single nucleotide polymorphisms (SNPs) in and around the TSLP gene and development of chronic rhinosinusitis (CRS; with (CRSwNP) or without (CRSsNP) nasal polyps and, and secondly the influence of nasal polyposis and gender.

Methods

A population-based case-control association analysis was performed in a Han Chinese cohort. DNA extracted from peripheral blood leukocytes from 638 subjects with CRS (306 CRSwNP and 332 CRSsNP) and 325 healthy controls was assessed for 11 SNPs in and around TSLP gene, selected from the Chinese HapMap genotyping dataset. Genetic association tests were performed using the Haploview and STATA software package.

Results

Single-locus analysis of CRS risk, showed no significant differences in allele or genotype frequencies between CRS subjects and controls. Stratified analyses of association between the selected SNPs and CRS adjusted for gender demonstrated that rs13156068 (CC genotype: P = 0.010, OR = 0.289) and rs764917 (CC genotype: P = 0.040, OR = 0.509) were significantly protective against CRS, whereas rs6886755 (GT genotype: P = 0.040, OR = 0.509) presented a risk among females. In contrast, rs764917 (CA genotype: P = 0.033, OR = 1.553) presented risk for CRS in males. Furthermore, SNPs rs252706 (AA genotype: P = 0.012, OR = 0.552) and rs764917 (CA genotype: P = 0.001, OR = 0.182) displayed protective roles among CRSwNP, but not CRSsNP, subjects.

Conclusions

This study suggests that SNPs in TSLP gene may exert a gender and/or nasal polyposis-dependent risk for development of CRS in Chinese subjects.     

Association of TLR4 and TLR5 gene polymorphisms with Graves’ disease in Chinese Cantonese population

Graves’ disease (GD) is postulated to be caused by the combined effects of susceptibility genes and environmental triggers. Toll like receptors (TLRs) play a role in the activation of innate and adaptive immune responses in mammalians. The aim of this study was to evaluate the potential association of TLR4 and TLR5 gene polymorphisms with GD in Chinese Cantonese population. Four single nucleotide polymorphisms (SNPs), rs11536889 and rs7873784 in TLR4, rs2072493 and rs5744174 in TLR5, were evaluated in 332 GD patients and 351 unrelated controls from Chinese Cantonese population. The minor allele C of TLR5 rs5744174 decreased the risk to GD in females (OR_{C vs. T} = 0.63; p = 0.003; p_trend = 0.003). Under a dominant model, rs5744174 conferred a protective effect in all cases (OR_{CC/CT vs. TT} = 0.65; p = 0.009) or female subset (OR_{CC/CT vs. TT} = 0.57; p = 0.002). Under a co-dominant model, rs5744174 also conferred a protective effect in all cases (OR_{TC vs. TT} = 0.64; p = 0.008) and females (OR_{TC vs. TT} = 0.57; p = 0.002). The haplotype A-C of TLR5 (rs2072493–rs5744174) decreased the risk of GD in females (OR = 0.62; p = 0.002). The other three SNPs were not found associated with GD. This study provided evidence that polymorphisms in TLR5 might be associated with decreased susceptibility of GD in females.     

IL10 polymorphisms associated with Behçet’s disease in Chinese Han

Objective

IL-10 is a potent anti-inflammatory cytokine that plays important roles in the pathogenesis of Behçet’s disease (BD). Two genome-wide association studies have identified IL10 as a potential risk factor for BD. Here, we investigated the association between IL10 polymorphisms and BD in Chinese Han.

Methods

407 BD patients and 679 healthy controls were enrolled, and genotyped by Sequenom MassArray system (Sequenom iPLEX assay, San Diego, CA).

Results

The frequency of risk allele of rs1800871 was notably higher in BD patients than in controls (71.9% vs. 66.2%, OR: 1.30, 95%CI: 1.08–1.58, p_c = 0.024). Similarly, rs1518111, which showed strong linkage disequilibrium (r² = 1) with allele rs1800871, was also associated with BD (p_c = 0.026). Rs3021094 was in association with BD in a dominant model (p_c = 0.035), and the haplotype (GACC) formed by rs1518111, rs3021094, rs3790622, and rs1800871 was associated with BD (p_c = 0.023). Results obtained from meta-analysis combined with our data showed that rs1800871 and rs1518111 were associated with BD.

Conclusion

IL10 may be the susceptibility gene for BD in Chinese Han population.     

