Analysis of serotonin receptor 2A gene (HTR2A): Association study with autism spectrum disorder in the Indian population and investigation of the gene expression in peripheral blood leukocytes

Several studies suggest involvement of serotoninergic system in the pathophysiology of Autism Spectrum Disorder (ASD). The 5-HT receptor binding studies using ³H-lysergic acid diethylamide (³H-LSD) and linkage analysis provided evidences to consider HTR2A as a potential candidate gene for ASD. The three SNPs, −1438A/G (rs6311), 102T/C (rs6313) and 1354C/T (rs6314) of HTR2A have been well studied in the etiology of various neuropsychiatric disorders. But studies on association of this gene with ASD are limited to two reports from American and Korean populations. Additionally there are reports, which demonstrated paternal imprinting of HTR2A with expression from only one allele. So far no reports are available on HTR2A and its association with any neuropsychiatric disorders from Indian population. Therefore, the present study investigates association of the above mentioned three markers of HTR2A with ASD in Indian population using population and family-based approaches. The study also deals with allelic expression pattern of HTR2A in Peripheral Blood Leukocytes (PBLs) to understand the parental imprinting status. The genotyping analyses were carried out for probands, parents and controls. The subsequent association analyses did not show association of these markers with ASD. So, HTR2A is unlikely to be a genetic marker for ASD in Indian population. The expression analyses showed absence of monoallelic expression, suggesting lack of parental imprinting of HTR2A gene. However, we noticed methylation of the CpG sites at −1438A/G and 102T/C loci of HTR2A gene. Further bioinformatics analysis revealed absence of CpG islands in the promoter of the gene supporting biallelic expression pattern of HTR2A in PBLs.     

Analysis of serotonin receptor 2A gene (HTR2A): Association study with autism spectrum disorder in the Indian population and investigation of the gene expression in peripheral blood leukocytes

Several studies suggest involvement of serotoninergic system in the pathophysiology of Autism Spectrum Disorder (ASD). The 5-HT receptor binding studies using ³H-lysergic acid diethylamide (³H-LSD) and linkage analysis provided evidences to consider HTR2A as a potential candidate gene for ASD. The three SNPs, −1438A/G (rs6311), 102T/C (rs6313) and 1354C/T (rs6314) of HTR2A have been well studied in the etiology of various neuropsychiatric disorders. But studies on association of this gene with ASD are limited to two reports from American and Korean populations. Additionally there are reports, which demonstrated paternal imprinting of HTR2A with expression from only one allele. So far no reports are available on HTR2A and its association with any neuropsychiatric disorders from Indian population. Therefore, the present study investigates association of the above mentioned three markers of HTR2A with ASD in Indian population using population and family-based approaches. The study also deals with allelic expression pattern of HTR2A in Peripheral Blood Leukocytes (PBLs) to understand the parental imprinting status. The genotyping analyses were carried out for probands, parents and controls. The subsequent association analyses did not show association of these markers with ASD. So, HTR2A is unlikely to be a genetic marker for ASD in Indian population. The expression analyses showed absence of monoallelic expression, suggesting lack of parental imprinting of HTR2A gene. However, we noticed methylation of the CpG sites at −1438A/G and 102T/C loci of HTR2A gene. Further bioinformatics analysis revealed absence of CpG islands in the promoter of the gene supporting biallelic expression pattern of HTR2A in PBLs.     

Association and interaction analyses of 5-HT3 receptor and serotonin transporter genes with alcohol,cocaine, and nicotine dependence using the SAGE data

