High-risk Haplotype Research Articles

Rho-Associated Kinase 2 Polymorphism of Vasospastic Angina in Korean Population

Rho-Associated Kinase 2 Polymorphism of Vasospastic Angina in Korean Population

A rare penetrant mutation in CFH confers high risk of age-related macular degeneration

Two common variants within CFH, the Y402H1–4 and the rs1410996 SNPs5,6, explain 17% of age-related macular degeneration (AMD) liability. However, proof for the involvement of CFH, as opposed to a neighboring transcript, and the potential mechanism of susceptibility alleles are lacking. Assuming that rare functional variants might provide mechanistic insights, we used genotype data and high throughput sequencing to discover a rare high-risk CFH haplotype containing an R1210C mutation. This allele has been implicated previously in atypical hemolytic uremic syndrome, and abrogates C-terminal ligand binding7,8. Genotyping R1210C in 2,423 AMD cases and 1,122 controls demonstrated high penetrance (present in 40 cases versus 1 control, p=7.0×10−6) and six year earlier onset of disease (p=2.3×10−6). This result suggests that loss of function alleles at CFH likely drive AMD risk. This finding represents one of the first instances where a common complex disease variant has led to discovery of a rare penetrant mutation.

Replication and further characterization of a Type 1 diabetes-associated locus at the telomeric end of the major histocompatibility complex

We recently reported an association between Type 1 diabetes and the telomeric major histocompatibility complex (MHC) single nucleotide polymorphism (SNP) rs1233478. As further families have been analyzed in the Type 1 Diabetes Genetics Consortium (T1DGC), we tested replication of the association and, with more data, analyzed haplotypic associations. An additional 2717 case and 1315 control chromosomes have been analyzed from the T1DGC, with human leukocyte antigen (HLA) typing and data for 2837 SNPs across the MHC region. We confirmed the association of rs1233478 (new data only: P=2.2E-5, OR=1.4). We also found two additional SNPs nearby that were significantly associated with Type 1 diabetes (new data only rs3131020: P=8.3E-9, OR=0.65; rs1592410: P=2.2E-8, OR=1.5). For studies of Type 1 diabetes in the MHC region, it is critical to account for linkage disequilibrium with the HLA genes. Logistic regression analysis of these new data indicated that the effects of rs3131020 and rs1592410 on Type 1 diabetes risk are independent of HLA alleles (rs3131020: P=2.3E-3, OR=0.73; rs1592410: P=2.1E-3, OR=1.4). Haplotypes of 12 SNPs (including the three highly significant SNPs) stratify diabetes risk (high risk, protective, and neutral), with high-risk haplotypes limited to approximately 20,000 bp in length. The 20,000-bp region is telomeric of the UBD gene and contains LOC729653, a hypothetical gene. We believe that polymorphisms of the telomeric MHC locus LOC729653 may confer risk for Type 1 diabetes.

Homozygosity for the rs9939609T allele of the FTO gene may have protective effect on becoming overweight in survivors of childhood acute lymphoblastic leukaemia

Approximately 20% of adolescents and children in Europe are overweight, and 30% of those who are overweight actually fulfill the criteria of obesity (Branca et al. 2007). The prevalence of obesity in survivors of acute lymphoblastic leukaemia (ALL) is 16 to 57% (Gregory and Reilly 2004). Among others, cranial radiotherapy (CRT) and genetic factors have been implicated as risk factors of overweight/obesity (Ross et al. 2004; Chow et al. 2007). The fat mass and obesity associated gene (FTO) has been recently found to contribute to the risk of obesity. Polymorphism of rs9939609 T>A was associated with an increased BMI in children aged ≥7 years. Individuals homozygous for A allele at rs9939609 constituted 16% of the population and population risk was 20.4% for obesity and 12.7% for overweight (Frayling et al. 2007). The high-risk FTO haplotype yielded a proportion of attributable risk of 22% for uncomplicated obesity in adults and children of European ancestry (Dina et al. 2007). Therefore, the influence of rs9939609 T>A polymorphism of FTO gene on overweight in leukaemia survivors was studied. A total of 191 patients were genotyped for the above genetic variant. Significant negative association between the rs9939609T allele and prevalence of overweight status was found in a subset of patients treated with CRT. Patients who receive CRT and are carriers of this variant may be protected from becoming overweight.

