绝经后妇女MTHFR基因多态性位点联合作用与骨质疏松易感性的相关性分析

目的研究5,10亚甲基四氢叶酸还原酶(methylene tetrahydrofolate reductase,MTHFR)的2个多态性位点rs1801131 A1298C和rs1801133 C677T的联合作用与苏州地区绝经后妇女骨质疏松遗传易感性的相关性。方法对从苏州市城区随机抽取的261例45~70岁绝经后妇女进行流行病学调查、基础资料测量及桡骨远端骨密度测定,利用荧光定量PCR技术(TaqMan)进行基因分型。应用SAS 9.1.3统计软件进行统计分析,PHASE 2.0软件进行单倍型分析,应用广义多因子降维法(GMDR软件,version 0.7)检测位点-位点、位点-环境之间的联合作用。结果调整年龄、体质量指数(BMI)、腰臀比(WHR)及产次后,MTHFR基因rs1801133(C→T)的位点变异与骨质疏松的发生成正关联。与野生型rs1801133 CC基因型相比,突变纯合型rs1801133 TT及CT/TT型可以显著增加骨质疏松的发生风险[调整OR=2.63,2.37;95%CI=(1.20~5.77),(1.16~4.87)]。经1000次置换检验(Permutation test)方法校正后,该位点的基因型频率分布在病例组与对照组间仍存在统计学差异。单倍型分析结果显示,与最常见的单倍型CC相比,含突变等位基因rs1801131 A的单倍型AC可以显著降低绝经后妇女骨质疏松的患病风险[调整OR=0.60;95%CI=(0.39~0.90)]。广义多因子降维法结果显示,模型A1 A2(rs1801131,rs1801133)为最佳模型(交叉验证一致性10/10,P=0.0107)。结论 MTHFR基因rs1801133位点多态性与苏州地区绝经后妇女骨质疏松的发病风险存在明显关联;rs1801131位点可能与rs1801133位点产生联合作用,共同影响绝经后妇女骨质疏松的发生风险。     

Dissociation between APOC3 variants, hepatic triglyceride content and insulin resistance

Nonalcoholic fatty liver disease (NAFLD) is an escalating health problem that is frequently associated with obesity and insulin resistance. The mechanistic relationship between NAFLD, obesity, and insulin resistance is not well understood. A nonsynonymous variant in patatin-like phospholipase domain containing 3 (rs738409, I148M) has been reproducibly associated with increased hepatic triglyceride content (HTGC) but has not been associated with either the body mass index (BMI) or indices of insulin resistance. Conversely, two sequence variants in apolipoprotein C3 (APOC3) that have been linked to hypertriglyceridemia (rs2854117 C > T and rs2854116 T > C) have recently been reported to be associated with both hepatic fat content and insulin resistance. Here we genotyped two APOC3 variants in 1228 African Americans, 843 European Americans and 426 Hispanics from a multiethnic population based study, the Dallas Heart Study and test for association with HTGC and homeostatic model of insulin resistance (HOMA-IR). We also examined the relationship between these two variants and HOMA-IR in the Atherosclerosis Risk in Communities (ARIC) study. No significant difference in hepatic fat content was found between carriers and noncarriers in the Dallas Heart Study. Neither APOC3 variant was associated with HOMA-IR in the Dallas Heart Study; this lack of association was confirmed in the ARIC study, even after the analysis was restricted to lean (BMI < 25 kg/m(2) ) individuals (n = 4399). CONCLUSION: Our data do not support a causal relationship between these two variants in APOC3 and either HTGC or insulin resistance in middle-aged men and women.     

Cholesteryl ester transfer protein gene polymorphisms increase the risk of fatty liver in females independent of adiposity

Background and Aim: Environmental factors including excessive caloric intake lead to disordered lipid metabolism and fatty liver disease (FLD). However, FLD demonstrates heritability suggesting genetic factors are also important. We aimed to use a candidate gene approach to examine the association between FLD and single nucleotide polymorphisms (SNPs) in lipid metabolism genes in the adolescent population‐based Western Australian Pregnancy (Raine) Cohort. Methods: A total 951 seventeen year‐olds underwent hepatic ultrasound, anthropometric and biochemical characterization, DNA extraction and genotyping for 57 SNPs in seven lipid metabolism genes (ApoB100, ATGL, ABHD5, MTTP, CETP, SREBP‐1c, PPARα). Associations were adjusted for metabolic factors and Bonferroni corrected. Results: The prevalence of FLD was 16.2% (11.4% male vs 21.2% female, P = 0.001). Multivariate analysis of metabolic factors found suprailiac skinfold thickness (SST) to be the major predictor of FLD in females and males (odds ratio [OR] 1.11, 95% confidence interval [CI] 1.08‐1.15, P = 1.7 × 10^?10 and OR 1.17, 95%CI 1.13–1.22, P = 2.4 × 10^?11, respectively). In females, two SNPs in linkage disequilibrium from the CETP gene were associated with FLD: rs12447924 (OR 2.16, 95%CI 1.42–3.32, P = 0.0003) and rs12597002 (OR = 2.22, 95%CI 1.46–3.41 P = 0.0002). In lean homozygotes, the probability of FLD was over 30%, compared with 10–15% in lean heterozygotes and 3–5% in lean wild‐types. However, these associations were modified by SST, such that for obese individuals, the probability of FLD was over 30% in all genotype groups. Conclusions: Cholesteryl ester transfer protein gene polymorphisms are associated with an increased risk of FLD in adolescent females. The effect is independent of adiposity in homozygotes, thereby placing lean individuals at a significant risk of FLD.     