Previous studies have implicated genes encoding the 5-HT3_AB receptors (HTR3A and HTR3B) and the serotonin transporter (SLC6A4), both independently and interactively, in alcohol (AD), cocaine (CD), and nicotine dependence (ND). However, whether these genetic effects also exist in subjects with comorbidities remains largely unknown. We used 1,136 African-American (AA) and 2,428 European-American (EA) subjects from the Study of Addiction: Genetics and Environment (SAGE) to determine associations between 88 genotyped or imputed variants within HTR3A, HTR3B, and SLC6A4 and three types of addictions, which were measured by DSM-IV diagnoses of AD, CD, and ND and the Fagerström Test for Nicotine Dependence (FTND), an independent measure of ND commonly used in tobacco research. Individual SNP-based association analysis revealed a significant association of rs2066713 in SLC6A4 with FTND in AA (β = ?1.39; P = 1.6E ? 04). Haplotype-based association analysis found one major haplotype formed by SNPs rs3891484 and rs3758987 in HTR3B that was significantly associated with AD in the AA sample, and another major haplotype T–T-G, formed by SNPs rs7118530, rs12221649, and rs2085421 in HTR3A, which showed significant association with FTND in the EA sample. Considering the biologic roles of the three genes and their functional relations, we used the GPU-based Generalized Multifactor Dimensionality Reduction (GMDR-GPU) program to test SNP-by-SNP interactions within the three genes and discovered two- to five-variant models that have significant impacts on AD, CD, ND, or FTND. Interestingly, most of the SNPs included in the genetic interaction model(s) for each addictive phenotype are either overlapped or in high linkage disequilibrium for both AA and EA samples, suggesting these detected variants in HTR3A, HTR3B, and SLC6A4 are interactively contributing to etiology of the three addictive phenotypes examined in this study.     

Association, interaction, and replication analysis of genes encoding serotonin transporter and 5-HT3 receptor subunits A and B in alcohol dependence

On the basis of the converging evidence showing regulation of drinking behavior by 5-HT_3AB receptors and the serotonin transporter, we hypothesized that the interactive effects of genetic variations in the genes HTR3A, HTR3B, and SLC6A4 confer greater susceptibility to alcohol dependence (AD) than do their effects individually. We examined the associations of AD with 22 SNPs across HTR3A, HTR3B, and two functional variants in SLC6A4 in 500 AD and 280 healthy control individuals of European descent. We found that the alleles of the low-frequency SNPs rs33940208:T in HTR3A and rs2276305:A in HTR3B were inversely and nominally significantly associated with AD with odds ratio (OR) and 95 % confidence interval of 0.212 and 0.073, 0.616 (P = 0.004) and 0.261 and 0.088, 0.777 (P = 0.016), respectively. Further, our gene-by-gene interaction analysis revealed that two four-variant models that differed by only one SNP carried a risk for AD (empirical P < 1 × 10^?6 for prediction accuracy of the two models based on 10⁶ permutations). Subsequent analysis of these two interaction models revealed an OR of 2.71 and 2.80, respectively, for AD (P < 0.001) in carriers of genotype combinations 5′-HTTLPR:LL/LS(SLC6A4)–rs1042173:TT/TG(SLC6A4)–rs1176744:AC(HTR3B)–rs3782025:AG(HTR3B) and 5′-HTTLPR:LL/LS(SLC6A4)–rs10160548:GT/TT(HTR3A)–rs1176744:AC(HTR3B)–rs3782025:AG(HTR3B). Combining all five genotypes resulted in an OR of 3.095 (P = 2.0 × 10^?4) for AD. Inspired by these findings, we conducted the analysis in an independent sample, OZ-ALC-GWAS (N = 6699), obtained from the NIH dbGAP database, which confirmed the findings, not only for all three risk genotype combinations (Z = 4.384, P = 1.0 × 10^?5; Z = 3.155, P = 1.6 × 10^?3; and Z = 3.389, P = 7.0 × 10^?4, respectively), but also protective effects for rs33940208:T (χ ² = 3.316, P = 0.0686) and rs2276305:A (χ ² = 7.224, P = 0.007). These findings reveal significant interactive effects among variants in SLC6A4–HTR3A–HTR3B affecting AD. Further studies are needed to confirm these findings and characterize the molecular mechanisms underlying these effects.     

NOS2A, TLR4, and IFNGR1 interactions influence pulmonary tuberculosis susceptibility in African-Americans