Candidate gene studies in gallbladder cancer: A systematic review and meta-analysis

Gallbladder cancer (GBC) is the most frequent biliary tract malignancy. Wide variations in GBC incidence and familial and epidemiological data suggest involvement of a genetic component in its etiopathogenesis. A systematic review of genetic association studies in GBC was performed by applying a meta-analysis approach and systematically reviewing PubMed database using appropriate terms. Odds ratios (ORs) and 95% confidence intervals (CIs) were appropriately derived for each gene-disease association using fixed and random effect models. Meta-regression with population size and genotyping method was also performed. Study quality was assessed using a 10-point scoring system designed from published guidelines. Following a review of 44 published manuscripts and one unpublished report, 80 candidate gene variants and 173 polymorphisms were analyzed among 1046 cases and 2310 controls. Majority of studies were of intermediate quality. Four polymorphisms with >3 separate studies were included in the meta-analysis [OGG1 (rs1052133), TP53 (rs1042522), CYP1A1 (rs1048943) and GSTM1 null polymorphism]. The meta-analysis demonstrated no significant associations of any of the above polymorphisms with GBC susceptibility except TP53 (rs1042522) polymorphism. To conclude, existing candidate gene studies in GBC susceptibility have so far been insufficient to confirm any association. Future research should focus on a more comprehensive approach utilizing potential gene-gene, gene-environment interactions and high-risk haplotypes.

<italic>ADIPOQ</italic> Gene Variants Associated with Susceptibility to Obesity and Low Serum Adiponectin Levels in Healthy Koreans

OBJECTIVESThis study aimed to measure the association between the adiponectin, C1Q and collagen domain-containing (ADIPOQ) gene variants and obesity in Koreans.METHODSThree single nucleotide polymorphisms located in the ADIPOQ gene were genotyped in a population-based cross-sectional study of 986 healthy Koreans. Three different case-control groups (i.e. G1, G2, and G3) were defined according to body mass index (BMI) and serum adiponectin levels. Allelic and genotypic associations of this gene with obesity were measured using multivariate logistic regression analyses in each group.RESULTSThe G allele of -11377C>G, a polymorphism located in the promoter region of the ADIPOQ gene (odds ratio (OR), 1.48; 95% confidence interval, 1.13-1.94) and most haplotypes including this allele significantly increased the risk for obesity. However, the OR decreased from 3.98 (G1 group) to 2.90 (G2 group) and 2.30 (G3 group) when a less strict definition of obesity was used. Most haplotypes, including this allele, significantly increased the risk of obesity. The statistical evidence from the GG genotype of -11377C>G (OR, 3.98) and the GT/GT diplotype composed of -11377G>C and +45T>G (OR, 5.20) confirmed the contribution of the G allele toward a predisposition for obesity.CONCLUSIONThese results suggest the contribution of the ADIPOQ gene toward susceptibility to obesity in healthy Koreans. The high-risk genotypes and haplotypes identified here may provide more information for identifying individuals who are at risk of obesity.

CD4 Intragenic SNPs Associate With HIV-2 Plasma Viral Load and CD4 Count in a Community-Based Study From Guinea-Bissau, West Africa

