Catechol-O-methyltransferase gene polymorphisms are associated with multiple pain-evoking stimuli

Variations in the gene encoding catechol-O-methyltransferase (COMT) are linked to individual differences in pain sensitivity. A single nucleotide polymorphism (SNP) in codon 158 (val(158)met), which affects COMT protein stability, has been associated with the human experience of pain. We recently demonstrated that three common COMT haplotypes, which affect the efficiency of COMT translation, are strongly associated with a global measure of pain sensitivity derived from individuals' responses to noxious thermal, ischemic, and pressure stimuli. Specific haplotypes were associated with low (LPS), average (APS), or high (HPS) pain sensitivity. Although these haplotypes included the val(158)met SNP, a significant association with val(158)met variants was not observed. In the present study, we examined the association between COMT genotype and specific pain-evoking stimuli. Threshold and tolerance to thermal, ischemic, and mechanical stimuli, as well as temporal summation to heat pain, were determined. LPS/LPS homozygotes had the least, APS/APS homozygotes had average, and APS/HPS heterozygotes had the greatest pain responsiveness. Associations were strongest for measures of thermal pain. However, the rate of temporal summation of heat pain did not differ between haplotype combinations. In contrast, the val(158)met genotype was associated with the rate of temporal summation of heat pain, but not with the other pain measures. This suggests that the val(158)met SNP plays a primary role in variation in temporal summation of pain, but that other SNPs of the COMT haplotype exert a greater influence on resting nociceptive sensitivity. Here, we propose a mechanism whereby these two genetic polymorphisms differentially affect pain perception.     

An association study of asthma and related phenotypes with polymorphisms in negative regulator molecules of the TLR signaling pathway

Although associations between endotoxin exposure or respiratory infection and asthma have been recognized, the genetic effects in these conditions are unclear. Toll-like receptors (TLRs) play an essential role in innate host defense and in the control of adaptive immune responses. IL-1R-associated kinase-M (IRAK-M) and single immunoglobulin IL-1R-related molecule (SIGIRR) negatively regulate TLR-signaling pathways. To investigate whether polymorphisms in these genes were associated with asthma or asthma-related phenotypes, we screened these genes for polymorphisms by direct sequencing of 24 asthmatics and identified 19 variants in IRAK-M and 12 variants in SIGIRR. We next conducted linkage disequilibrium mapping of the genes, and examined the association of polymorphisms and haplotypes using 391 child patients with asthma, 462 adult patients with asthma, and 639 controls. None of the alleles or haplotypes of IRAK-M and SIGIRR were associated with asthma susceptibility or asthma-related phenotype. Our results indicate that polymorphisms in IRAK-M and SIGIRR are not likely to be associated with the development of asthma in the Japanese population.Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users.     

Association between gene polymorphisms of SLC22A3 and methamphetamine use disorder

BACKGROUND: Methamphetamine (MAP) is one of the most frequently used illegal substances in Japan, and family and twin studies have suggested that genetic factors contribute to psychostimulant dependence, including MAP dependence. Organic cation transporter 3 (OCT3) has been reported to be involved in the disposition of MAP as well as MAP-induced behavioral changes in animals. Moreover, SLC22A3 (which encodes OCT3) is a candidate gene for MAP dependence because it is located within a chromosomal region associated with substance dependence. METHODS: Using 96 healthy control subjects, linkage disequilibrium (LD) within the SLC22A3 was investigated, and 5 single-nucleotide polymorphisms (SNPs) were selected as haplotype tag SNPs to search for an association with MAP dependence. Single-marker analyses and haplotype analyses of these SNPs were performed in 213 subjects with MAP dependence and 443 healthy controls. RESULTS: SLC22A3 polymorphisms were not significantly associated with MAP dependence in any of the single-marker and haplotype analyses. When subjects with MAP dependence were divided into polysubstance and single-MAP users, genotype and allele frequency of SNP2 (p=0.024, p=0.011, respectively), allele frequency of SNP3 (p=0.037), and haplotypic frequencies for these 2 SNPs (p=0.0438) differed significantly between groups. CONCLUSIONS: These results suggest that polymorphisms of SLC22A3 are related to the development of polysubstance use in Japanese patients with MAP dependence.     

Positive association of the <Emphasis Type="Italic">FTSJ1</Emphasis> gene polymorphisms with nonsyndromic X-linked mental retardation in young Chinese male subjects

To investigate the possible genetic association of nonsyndromic X-linked mental retardation (NS-XLMR) with FTSJ1 gene polymorphisms, a case-control association study was performed focusing on the Chinese Han population in the Qinba mountain region. Three common single nucleotide polymorphisms (SNPs) (rs2268954, rs2070991, rs5905692) in the gene were selected and genotyped using the polymerase chain reaction single-strand confirmation polymorphism (PCR-SSCP) method. Pairwise linkage disequilibrium (LD) analysis showed that the three SNPs were in strong LD (all D' > 0.8). There were significant differences between cases and controls in allele frequency distribution of rs2268954 (P = 0.036), rs2070991 (P = 0.043), and rs5905692 (P = 0.014) and in the distributions of common haplotypes combined by these SNPs (global P = 0.01236) in male subjects. In female subjects, however, no positive results were found. Our results suggest a positive association between the genetic variants of the FTSJ1 gene and NS-XLMR in young male subjects in the Chinese Han population in the Qinba region.     