Tuberculosis (TB) has substantial mortality worldwide with 5–10% of those exposed progressing to active TB disease. Studies in mice and humans indicate that the inducible nitric oxide synthase (iNOS) molecule plays an important role in immune response to TB. A mixed case–control association study of individuals with TB, relatives, or close contact controls was performed in 726 individuals (279 case and 166 control African-Americans; 198 case and 123 control Caucasians). Thirty-nine single nucleotide polymorphisms (SNPs) were selected from the NOS2A gene for single SNP, haplotype, and multilocus interaction analyses with other typed candidate genes using generalized estimating equations. In African-Americans, ten NOS2A SNPs were associated with TB. The strongest associations were observed at rs2274894 (odds ratio (OR) = 1.84, 95% confidence interval (CI) [1.23–2.77], p = 0.003) and rs7215373 (OR = 1.67, 95% CI [1.17–2.37], p = 0.004), both of which passed a false discovery rate correction for multiple comparisons (q* = 0.20). The strongest gene–gene interactions were observed between NOS2A rs2248814 and IFNGR1 rs1327474 (p = 0.0004) and NOS2A rs944722 and IFNGR1 rs1327474 (p = 0.0006). Three other SNPs in NOS2A interacted with TLR4 rs5030729 and five other NOS2A SNPs interacted with IFNGR1 rs1327474. No significant associations were observed in Caucasians. These results suggest that NOS2A variants may contribute to TB susceptibility, particularly in individuals of African descent, and may act synergistically with SNPs in TLR4 and IFNGR1.     

Polymorphic variants of glutamate receptor (<Emphasis Type="Italic">GRIK5</Emphasis>, <Emphasis Type="Italic">GRIN2B</Emphasis>) and serotonin receptor (<Emphasis Type="Italic">HTR2A</Emphasis>) genes are associated with chronic

Chronic obstructive pulmonary disease (COPD) is a complex chronic inflammatory disease of the respiratory system that affects primarily distal respiratory pathways and lung parenchyma. Smoking tobacco is a major risk factor for COPD. The relationship of HTR4 (rs3995090), HTR2A (rs6313), GRIK5 (rs8099939), GRIN2B (rs2268132), and CHRNB4 (rs1948) gene polymorphisms and COPD, as well as the contribution of these polymorphisms to the variations in quantitative characteristics that describe respiratory function, smoking behavior, and nicotine dependence was assessed in an ethnically homogeneous Tatar population. The polymorphisms of HTR2A (rs6313) (P = 0.026, OR = 1.42 for the CC genotype) and GRIN2B (rs2268132) (P = 0.0001, OR = 2.39 for the TT genotype) were significantly associated with increased risk of COPD. The AA genotype of GRIK5 (rs8099939) had a protective effect (P = 0.02, OR = 0.61). Importantly, the HTR2A (rs6313), GRIN2B (rs2268132), and GRIK5 (rs8099939) polymorphisms were only associated with COPD in smokers. Smoking index (pack-years) was significantly higher in carriers of the GRIK5 genotype AC (rs8099939) (P = 0.0027). The TT genotype of GRIN2B (rs2268132) was associated with COPD in subjects with high nicotine dependence according to the Fagerström test (P = 0.002, OR = 2.98). The TT genotype of HTR2A (rs6313) was associated with a reduced risk of the disease in the group with moderate nicotine dependence (P = 0.02, OR = 0.22). The CC genotype of HTR2A (rs6313) and the TT genotype of GRIN2B (rs2268132) were associated with higher levels of nicotine dependence according to the Fagerström test (P = 0.0011 and P = 0.037). Our results may provide insight into potential molecular mechanisms that involve the glutamate (GRIK5, GRIN2B) and serotonin (HTR2A) receptor genes in the pathogenesis of COPD.     

Association Analysis of IGF2BP2, KCNJ11, and CDKAL1 Polymorphisms with Type 2 Diabetes Mellitus in a Moroccan Population: A Case–Control Study and Meta-analysis

Associations with type 2 diabetes mellitus have been identified for variants CDKAL1 rs7756992, KCNJ11 rs5219, and IGF2BP2 rs4402960 in different populations. In a case–control study of 250 unrelated Moroccan diabetic patients and 250 healthy controls, we used TaqMan allelic discrimination assays to genotype the three SNPs and meta-analysis to investigate the association between the polymorphisms and diabetes in Arab populations. The results showed a significant diabetes association only with the variant rs4402960 of the IGF2BP2 gene under additive 2 (GG vs. TT; p = 0.009) and recessive (TT vs. GG+GT; p = 0.003) models. Meta-analysis indicated significant association between the IGF2BP2 rs4402960 and CDKAL1 rs7756992 polymorphisms and increased risk of diabetes in Arab populations. According to our results, the case–control study and meta-analysis revealed a significant association between the IGF2BP2 rs4402960 variant and type 2 diabetes in Moroccan and Arab populations.     