The human genetics of HIV-2 infection and disease progression is understudied. Therefore, we studied the effect of variation in 2 genes that encode products critical to HIV pathogenesis and disease progression: CD4 and CD209. This cross-sectional study consisted of 143 HIV-2, 30 HIV-1 + HIV-2 and 29 HIV-1-infected subjects and 194 uninfected controls recruited from rural Guinea-Bissau. We genotyped 14 CD4 and 4 CD209 single nucleotide polymorphisms (SNPs) that were tested for association with HIV infection, HIV-2 plasma viral load (high vs. low), and CD4 T-cell count (high vs. low). The most significant association was between a CD4 haplotype rs11575097-rs10849523 and high viral load [odds ratio (OR): = 2.37, 95% confidence interval (CI): 1.35 to 4.19, P = 0.001, corrected for multiple testing], suggesting increased genetic susceptibility to HIV-2 disease progression for individuals carrying the high-risk haplotype. Significant associations were also observed at a CD4 SNP (rs2255301) with HIV-2 infection (OR: = 2.36, 95% CI: 1.19 to 4.65, P = 0.01) and any HIV infection (OR: = 2.50, 95% CI: 1.34 to 4.69, P = 0.004). Our results support a role of CD4 polymorphisms in HIV-2 infection, in agreement with recent data showing that CD4 gene variants increase risk to HIV-1 in Kenyan female sex workers. These findings indicate at least some commonality in HIV-1 and HIV-2 susceptibility.

Genetic marker polymorphisms on chromosome 8q24 and prostate cancer in the Dutch population: DG8S737 may not be the causative variant

Prostate cancer is the most commonly diagnosed cancer in men in Europe and Northern America. Genome-wide association studies (GWAS) have detected an association with markers on chromosome 8q24. Allele -8 of microsatellite DG8S737 with 22 repeats and allele A of the single-nucleotide polymorphism (SNP) rs1447295 have been found to be significantly associated with prostate cancer. As GWAS are subjected to type 1 error, confirmation studies are required to validate the results. Here, we analysed the same markers in 277 cases and 282 controls from the Netherlands using a nested case-control study. Incident prostate cancer cases and controls selected were identified in the population of the Netherlands Cohort Study. We also investigated clinical features of the disease by stratifying by tumour stage. We did not replicate the association with the SNP rs1447295-A allele (P=0.10), although the effect estimate was in the same direction as previous studies (odds ratio (OR), 1.38). Interestingly a statistically significant decreased risk was observed for DG8S737 allele -8 (OR, 0.62; P=0.03). The apparent protective effect of the DG8S737 -8 allele observed in this study contrasts with the Amundadottir study. This suggests that DG8S737 and rs1447295 might be tightly linked markers flanking the actual causative variant and that there may be potentially more than one high-risk haplotype present in the Caucasian population. This short report highlights the importance of validation, although further confirmation is still needed.

HLA DPA1, DPB1 Alleles and Haplotypes Contribute to the Risk Associated With Type 1 Diabetes

OBJECTIVETo determine the relative risk associated with DPA1 and DPB1 alleles and haplotypes in type 1 diabetes.RESEARCH DESIGN AND METHODSThe frequency of DPA1 and DPB1 alleles and haplotypes in type 1 diabetic patients was compared to the family based control frequency in 1,771 families directly and conditional on HLA (B)-DRB1-DQA1-DQB1 linkage disequilibrium. A relative predispositional analysis (RPA) was performed in the presence or absence of the primary HLA DR-DQ associations and the contribution of DP haplotype to individual DR-DQ haplotype risks examined.RESULTSEight DPA1 and thirty-eight DPB1 alleles forming seventy-four DPA1-DPB1 haplotypes were observed; nineteen DPB1 alleles were associated with multiple DPA1 alleles. Following both analyses, type 1 diabetes susceptibility was significantly associated with DPB1*0301 (DPA1*0103-DPB1*0301) and protection with DPB1*0402 (DPA1*0103-DPB1*0402) and DPA1*0103-DPB1*0101 but not DPA1*0201-DPB1*0101. In addition, DPB1*0202 (DPA1*0103-DPB1*0202) and DPB1*0201 (DPA1*0103-DPB1*0201) were significantly associated with susceptibility in the presence of the high risk and protective DR-DQ haplotypes. Three associations (DPB1*0301, *0402, and *0202) remained statistically significant when only the extended HLA-A1-B8-DR3 haplotype was considered, suggesting that DPB1 alone may delineate the risk associated with this otherwise conserved haplotype.CONCLUSIONSHLA DP allelic and haplotypic diversity contributes significantly to the risk for type 1 diabetes; DPB1*0301 (DPA1*0103-DPB1*0301) is associated with susceptibility and DPB1*0402 (DPA1*0103-DPB1*0402) and DPA1*0103-DPB1*0101 with protection. Additional evidence is presented for the susceptibility association of DPB1*0202 (DPA1*0103-DPB1*0202) and for a contributory role of individual amino acids and DPA1 or a gene in linkage disequilibrium in DR3-DPB1*0101 positive haplotypes.