New correction algorithms for multiple comparisons in case–control multilocus association studies based on haplotypes and diplotype configurations

The multiple comparison problem arises in population-based studies when the association between phenotypes and multilocus genotypes is examined. Although Bonferroni’s correction is often used to cope with such a problem, it may yield too conservative conclusions because all of the tests are assumed to be independent. We have developed new correction algorithms for the test of independence between phenotypes and multilocus genotypes at loci in linkage disequilibrium. In one of the algorithms, the exact type I error rate is calculated for the independency test. We found that such exact probabilities can be calculated using a 128 CPU PC cluster if the numbers of cases and controls are not more than 50. As an alternative method, we developed algorithms to calculate asymptotically the type I error rates using a Markov-chain Monte Carlo sampler that provided a good approximation to values calculated by the exact method. When the new algorithms were applied to both simulation and real data, the real overall type I error rates for the loci in linkage disequilibrium were from one-third to half as high as those obtained by Bonferroni’s correction. These algorithms are likely to be useful for multilocus association studies for data obtained by case–control and cohort studies.     

A common variation in the cannabinoid 1 receptor (CNR1) gene is associated with pre-eclampsia in the Central European population

Objective

Recently it has been proposed that tightly regulated levels of endogenous cannabinoids play a fundamental role in early placental development. The aim of this study was to investigate associations of three single-nucleotide polymorphisms (SNPs) in the cannabinoid 1 receptor (CNR1) gene (rs1049353, rs12720071 and rs806368) and their inferred haplotypes with pre-eclampsia, a severe pregnancy-associated condition characterized by abnormal development and remodeling of spiral decidual arteries.

Study design

The case-control study comprised a total of 115 pre-eclamptic women and 145 healthy pregnant controls, all originating from the Central-European Czech population. Using PCR-based methods, we tested rs1049353, rs12720071 and rs806368 in the CNR1 gene and haplotypes were constructed.

Results

Statistically significant difference in genotype distributions of rs806368 (p_g < 10⁻³) was observed when comparing the cases and the controls; the cases presenting with significantly lower proportion of CC homozygotes. In multivariate modeling, the rs806368 served as a predictor for pre-eclampsia development (β = 0.15; p = 0.04). Haplotype analysis revealed presence of four common haplotypes; the CAA haplotype being less frequent in pre-eclamptic cases compared to the controls (p < 0.008). Analysis of regression models confirmed the independent prediction role of AAC haplotype for pre-eclampsia onset (β = −0.18; p = 0.03).

Conclusion

This is the first study focusing on the relationship between SNPs in the CNR1 gene and pre-eclampsia risk. Although limited by a relatively small sample size, the study indicates that rs806368 in the CNR1 gene may act as a susceptibility marker for pre-eclampsia in humans.     

5个X染色体STR基因座的群体遗传学分析

目的 调查苏州汉族群体中5个X-STR的等位基因和单倍型分布,以及分析这些基因座间的连锁不平衡关系.方法 应用Chelex法提取样本DNA,PCR扩增5个X-STR,应用自动测序仪对PCR产物进行分型.结果 苏州汉族群体中,DXS7423、DXS10147、DXS10146、DXS10134、DXS8377分别观察到5、6、15、21、15个等位基因;男女性样本间,DXS7423、DXS10147、DXS10134的等位基因频率差异无统计学意义,P值分别为0.161、0.756、0.179;DXS10146、DXS8377等位基因频率差异具有统计学意义,P值分别为0.008和0.005.5个X-STR的观察杂合度在0.505～0.845间,DPf值在0.684～0.977间,DPm值在0.487 ～0.902间,MCEtrio值在0.469～0.894间,MCEduo值在0.266～0.860间.男性样本中,观察到111种单倍型,单倍型变异度为0.9916.结论 苏州汉族群体中,5个X-STR中DXS10146、DXS10134、DXS8377多态性较好;5个X- STR构成的单倍型鉴别能力较高.     

Association of MMP-8 promoter gene polymorphisms with carotid atherosclerosis: preliminary study

Objective

Matrix metalloproteinases (MMPs) are involved in the remodeling of the extracellular matrix in the arterial wall. Collagen I is associated with vascular smooth muscle cell (VSMC) migration and monocyte differentiation. MMP-8 is expressed in atherosclerotic plaque and preferentially cleaves collagen type I. The aim of this study was to investigate the associations of two MMP-8 promoter polymorphisms, rs11225395 (−799 C/T) and rs1320632 (−381 A/G), with carotid plaque occurrence, and the influence of these polymorphisms on MMP-8 mRNA expression in plaque tissue.

Methods

The study included a total of 766 participants: 277 controls and 489 patients with carotid atherosclerosis undergoing endarterectomy. The two investigated polymorphisms were genotyped by PCR-RFLP. The gene expression analysis was performed by real-time PCR.

Results

In females only, a significantly higher frequency of the −381G allele was found in patients with carotid atherosclerosis compared to controls (OR, 1.7; 95% CI 1.1–2.9; p = 0.001). Significant up-regulation of MMP-8 gene expression was observed in patients carrying the −381G allele compared to those with the AA genotype (mean factor, 3.54; S.E. range, 0.643–19.551; p = 0.007). Carotid plaque tissue of the haplotype G₋₃₈₁T₋₇₉₉ showed a significantly higher mRNA level compared with the reference A₋₃₈₁C₋₇₉₉ haplotype (p = 0.003).

Conclusion

Our preliminary results indicate that MMP-8 −381A/G and −799 C/T gene polymorphisms could be risk factors for carotid atherosclerosis. Further validation and functional studies are needed to establish the potential regulatory role of these polymorphisms and their impact on susceptibility to carotid atherosclerosis.