Association of common variants in KIF21B and ankylosing spondylitis in a Chinese Han population: a replication study

KIF21B polymorphisms were found associated with susceptibility to multiple sclerosis and ankylosing spondylitis (AS) in populations of white European ancestry. We aimed to replicate the association of polymorphisms around KIF21B and AS in a Chinese Han population. This case–control study included 665 patients with AS and 1,042 healthy controls genotyped for seven single nucleotide polymorphisms (SNPs) of KIF21B—rs12118246, rs4915464, rs502658, rs10494829, rs12089839, rs6687260, and rs957957—by TaqMan genotyping assay; statistical analyses involved the use of PLINK. We also estimated the linkage disequilibrium and haplotypes of these SNPs. Two SNPs—rs502658 (allelic p?=?0.0002, odds ratio [OR] 0.60, 95 % confidence interval [95 % CI] 0.47–0.76) and rs10494829 (allelic p?=?0.003, OR 1.30, 95 % CI 1.12–1.52)—were significantly associated with AS in the Chinese Han population. In addition, a linear regression test showed that they have independent contribution to disease susceptibility. For both SNPs, haplotype AT was strongly associated with AS and increased the risk of the disease (p?=?0.045, OR 1.183, 95 % CI 1.004–1.395), and the genotype GC reduced the risk (p?=?0.011, OR 0.715, 95 % CI 0.55–0.928). This work identified a significant association of two SNPs in KIF21B and AS in the Chinese Han population. KIF21B may play an important role in the pathogenesis of AS in the Chinese population and might be a new therapeutic target for AS.     

Association between <Emphasis Type="Italic">PNPLA3</Emphasis> rs738409 polymorphism and hepatocellular carcinoma risk: an updated meta-analysis

Hepatocellular carcinoma (HCC) is a common malignant tumor and the leading cause of cancer-related death worldwide. The protein encoded by patatin-like phospholipase domain-containing protein 3 (PNPLA3) plays important roles in liver fatty metabolism. Recent studies have indicated associations of PNPLA3 rs738409 with various liver diseases, including HCC. This meta-analysis was performed to investigate and update the association between rs738409 polymorphism and the risk of HCC, and to test the association between rs738409 and HCC specifically in patients within chronic hepatitis B and/or C infection, alcoholic liver disease, or other diseases. Studies were searched from the literature database up to March 31, 2016. The meta-analysis was conducted based on statement of preferred reporting items for systematic reviews and meta-analyses. Pooled odds ratios (OR) and 95 % confidence intervals (CI) were estimated the strength of associations between rs738409 polymorphism and HCC risk. Fifteen published studies, consisting of 2264 HCC patients (case) and 5802 without HCC individuals (control), were included in the present study. Meta-analysis revealed that rs738409 polymorphism contributed to HCC risk under the allelic effect model (C vs. G: OR 1.73; 95 % CI   1.53–1.96), the dominant effect model (CC vs. CG+GG: OR 1.61; 95 % CI 1.44–1.81), and the recessive effect model (CC+CG vs. GG: OR 2.66; 95 % CI 2.28–3.11). Furthermore, the effect of rs738409 G allele on liver oncogenesis was higher in alcoholic liver disease (OR 2.55), compared to chronic hepatitis C/B (OR 1.32) and other diseases (OR 2.27). The results suggested that rs738409 polymorphism was significantly associated with HCC risk and it could be used as one risk factor for HCC.     

Association between variants of EXT2 and type 2 diabetes: a replication and meta-analysis

Recent publications have found an association between variants of exostosin 2 (EXT2) gene and the risk of type 2 diabetes in some population but not in others. In an attempt to address these inconsistencies, we investigated EXT2 variants in two independent cohorts, and conducted a literature-based meta-analysis. Through regression model, we assessed the relationship between the EXT2 single nucleotide polymorphisms (SNPs) (rs3740878, rs11037909 and rs1113132) and the risk of type 2 diabetes in Han Chinese population, including a total of 2,533 cases and 2,643 controls. We combined our data with that from previously published studies and performed a meta-analysis to evaluate the effect size of the gene. Consistent with some studies, we found marginal association for the rs3740878 (OR = 1.07, 95 % CI = 0.99, 1.16, p = 0.09), rs11037909 (OR = 1.07, 95 % CI = 0.99, 1.16, p = 0.08), and rs1113132 (OR = 1.08, 95 % CI = 1.00, 1.17, p = 0.06) in our 2 cohorts. Meta-analysis, comprising 9,224 type 2 diabetes and 10,484 controls, revealed that three SNPs (rs3740878, rs11037909 and rs1113132) in EXT2 were significantly associated with type 2 diabetes (ORs range from 1.06 to 1.07, p = 0.038, p = 0.008 and p = 0.005, respectively). Variation in the EXT2 locus appears to be associated with a small increase in the risk of type 2 diabetes. However, well-designed prospective studies with larger sample size and more ethnic groups are needed to further validate the results.     