Necrotizing meningoencephalitis of Pug Dogs associates with dog leukocyte antigen class II and resembles acute variant forms of multiple sclerosis

Necrotizing meningoencephalitis (NME) is a disorder of Pug Dogs that appears to have an immune etiology and high heritability based on population studies. The present study was undertaken to identify a genetic basis for the disease. A genome-wide association scan with single tandem repeat (STR) markers showed a single strong association near the dog leukocyte antigen (DLA) complex on CFA12. Fine resolution mapping with 27 STR markers on CFA12 further narrowed association to the region containing DLA-DRB1, -DQA1 and, -DQB1 genes. Sequencing confirmed that affected dogs were more likely to be homozygous for specific alleles at each locus and that these alleles were linked, forming a single high risk haplotype. The strong DLA class II association of NME in Pug Dogs resembles that of human multiple sclerosis (MS). Like MS, NME appears to have an autoimmune basis, involves genetic and nongenetic factors, has a relatively low incidence, is more frequent in females than males, and is associated with a vascularly orientated nonsuppurative inflammation. However, NME of Pug Dogs is more aggressive in disease course than classical human MS, appears to be relatively earlier in onset, and involves necrosis rather than demyelination as the central pathobiologic feature. Thus, Pug Dog encephalitis (PDE) shares clinical features with the less common acute variant forms of MS. Accordingly, NME of Pug Dogs may represent a naturally occurring canine model of certain idiopathic inflammatory disorders of the human central nervous system.

No association of dysbindin with symptom factors of schizophrenia in an Irish case–control sample

Robust associations between the dysbindin gene (DTNBP1) and schizophrenia have been demonstrated in many but not all samples, and evidence that this gene particularly predisposes to negative symptoms in this illness has been presented. The current study sought to replicate the previously reported negative symptom associations in an Irish case-control sample. Association between dysbindin and schizophrenia has been established in this cohort, and a factor analysis of the assessed symptoms yielded three factors, Positive, Negative, and Schneiderian. The sequential addition method was applied using UNPHASED to assess the relationship between these symptom factors and the high-risk haplotype. No associations were detected for any of the symptom factors indicating that the dysbindin risk haplotype does not predispose to a particular group of symptoms in this sample. Several possibilities, such as differing risk haplotypes, may explain this finding.

Genetic Risk Markers Related to Diabetes-Associated Autoantibodies in Young Patients with Type 1 Diabetes in Berlin, Germany

To determine the prevalence of genetic risk markers of type 1 diabetes (T1D) in children diagnosed at a single centre in Germany and to assess their relation to diabetes-associated autoantibodies. Blood samples from 243 paediatric patients were genotyped for the high-risk HLA haplotypes DR3-DQ2 (DQA1*05-DQB1*02) and DR4-DQ8 (DRB1*0401/2/4/5-DQB1*0302) and PTPN22 C1858 T polymorphism. The patients (51.4% male) were diagnosed with T1D at a median age of 8.6 y. The T1D-related autoantibodies GADA, IAA and IA-2A were analysed at diagnosis. 166 patients (68.6%) carried the DR3-DQ2, 114 (47.1%) the DR4-DQ8 haplotype, while 41 (16.9%) patients were negative for both. The PTPN22 CC genotype was detected in 177 (72.8%), CT in 58 (23.9%) and TT in eight (3.3%) patients, respectively. The prevalence of T1D-related autoimmunity was 77.0% for IA-2A, 71.6% for GADA and 43.6% for IAA. There were no differences between patients with and without the 1858 T allele in terms of the frequency, levels or number of autoantibodies, but the former were younger at diagnosis than the latter (p=0.002), IA-2A were positively related to HLA DR4-DQ8 (p=0.004) and inversely associated with HLA DR3-DQ2 (p=0.002). GADA-positive patients were older than those without GADA (p=0.004). In multivariate logistic regression analysis including gender and age as confounding variables, DR4-DQ8 (OR 2.56, 95%CI 1.35-4.86) and DR3-DQ2 (OR 0.36, 95%CI 0.19-0.68) were the only independent predictors of IA-2A positivity. The prevalence of genetic risk markers in Berlin children with T1D is found to be comparable to other Caucasian T1D populations. The presence of IA-2A at diagnosis is strongly associated with the HLA risk haplotypes, but not with PTPN22 polymorphism.