胰腺癌细胞DPYD、MTHFR基因单核苷酸多态性分析

目的检测胰腺癌（PC）细胞株中两种代谢相关基因的单核苷酸多态性（SNPs）,为临床预测氟尿嘧啶类药物的疗效及毒副反应提供参考依据。方法培养PANC-1、CFPAC、SW1990三株PC细胞,采用QIAamp DNABlood Minikit试剂盒提取基因组DNA,用基质辅助激光解吸电离飞行时间质谱技术行二氢嘧啶脱氢酶基因（DPYD）rs1801159、rs1801160、rs17376848,亚甲基四氢叶酸还原酶（MTHFR）基因rs2274976、rs1801131、rs1801133的SNPs位点检测。结果三种PC细胞株的DPYD基因rs1801159位点基因型均为A/A纯合子,rs1801160位点基因型均为G/G。CFPAC细胞株DPYD基因的rs17376848位点基因型为A/G,PANC-1、SW1990细胞株的rs17376848位点基因型为A/A纯合子。PANC-1、CFPAC细胞MTHFR基因的rs1801131位点基因型为A/C杂合子,rs1801133位点基因型为C/C;SW1990细胞株MTHFR基因的rs1801131位点基因型为A/A纯合子,rs1801133位点基因型为T/T纯合子;三株细胞MTHFR基因的rs2274976基因型位点均为G/G纯合子。结论本实验所测三株PC细胞的DPYD基因rs1801159、rs1801160位点、MTHFR基因rs2274976位点基因型相同,其余各位点基因型均不完全相同。     

Associations between methylenetetrahydrofolate reductase polymorphisms and hepatocellular carcinoma risk: An update meta-analysis and trial sequential analysis

Aim:To evaluate the associations between the methylenetetrahydrofolate reductase (MTHFR) single-nucleotide polymorphisms (SNPs) and hepatocellular carcinoma (HCC) with meta-analysis and trial sequential analysis.Methods:PubMed, Embase, the Google Scholar, Wan fang database, VIP database, and China National Knowledge Infrastructure were extensively searched before April 2021. Odds ratios (ORs) and 95% confidence interval (95% CI) were calculated. Review Manager Version 5.3, STATA version 12.0 and TSA 0.9.5.10 Beta software were used.Results:Nineteen studies with 6941 HCC patients and 9436 controls were finally included. The MTHFR rs1801133 (C677T) SNP was associated with increased HCC risk under heterozygote genetic model (OR = 1.10, 95% CI = [1.01, 1.20]). For Subgroup analysis, increased risks of HCC were detected in Mongoloid, Chinese. For MTHFR rs1801131 (A1298C) SNP, increased risk of HCC was only observed in Caucasians (allelic: OR = 1.86, 95% CI = [1.49, 2.31]; homozygote: OR = 3.39, 95% CI = [2.18, 5.27]), interesting decreased risk was detected in Mongoloid (recessive: OR = 0.30, 95% CI = [0.15, 0.58]; homozygote: OR = 0.41, 95% CI = [0.24, 0.72]). Sensitivity analysis indicated stability in our results. Publication bias was not detected based on Begg test and Egger test. Trial sequential analysis indicated further studies to confirm the associations in MTHFR C677T polymorphism.Conclusion:The MTHFR rs1801133 SNP was associated with an increased risk of HCC in Mongoloid population especially in Chinese. Increased HCC risk is also observed in Caucasian population for the MTHFR rs1801131 SNP, and decreased risk of HCC is remarkably discovered in Mongoloid and Chinese subgroups, which need further validation.     