Association analyses between the genetic polymorphisms of HNF4A and FOXO1 genes and Chinese Han patients with type 2 diabetes

The hepatocyte nuclear factor 4-alpha (HNF4A) and human forkhead box O1 (FOXO1) genes have been discovered to be associated with type 2 diabetes (T2D) in different populations. This study aimed to evaluate the association between HNF4A and FOXO1 genetic polymorphisms and type 2 diabetes in the Chinese Han population. Five hundred and seventy-seven patients with type 2 diabetes and 462 normal controls were enrolled in this study. Six single-nucleotide polymorphisms (SNPs) in HNF4A and seven in FOXO1 were selected and genotyped with polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) or TaqMan^® technology. Single-locus analyses indicated that the C allele of rs11574736 from HNF4A had a lower frequency in the case group compared with the control group (P = 0.005, OR = 0.74, 95% CI = 0.59–0.92). The genotype distributions of rs11574736 also differed between the two groups (P = 0.02). However, none of the FOXO1 SNPs showed any association with type 2 diabetes in the Chinese Han population. Further analysis suggested the two genes interact with each other (rs3908773/rs717247/rs6031587/rs11574736: P < 0.0001, testing accuracy = 0.55, CV consistency = 6/10). In conclusion, this study shows an association between the HNF4A gene and type 2 diabetes in the Chinese Han population. Moreover, the authors confirmed the results of previous studies for the interaction between HNF4A and FOXO1 in the pathogenesis of type 2 diabetes.     

Association of TERT-CLPTM1L and 8q24 Common Genetic Variants with Gallbladder Cancer Susceptibility and Prognosis in North Indian Population

Gallbladder carcinoma (GBC) is one of the common malignancy of the biliary tract. Several genome wide and candidate gene studies have reported associations between multiple cancer types and single-nucleotide polymorphisms on 5p15.33 and 8q24.21 loci. However, predisposition potential of these genetic variants has not been assessed in GBC. We performed the present study to assess the potential of five polymorphisms on 5p15.33 and one on 8q24.21 locus in GBC risk and treatment response in patients undergoing chemoradiotherapy. We extracted genomic DNA from peripheral blood and genotyped selected SNPs using TaqMan allelic discrimination assays in 523 GBC cases and 274 controls from the north-Indian population. Statistical tests were performed to assess the association of selected common genetic variants with gallbladder cancer susceptibility and prognosis. Binary logistic regression analysis showed significant association of TERT rs2736100C > A [OR(CI) = 0.690(0.515–0.924), p value = 0.013], CLPTM1L rs401681C > T [OR(CI) = 0.586(0.405–0.847), p value = 0.004], and CASC8 rs6983267G > T [OR(CI) = 1.629(1.215–2.186), p value = 0.001] with GBC risk. Further, using multivariate logistic regression, we observed that haplotype CLPTM1L C_rs401681C_rs31489 TERT T_rs2853676A_rs2736100 MIR4457 G_rs4635969 [OR(CI) = 7.52 (1.79–31.52), p value = 0.0064] is significantly associated with poor treatment response. In survival analysis, Kaplan–Meier survival curves showed significantly poor survival and COX regression suggested significantly higher hazard ratio in TT genotype carriers of CASC8 rs6983267 [OR(CI) = 4.28(1. 07–17.10), p value = 0.040] as compared to major allele and heterozygous (GG+GT) genotypes in metastatic GBC cases. The study revealed that 5p15.33 and 8q24.21 genetic variants significantly influence GBC risk and treatment response in north-Indian population.     