Genetic variation within the HLA class III influences T1D susceptibility conferred by high-risk HLA haplotypes

HLA class II DRB1 and DQB1 represent the major type 1 diabetes (T1D) genetic susceptibility loci; however, other genes in the HLA region are also involved in T1D risk. We analyzed 1411 pedigrees (2865 affected individuals) from the type 1 diabetes genetics consortium (T1DGC) genotyped for HLA classical loci and for 12 SNPs in the class III region previously shown to be associated with T1D in a subset of 886 pedigrees. Using the transmission disequilibrium test, we compared the proportion of SNP alleles transmitted from within the high risk DR3 and DR4 haplotypes to affected offspring. Markers rs4151659 (mapping to CFB) and rs7762619 (mapping 5′ of LTA) were the most strongly associated with T1D on DR3 (p=1.2 × 10−9 and p=2 × 10−12 respectively) and DR4 (p=4 × 10−15 and p= 8 × 10−8 respectively) haplotypes. They remained significantly associated after stratifying individuals in analyses for B*1801, A*0101-B*0801, DPB1*0301, DPB1*0202, DPB1*0401 or DPB1*0402. Rs7762619 and rs4151659 are in strong linkage disequilibrium (LD) (r2=0.82) with each other, but a joint analysis showed that the association for each SNP was not solely due to LD. Our data support a role for more than one locus in the class III region contributing to risk of T1D.

Association analysis of the PIP4K2A gene on chromosome 10p12 and schizophrenia in the Irish study of high density schizophrenia families (ISHDSF) and the Irish case–control study of schizophrenia (ICCSS)

Molecular studies support pharmacological evidence that phosphoinositide signaling is perturbed in schizophrenia and bipolar disorder. The phosphatidylinositol-4-phosphate-5-kinase type-II alpha (PIP4K2A) gene is located on chromosome 10p12. This region has been implicated in both diseases by linkage, and PIP4K2A directly by association. Given linkage evidence in the Irish Study of High Density Schizophrenia Families (ISHDSF) to a region including 10p12, we performed an association study between genetic variants at PIP4K2A and disease. No association was detected through single-marker or haplotype analysis of the whole sample. However, stratification into families positive and negative for the ISHDSF schizophrenia high-risk haplotype (HRH) in the DTNBP1 gene and re-analysis for linkage showed reduced amplitude of the 10p12 linkage peak in the DTNBP1 HRH positive families. Association analysis of the stratified sample showed a trend toward association of PIP4K2A SNPs rs1417374 and rs1409395 with schizophrenia in the DTNBP1 HRH positive families. Despite this apparent paradox, our data may therefore suggest involvement of PIP4K2A in schizophrenia in those families for whom genetic variation in DTNBP1 appears also to be a risk factor. This trend appears to arise from under-transmission of common alleles to female cases. Follow-up association analysis in a large Irish schizophrenia case-control sample (ICCSS) showed significant association with disease of a haplotype comprising these same SNPs rs1417374-rs1409395, again more so in affected females, and in cases with negative family history of the disease. This study supports a minor role for PIP4K2A in schizophrenia etiology in the Irish population.