Analysis of IL-17 gene polymorphisms in Chinese patients with dilated cardiomyopathy

Cardiomyopathy is one of the major causes of sudden death and/or progressive heart failure. Dilated cardiomyopathy (DCM), comprising 60% of the cases of identified cardiomyopathy, is the most common form of heart muscle disease. Interleukin 17 (IL-17) is a proinflammatory cytokine that has been implicated in the pathogenesis of various diseases. To evaluate the influence of IL-17A and IL-17F gene polymorphisms on the risk of DCM, a case-control study was conducted in a Chinese Han population. The TaqMan® SNP Genotyping Assay was used to genotype the SNP rs2275913 of IL-17A and SNP rs763780 of IL-17F in 288 DCM patients and 421 ethnicity-matched controls. No significant difference in genotypic and allelic frequencies between DCM patients and control subjects was observed. However, Results of stratified analysis revealed that rs763780 was associated with male DCM patients in a dominant genetic model (p = 0.031, OR = 1.83, 95% CI = 1.04–3.22). Our results suggest that the tested two IL-17 SNPs, rs2275913 and rs763780, are not found to be associated with DCM in the Chinese population studied.     

Genetic variations in toll-like receptor pathway and lung function decline in Cystic Fibrosis patients

The toll-like receptor (TLR) family maintains pulmonary homeostasis by pathogen recognition, clearance and regulation of inflammation. Genes affecting inflammation response play a key role in modifying Cystic fibrosis (CF) lung disease severity. We assessed the impact of single nucleotide polymorphisms (SNPs) of TLR genes (TLR1 to TLR10, CD14, lipopolyssacharide-binding protein (LBP)) on lung function in CF patients. Each SNP was tested for time-dependent effect on FEV1, using six genetic models. In addition, we investigated associations between SNP genotypes and extreme subject specific slopes of FEV1 decline. Variant alleles of polymorphisms of TLR2 rs1898830, rs5743708, and rs3804100 demonstrated a consistent association with lung disease severity (p = 0.008, p = 0.006 and p = 0.029 respectively). Patients homozygous for variant C allele of TLR5 polymorphism rs5744174 are more frequently associated with extreme fast FEV1 decline (OR: 20 (95% Confidence Interval:1.85–216.18)). Patients homozygous AA for TLR1 polymorphism rs5743551 are more frequently associated with faster decline of FEV1 compared to heterozygous genotype (OR:7.33 (95% CI:1.63–33.11). Our findings indicate that variations in TLR1, TLR2 and TLR5 genes may influence CF lung function decline. Further functional analysis is required to provide new insights into the pathogenesis of TLRs in CF lung disease severity.     

Association analysis between the Val66Met polymorphism in the brain-derived neurotrophic factor (BDNF) gene and treatment response to venlafaxine XR in generalized anxiety disorder

While antidepressant drugs are used to treat generalized anxiety disorder (GAD), patients vary greatly in their treatment response. Evidence shows genetic factors may play a role in treatment response in GAD. We examined whether the BDNF gene, which has been shown to play a role in antidepressant treatment response in major depressive disorder (MDD), also has an effect in GAD. In our study, 155 patients diagnosed with GAD received venlafaxine XR treatment as part of an 18-month relapse prevention study. Genotypes were obtained for the BDNF functional variant rs6265 (Val66Met) for the entire sample (n = 155); however, only the European American (EA) population was considered (n = 111) for pharmacogenetic analysis. We did not find a significant association between rs6265 and antidepressant treatment response in our GAD population. Future studies in larger populations will need to be conducted to further elucidate the pharmacogenetic role of this variant in anxiety disorders.     

Autoantigenicity of carbonic anhydrase 1 in patients with abdominal aortic aneurysm,revealed by proteomic surveillance

Abdominal aortic aneurysm (AAA) is sometimes detected in patients with atherosclerosis. One of the histological characteristics of AAA walls is infiltration of inflammatory cells, in which autoimmunity may be involved. Thereby, we here surveyed autoantigens in AAA walls by proteomics. Specifically, we separated proteins extracted from AAA wall samples by 2-dimensional electrophoresis and detected candidate autoantigens by western blotting. One of the detected candidates was carbonic anhydrase 1 (CA1). ELISA confirmed that the autoantibodies to CA1 were detected more frequently in AAA patients (n = 13) than in healthy donors (n = 25) (p = 0.03). Interestingly, some serum samples from the AAA patients reacted to CA1 of the AAA walls stronger than to CA1 of peripheral blood mononuclear cells from healthy donors. Our data indicate that CA1 in the AAA walls would be modified to express neo-epitope(s) and that the autoimmunity to CA1 may be involved in the pathogenesis of AAA.     

Association study on the NAPG gene and bipolar disorder in the Chinese Han population

Background: Bipolar disorder is a mental health problem throughout the world. Chromosome 18p11 has been identified by several studies as a susceptiblilty region for bipolar disorder and NAPG, located on 18p11, has been suggested as being associated with bipolar disorder in European population. Methods: Our study employed five SNPs (rs2290279, rs495484, rs510110, rs617040 and rs473938) to investigate the role of NAPG in the Chinese Han population based on a sample of 465 controls vs. 499 bipolar patients. Results: Rs617040 was excluded from further analysis because of deviation from Hardy–Weinberg equilibrium. Rs473938 and rs2290279 showed significant association in both allele and genotype frequencies (rs473938: allele p = 0.0028 after 100,000 permutations, genotype p = 0.0018; rs2290279: allele p = 0.0042 after 100,000 permutations, genotype p = 0.0028). Several combinations of haplotype were found to be associated with bipolar disorder. Haplotype T–A–T of rs473938–rs2290279–rs495484 was defined by confidence intervals algorithm and had a p value of 0.0038 after 100,000 permutations. Conclusions: Our study supports NAPG as a candidate for susceptibility to bipolar disorder.     