The association of apolipoprotein E gene polymorphisms with cerebral palsy in Chinese infants

Apolipoprotein E (APOE, protein; ApoE, gene) is a lipid transport protein abundantly present in brain cells. Previous studies have suggested that there is an association between genetic variants of ApoE and susceptibility to cerebral palsy (CP). The purpose of this study was to explore whether the ApoE gene is involved in the etiology of CP in the Chinese population. In this study, 350 CP patients and 242 healthy control children were recruited. Genomic DNA was prepared from venous blood and all five single nucleotide polymorphisms (SNPs) in ApoE (rs769446, rs405509, rs121918399, rs429358, and rs190853081) were detected by the MassARRAY platform-based genotyping approach. The SHEsis program was used to analyze the genotyping data, and we systemically analyzed the association of the ApoE SNPs with different subtypes of CP. No significant association was detected between the e4 identified by the C allele of rs429358 and CP, but there were significant differences in allelic frequencies between the CP patients and controls at rs769446 (P = 0.005, P = 0.025 after Bonferroni correction), as well as between the CP patients with preterm birth (<34 gestational weeks) and controls at rs769446 (P = 0.001, P = 0.005 after Bonferroni correction). A haplotype consisting of the five SNPs rs769446(C), rs405509(C), rs121918399(C), rs429358(T), and rs190853081(G) was associated with a decreased risk of CP (P = 0.002 after Bonferroni correction). However, we found no significant association between any of the other three SNPs and CP based on different subgroup analyses. This study provides the first evidence that ApoE gene polymorphisms are a potential risk factor for CP in the Chinese population.     

Identification of genetic associations of SP110/MYBBP1A/RELA with pulmonary tuberculosis in the Chinese Han population

Genetic factors play important roles in the development of tuberculosis (TB). SP110 is a promising candidate target for controlling TB infections. However, several studies associating SP110 single nucleotide polymorphisms (SNPs) with TB have yielded conflicting results. This may be partly resolved by studying other genes associated with SP110, such as MYBBP1A and RELA. Here, we genotyped 6 SP110 SNPs, 8 MYBBP1A SNPs and 5 RELA SNPs in 702 Chinese pulmonary TB patients and 425 healthy subjects using MassARRAY and SNaPshot methods. Using SNP-based analysis with Bonferroni correction, rs3809849 in MYBBP1A [Pcorrected (cor) = 0.0038] and rs9061 in SP110 (Pcor = 0.019) were found to be significantly associated with TB. Furthermore, meta-analysis of rs9061 in East Asian populations showed that the rs9061 T allele conferred significant risk for TB [P = 0.002, pooled odds ratio (OR), 1.24, 95 % confidence interval (CI) = 1.08–1.43]. The MYBBP1A GTCTTGGG haplotype and haplotypes CGACCG/TGATTG within SP110 were found to be markedly and significantly associated with TB (P = 2.00E?06, 5.00E?6 and 2.59E?4, respectively). Gene-based analysis also demonstrated that SP110 and MYBBP1A were each associated with TB (Pcor = 0.011 and 0.035, respectively). The logistic regression analysis results supported interactions between SP110 and MYBBP1A, indicating that subjects carrying a GC/CC genotype in MYBBP1A and CC genotype in SP110 possessed the high risk of developing TB (P = 1.74E?12). Our study suggests that a combination of SP110 and MYBBP1A gene polymorphisms may serve as a novel marker for identifying the risk of developing TB in the Chinese Han population.     

Association of ADIPOQ gene with obesity and adiponectin levels in Malaysian Malays

Studies have shown that single-nucleotide polymorphisms (SNPs) on the ADIPOQ gene have been linked with obesity and with adiponectin levels in various populations. Here, we aimed to investigate the association of ADIPOQ rs17366568 and rs3774261 SNPs with obesity and with adiponectin levels in Malaysian Malays. Obesity parameters and adiponectin levels were measured in 574 subjects. Genotyping was performed using real-time polymerase chain reaction and Sequenom MassARRAY. A significant genotypic association was observed between ADIPOQ rs17366568 and obesity. The frequencies of AG and AA genotypes were significantly higher in the obese group (11 %) than in the non-obese group (5 %) (P = 0.024). The odds of A alleles occurring among the obese group were twice those among the non-obese group (odds ratio 2.15; 95 % confidence interval 1.13–4.09). However, no significant association was found between allelic frequencies of ADIPOQ rs17366568 and obesity after Bonferroni correction (P > 0.025) or between ADIPOQ rs3774261 and obesity both at allelic and genotypic levels. ADIPOQ SNPs were not significantly associated with log-adiponectin levels. GA, GG, and AG haplotypes of the ADIPOQ gene were not associated with obesity. We confirmed the previously reported association of ADIPOQ rs17366568 with the risk of obesity. ADIPOQ SNPs are not important modulators of adiponectin levels in this population.     