Schizophrenia-Related Neuregulin-1 Single-Nucleotide Polymorphisms Lead to Deficient Smooth Eye Pursuit in a Large Sample of Young Men

Neuregulin-1 (NRG1) variations have been shown to modulate schizophrenia candidate endophenotypes related to brain structure and function. The aim of this study was to determine the effect of NRG1 on several oculomotor schizophrenia endophenotypes. The effects of 5 core single-nucleotide polymorphisms (SNPs) within the NRG1 gene to oculomotor parameters in a battery of oculomotor tasks (saccade, antisaccade, smooth eye pursuit, fixation) were investigated in a sample of 2243 young male military conscripts. Additive regression models, bootstrap and permutation techniques, were used as well as structural equation modeling and haplotype analysis. A deficit in global smooth eye pursuit performance measured using the root-mean-square error (RMSE) was related to the risk allele of SNP8NRG243177, and a deficit in global smooth eye pursuit performance measured using the saccade frequency was related with the risk allele of SNP8NRG433E1006. Structural equation modeling confirmed a global effect of NRG1 genotype on smooth eye pursuit performance using the RMSE, while the effect on saccade frequency was not confirmed. Haplotype analysis further confirmed the prediction from the structural equation modeling that a combination of alleles corresponding to the Icelandic high-risk haplotype was related to a deficit in global pursuit performance. NRG1 genotype variations were related to smooth eye pursuit variations both at the SNP level and at the haplotype level adding to the validation of this gene as a candidate gene for the disorder.

Association of HLA class I alleles with keloids in Chinese Han individuals

Keloids are benign fibroproliferative dermal tumors of unknown etiology. Some studies have suggested that human HLA status might potentiate development of keloids phenotype. No report has been published about HLA class I alleles associated with keloids in Chinese Han individuals. To investigate the etiology of keloids, the polymerase chain reaction–sequence-specific primer (PCR-SSP) method was used to analyze the distribution of HLA class I alleles in 192 patients with keloids and 252 healthy controls in a Chinese Han population. The frequencies of HLA-A*03 (6.77% vs 0%, p c < 10 −7), A*25 (10.16% vs 4.56%, p c = 0.0111), B*07 (7.81% vs 2.58%, p c = 0.0080), and Cw*0802 (19.79% vs 10.32%, p c = 0.0004) were significantly increased in keloid patients, whereas the frequency of HLA-A*01 (18.75% vs 38.10%, p c < 10 −7) was highly decreased, compared with that in healthy controls. The A*03-B*07, A*25-B*07, A*03-Cw*0802, A*25-Cw*0802, and B*07-Cw*0802 were found as high-risk haplotypes in developing keloids in this study. No extended haplotype was found to be significantly related to keloids. Through stratified analysis, the association of subgroups (single site/multiple site, severity, and family history) of keloid patients with specific HLA alleles was identified. Our data suggest these alleles may be keloids susceptibility genes or may be in close linkage with the susceptibility genes.

Detecting Genes and Gene–Gene Interactions for Age-Related Macular Degeneration with a Forest-based Approach

Age-related macular degeneration (AMD) is a leading cause of vision loss in the elderly. Genetic mechanisms underlying AMD are complex. Understanding the etiology of AMD is important because of the significant health and social concerns. In this article, we describe a forest-based approach to systematically identifying multiple genes, gene–gene interactions, and gene–environment interactions underlying complex diseases in genome-wide case-control studies and the application of this approach to a published dataset on AMD. Our analysis not only confirmed two known haplotypes, ACTCCG (on chromosome 1 with a p-value of 1.98e-6) and TCTGGACGACA (on chromosome 7 with a p-value of 9.81e-3), but also revealed two novel haplotypes, GATAGT (on chromosome 5 with a p-value of 3.46e-3) and TCTTACGTAGA (on chromosome 12 with a p-value of 3.16e-2). Thus, the significance of this work is two-fold. First, we propose a powerful and robust method to identify high-risk haplotypes and their interactions; second, we reveal potential genetic variants associated with AMD.