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.     

Association of the FTO and ADRB2 genes with body composition and fat distribution in obese women

Objective

The aim of this study was to investigate whether the polymorphisms of the fat mass and obesity-associated gene (FTO, rs9939609:T > A) and the β2-adrenergic receptor gene (ADRB2, rs1042714:Gln > Glu) are associated with weight loss in dieting obese premenopausal women and the association of these SNPs with body weight, body composition and distribution of fat mass.

Methods

75 obese (BMI > 30) premenopausal women participated in the intervention including a 3-month weight reduction period and a subsequent 9-month weight maintenance period. Weight and height were measured and BMI calculated. Body composition and fat mass distribution were assessed by dual energy X-ray absorptiometry.

Results

At baseline, the AA homozygotes of the FTO gene were 10.1 kg heavier (p = 0.031), they had higher BMI (p = 0.038), and greater waist and greater hip circumference (p = 0.08 and p = 0.067, respectively) compared to the TT homozygotes. Gln/Gln carriers of the ADRB2 gene had smaller gynoid fat-% compared with both the Gln/Glu and Glu/Glu carriers (p = 0.050 and p = 0.009, respectively). The Gln homozygotes had also smaller total body fat-% and higher total body lean mass-% than that of the Glu homozygotes (p = 0.018 and p = 0.019, respectively).

Conclusion

FTO genotype was associated with body weight in general, whereas ADRB2 genotype was associated with fat distribution. However, all women in the study group lost weight similarly independently of their genotypes. Neither the FTO nor ADRB2 genotype had statistically significant effect on weight reduction or weight maintenance.     

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.     

Genetic variations in tau-tubulin kinase-1 are linked to Alzheimer's disease in a Spanish case-control cohort

Neurofibrillary tangles, one of the characteristic neuropathological lesions found in Alzheimer's disease (AD) brains, are composed of abnormally hyperphosphorylated tau protein. Tau-tubulin kinase-1 (TTBK1) is a brain-specific protein kinase involved in tau phosphorylation at AD-related sites. We examined genetic variations of TTBK1 by genotyping nine haplotype tagging SNPs (htSNPs) (rs2104142, rs2651206, rs10807287, rs7764257, rs3800294, rs1995300, rs2756173, rs6936397, and rs6458330) in a group of 645 Spanish late-onset AD patients and 738 healthy controls. Using a recessive genetic model, minor allele homozygotes for rs2651206 in intron 1 (OR = 0.50, p = 0.0003), rs10807287 in intron 5 (OR = 0.49, p = 0.0002), and rs7764257 in intron 9 (OR = 0.57, p = 0.023), which are in strong linkage disequilibrium, had a lower risk of developing AD than subjects homozygotes and heterozygotes for the major allele. TTBK1 is a promising new candidate tau phosphorylation-related gene for AD risk.     

Common genetic variations in TPH1/TPH2 genes are not associated with schizophrenia in Japanese population

Alteration of serotonin transmission in the brain of patients with schizophrenia has been reported in postmortem brain studies, cerebrospinal fluid studies, and pharmacological challenges. Although a genetic association of tryptophan hydroxylase isoform 1 (TPH1), the rate-limiting enzyme in serotonin synthesis, with schizophrenia has been suggested by recent systematic meta-analyses, the newly identified neuronal isoform TPH2 is more relevant to the central nervous system and the association of TPH2 gene with schizophrenia has been much less explored. We, therefore, explored the association of TPH2 gene with schizophrenia using a case–control study of 720 Japanese populations and also tried to replicate the association of the TPH1 rs1800532 (A218C) single nucleotide polymorphism (SNP) with schizophrenia. We selected 15 tagging SNPs in the TPH2 gene. We found no significant differences in genotypic distributions (uncorrected P = 0.18–0.98) or allelic frequencies (uncorrected P = 0.18–0.98) of the 15 SNPs between the schizophrenia and control groups. Haplotypes constructed with these SNPs were also not associated with schizophrenia (uncorrected P = 0.12–0.97). The genotypic and allelic distribution of the TPH1 rs1800532 SNP was also not different between the case and control groups in our samples. In addition, a subsequent meta-analysis including our results did not showed a significant association with schizophrenia in Asian populations. Our findings suggest that neither common genetic variations of TPH1 nor TPH2 are likely to contribute to the genetic susceptibility to schizophrenia in Japanese population.