The association of rs1149048 polymorphism in Matrilin-1(MATN1) gene with adolescent idiopathic scoliosis susceptibility: a meta-analysis

Several previous studies have evaluated the association between rs1149048 polymorphism in the matrilin-1 gene (MATN1) and the risk of adolescent idiopathic scoliosis (AIS). However the results of those studies were inconsistent. We conducted this meta-analysis to assess whether rs1149048 polymorphism was involved in the risk of AIS and evaluated the associations in different ethnicities. Electronic databases, such as: PubMed, EMBASE, WANFANG databases in any languages up to Dec 2012 were searched to assess the association between rs1149048 polymorphism and AIS. Meta-analysis was performed by STATA 12.0 software to estimate the pooled odds ratio (OR) and the 95 % confidence interval (CI). Finally four papers including five studies which involved 1436 AIS patients and 1,879 controls were identified for this meta-analysis. The results showed that G allele of the rs1149048 was significantly associated with increased AIS risk [OR = 1.13, 95 % CI (1.02–1.25), P = 0.023]. As for genotype (GG vs. GA + AA), homozygous GG genotype was also found to be a risk factor of developing AIS. The subgroup meta-analysis results showed G allele and GG genotype were significantly associated with AIS in Asian group but not in Caucasian group. Neither Egger’s test nor Begg’s test found evidence of publication bias in current study (P > 0.05). In summary, this meta-analysis found an overall significant association of rs1149048 polymorphism with risk of AIS, especially in Asian population. The relationship between rs1149048 polymorphism and AIS in other ethnic population is needed to be investigated.     

Polymorphisms of Genes in Neurotransmitter Systems Were Associated with Alcohol Use Disorders in a Tibetan Population

Studies of linkage and association in various ethnic populations have revealed many predisposing genes of multiple neurotransmitter systems for alcohol use disorders (AUD). However, evidence often is contradictory regarding the contribution of most candidate genes to the susceptibility of AUD. We, therefore, performed a case-control study to investigate the possible associations of genes selected from multiple neurotransmitter systems with AUD in a homogeneous Tibetan community population in China. AUD cases (N = 281) with an alcohol use disorder identification test (AUDIT) score ≥10, as well as healthy controls (N = 277) with an AUDIT score ≤5, were recruited. All participants were genotyped for 366 single nucleotide polymorphisms (SNPs) of 34 genes selected from those involved in neurotransmitter systems. Association analyses were performed using PLINK version 1.07 software. Allelic analyses before adjustment for multiple tests showed that 15 polymorphisms within seven genes were associated with AUD (p<0.05). After adjustment for the number of SNPs genotyped within each gene, only the association of a single marker (rs10044881) in HTR4 remained statistically significant. Haplotype analysis for two SNPs in HTR4 (rs17777298 and rs10044881) showed that the haplotype AG was significantly associated with the protective effect for AUD. In conclusion, the present study discovered that the HTR4 gene may play a marked role in the pathogenesis of AUD. In addition, this Tibetan population sample marginally replicated previous evidence regarding the associations of six genes in AUD.     

DNMT1, DNMT3A and DNMT3B gene variants in relation to ovarian cancer risk in the Polish population

Studies have demonstrated that changes in DNA methylation of cancer related genes can be an elementary process accounting for ovarian tumorigenesis. Therefore, we evaluated the possible association of single nucleotide polymorphisms (SNPs) of DNA methyltransferases (DNMTs) genes, including DNMT1, DNMT3B, and DNMT3A, with ovarian cancer development in the Polish population. Using PCR–RFLP and HRM analyses, we studied the prevalence of the DNMT1 rs8101626, rs2228611 and rs759920, DNMT3A rs2289195, 7590760, rs13401241, rs749131 and rs1550117, and DNMT3B rs1569686, rs2424913 and rs2424932 SNPs in patients with ovarian cancer (n = 159) and controls (n = 180). The lowest p values of the trend test were observed for the DNMT1 rs2228611 and rs759920 SNPs in patients with ovarian cancer (p _trend = 0.0118 and p _trend = 0.0173, respectively). Moreover, we observed, in the recessive inheritance model, that the DNMT1 rs2228611 and rs759920 SNPs are associated with an increased risk of ovarian cancer development [OR 1.836 (1.143–2.949), p = 0.0114, p _corr = 0.0342, and OR 1.932 (1.185–3.152), p = 0.0078, p _cor=0.0234, respectively]. However, none of other nine studied SNPs displayed significant contribution to the development of ovarian cancer. Furthermore, haplotype and multifactor dimensionality reduction analysis of the studied DNMT1, DNMT3B, and DNMT3A polymorphisms did not reveal either SNP combinations or gene interactions to be associated with the risk of ovarian cancer development. Our results may suggest that DNMT1 variants may be risk factors of ovarian cancer.     