Effect of the G72 (DAOA) putative risk haplotype on cognitive functions in healthy subjects

BackgroundIn the last years, several susceptibility genes for psychiatric disorders have been identified, among others G72 (also named D-amino acid oxidase activator, DAOA). Typically, the high-risk variant of a vulnerability gene is associated with decreased cognitive functions already in healthy individuals. In a recent study however, a positive effect of the high-risk variant of G72 on verbal working memory was reported. In the present study, we therefore examined the relationship between G72 genotype status and a broad range of cognitive functions in 423 healthy individuals.MethodsThe G72 carrier status was assessed by the two single nucleotide polymorphisms (SNPs) M23 and M24. Subjects were divided into three risk groups (low, intermediate and high risk).ResultsG72 status influenced a number of cognitive functions, such as verbal working memory, attention, and, at a trend level, spatial working memory and executive functions. Interestingly, the high-risk allele carriers scored better than one or even both other groups.ConclusionOur data show that the putative high-risk haplotype (i.e. homozygote C/C-allele carriers in SNP M23 and homozygote T/T-allele carriers in SNP M24) is in healthy individuals not necessarily associated with worse performance in cognitive functions, but even with better performance in some domains. Further work is required to identify the mechanisms of G72 on brain functions.

Altering the Relative Abundance of GABAA Receptor Subunits Changes GABA‐ and Ethanol‐Responses in Xenopus Oocytes

Variations in GABRA2 and GABRG3, genes encoding the alpha2 and gamma3 subunits of the pentameric GABA(A) receptor, are associated with the risk of developing alcoholism in adults, conduct disorder at younger ages, and with differences in electroencephalographic power in the beta frequency range. The SNPs associated with alcoholism did not alter the coding of these genes, and extensive DNA sequencing of GABRA2 did not find coding changes in the high-risk haplotypes. Therefore, we hypothesize that the associations arise from differences in gene expression. Here we report studies in Xenopus oocytes to examine the functional effects of altering the relative abundance of these 2 receptor subunits on GABA current and response to ethanol, as a model of potential effects of regulatory differences. When human alpha2beta2gamma3 subunits are co-expressed, increasing the amount of the alpha2 subunit mRNA increased GABA current; in contrast, increasing the amount of the gamma3 subunit decreased GABA currents. Acute ethanol treatment of oocytes injected with a 1:1:1 or 2:2:1 ratio of alpha2:beta2:gamma3 subunit mRNAs resulted in significant potentiation of GABA currents, whereas ethanol inhibited GABA currents in cells injected with a 6:2:1 ratio. Overnight treatment with ethanol significantly reduced GABA currents in a manner dependent on the ratio of subunits. These studies demonstrate that changes in relative expression of GABA(A) receptor subunits alter the response of the resulting channels to GABA and to ethanol.

Polymorphisms of CXCR3-binding chemokines in type 1 diabetes

Type 1 diabetes (T1D) is a T-cell–mediated autoimmune disease. Although the precise mechanisms leading to the destruction of islet β cells are unknown, diverse studies support a role of the CXCR3-binding chemokines. A combination of a case ( n = 447)–control ( n = 300) and family ( n = 221) analysis was performed to investigate the role of the CXCL9 (rs10336, rs3733236) and CXCL10 (rs3921, rs35795399 and rs8878) polymorphisms and their interaction with HLA high-risk haplotypes DQ2(DQA*0501-DQB*0201)-DQ8(DQA*0301-DQB*0302) in T1D. In addition, the mRNA expression of these genes and of the CXCR3 in peripheral blood mononuclear cells (PBMCs) of T1D patients was studied. In the family analysis, an overtransmission of the allele T and G of the polymorphisms rs35795399 and rs8878 in the whole group ( p = 0.0520 and p = 0.0290, respectively) as well as in combination with the HLA-high risk haplotypes ( p = 0.0209 and 0.0340, respectively) were observed. In addition, the haplotype rs8878G-rs35795399T was more often transmitted from parents to affected offspring, whereas the haplotype rs8878A-rs35795399C was less often transmitted ( p = 0.0130 and p = 0.0201, respectively). Nevertheless these associations did not remain significant after correction for multiple testing, and they could not be corroborated in the case-control analysis. Although we did not find an association of the CXCL9 and CXCL10 polymorphisms with type 1 diabetes in the German population, we cannot discard their role in other populations or other autoimmune diseases.