Common genetic variants (rs4779584 and rs10318) at 15q13.3 contributes to colorectal adenoma and colorectal cancer susceptibility: evidence based on 22 studies

Several genome-wide association studies on colorectal cancer (CRC) have reported similar findings of a new susceptibility locus, 15q13.3. After that, a number of studies have reported that the rs4779584 and rs10318 polymorphisms at chromosome 15q13.3 have been implicated in CRC and colorectal adenoma (CRA) risk; however, these studies have yielded inconsistent results. To investigate this inconsistency, we performed a meta-analysis of 22 studies involving a total of 48,468 CRC cases, 4,189 CRA cases, and 85,105 controls for the two polymorphisms to evaluate its effect on genetic susceptibility for CRC/CRA. Potential sources of heterogeneity and publication bias were also systematically explored. Overall, the summary odds ratio (OR) of rs4779584-T variant for CRC was 1.13 (95 % CI 1.09–1.16, P < 10^?5) and 1.15 (95 % CI 1.04–1.28, P = 0.006) for CRA. After stratified by ethnicity, significantly increased CRC risks were found for rs4779584 polymorphism among East Asians and Caucasians, while no significant associations were detected among African American and other ethnic populations. A meta-analysis of studies on the rs10318 polymorphism also showed significant overall association with CRC, yielding a per-allele OR of 1.13 (95 % CI 1.02–1.24, P = 0.02). In the subgroup analysis by ethnicity, significantly increased CRC risks were found in Caucasians; whereas no significant associations were found among East Asians and African Americans. This meta-analysis demonstrated that the rs4779584 and rs10318 polymorphism at 15q13.3 is a risk factor associated with increased CRC/CRA susceptibility, but these associations vary in different ethnic populations.     

A meta-analysis of two genome-wide association studies to identify novel loci for maximum number of alcoholic drinks

Maximum number of alcoholic drinks consumed in a 24-h period (maxdrinks) is a heritable (>50 %) trait and is strongly correlated with vulnerability to excessive alcohol consumption and subsequent alcohol dependence (AD). Several genome-wide association studies (GWAS) have studied alcohol dependence, but few have concentrated on excessive alcohol consumption. We performed two GWAS using maxdrinks as an excessive alcohol consumption phenotype: one in 118 extended families (N = 2,322) selected from the Collaborative Study on the Genetics of Alcoholism (COGA), and the other in a case–control sample (N = 2,593) derived from the Study of Addiction: Genes and Environment (SAGE). The strongest association in the COGA families was detected with rs9523562 (p = 2.1 × 10^?6) located in an intergenic region on chromosome 13q31.1; the strongest association in the SAGE dataset was with rs67666182 (p = 7.1 × 10^?7), located in an intergenic region on chromosome 8. We also performed a meta-analysis with these two GWAS and demonstrated evidence of association in both datasets for the LMO1 (p = 7.2 × 10^?7) and PLCL1 genes (p = 4.1 × 10^?6) with maxdrinks. A variant in AUTS2 and variants in INADL, C15orf32 and HIP1 that were associated with measures of alcohol consumption in a meta-analysis of GWAS studies and a GWAS of alcohol consumption factor score also showed nominal association in the current meta-analysis. The present study has identified several loci that warrant further examination in independent samples. Among the top SNPs in each of the dataset (p ≤ 10^?4) far more showed the same direction of effect in the other dataset than would be expected by chance (p = 2 × 10^?3, 3 × 10^?6), suggesting that there are true signals among these top SNPs, even though no SNP reached genome-wide levels of significance.