Population distribution of methylenetetrahydrofolate reductase (MTHFR) C677T and A1298C risk alleles for methotrexate toxicity in Israel

Methylenetetrahydrofolate reductase (MTHFR) is a central regulatory enzyme in the folate pathway. Two non-synonymous single nucleotide polymorphisms in MTHFR, C677T (rs1801133) and A1298C (rs1801131) have been associated with reduced MTHFR enzyme activity. These polymorphisms, especially C677T, appear to be linked with methotrexate-related toxicity, particularly hepatotoxicity; thus, pretreatment identification of individuals carrying these polymorphisms may be of clinical relevance. The purpose of this study was to determine the frequency and distribution of MTHFR polymorphic variants, known to functionally impair MTHFR activity, in the highly heterogeneous Israeli population. MTHFR genotyping was carried out in the representatives of three major demographic groups in Israel by PCR–restriction fragment length polymorphism and high-resolution melting. The relative distribution of variant alleles 677T and 1298C was found to be similar in individuals of Jewish, Druze and Arab Moslem descent (p = 0.09). However, Ashkenazi Jews displayed a 1.9-fold higher frequency of variant 677T and a 1.8-fold lower frequency of variant 1298C compared to non-Ashkenazi Jews (p < 0.001). Distinct differences in the relative frequencies of both polymorphisms were also found between Ashkenazi Jews and Druze (p < 0.01 for C677T, p < 0.01 for A1298C) or Ashkenazi Jews and Arab Moslem (p < 0.01 for C677T, p < 0.05 for A1298C). These data underscore the importance of geographic genetic analysis for a better understanding of human pharmacotherapy and personalized medicine.     

Associations of 25 structural,degradative, and inflammatory candidate genes with lumbar disc desiccation,bulging, and height narrowing

Objective

To examine the allelic diversity of structural, inflammatory, and matrix‐modifying gene candidates and their association with disc degeneration.

Methods

Subjects were 588 men ages 35–70 years. We investigated associations of single‐nucleotide polymorphisms in AGC1 and in 12 collagen, 8 interleukin, and 4 matrix metalloproteinase genes with quantitative magnetic resonance imaging measurements of disc desiccation and disc bulging and height narrowing scores, after controlling for age and suspected risk factors. Analyses were performed using QTDT software. P values were derived from 1,000 permutations, and empirical P values for global significance also were applied.

Results

Twelve of the 99 variants in 25 selected candidate genes provided evidence of association (P < 0.05) with disc signal intensity in the upper and/or lower lumbar regions. Allelic variants of AGC1 (rs1042631; P = 0.001), COL1A1 (rs2075555; P = 0.005), COL9A1 (rs696990; P = 0.00008), and COL11A2 (rs2076311; P = 0.018) genes provided the most significant evidence of association with disc signal intensity. The same variants of AGC1 (P = 0.010) and COL9A1 (P = 0.014), as well as variants in the COL11A1 gene (rs1463035 [P = 0.004]; rs1337185 [P = 0.015]) were also associated with disc bulging, as was AGC1 with disc height narrowing (rs1516797; P = 0.005). In addition, 4 allelic variants in the immunologic candidate genes (rs2071375 in IL1A [P = 0.027]; rs1420100 in IL18RAP [P = 0.005]) were associated with disc signal intensity.

Conclusion

Genetic variants account for interindividual differences in disc matrix synthesis and degradation. The accuracy of the quantitative disc signal intensity measurements we used likely enhanced our ability to observe these associations. Our findings shed light on possible mechanisms of degeneration and support the view that disc degeneration is a polygenetic condition.

     

Liver phenotypes in PCOS: Analysis of exogenous and inherited risk factors for liver injury in two European cohorts

Background & Aims

Fatty liver disease (FLD) is common in women with polycystic ovary syndrome (PCOS). Here, we use non-invasive tests to quantify liver injury in women with PCOS and analyse whether FLD-associated genetic variants contribute to liver phenotypes in PCOS.

Methods

Prospectively, we recruited women with PCOS and controls at two university centres in Germany and Poland. Alcohol abuse was regarded as an exclusion criterion. Genotyping of variants associated with FLD was performed using TaqMan assays. Liver stiffness measurements (LSM), controlled attenuation parameters (CAP) and non-invasive HSI, FLI, FIB-4 scores were determined to assess hepatic steatosis and fibrosis.

Results

A total of 42 German (age range 18–53 years) and 143 Polish (age range 18–40 years) women with PCOS, as well as 245 German and 289 Polish controls were recruited. In contrast to Polish patients, Germans were older, presented with more severe metabolic profiles and had significantly higher LSM (median 5.9 kPa vs. 3.8 kPa). In the German cohort, carriers of the PNPLA3 p.I148M risk variant had an increased LSM (p = .01). In the Polish cohort, the minor MTARC1 allele was linked with significantly lower serum aminotransferases activities, whereas the HSD17B13 polymorphism was associated with lower concentrations of 17-OH progesterone, total testosterone, and androstenedione (all p < .05).

Conclusions

FLD is common in women with PCOS. Its extent is modulated by both genetic and metabolic risk factors. Genotyping of variants associated with FLD might help to stratify the risk of liver disease progression in women suffering from PCOS.     

Association between genetic variants of the ADD1 and GNB3 genes and blood pressure response to the cold pressor test in a Chinese Han population: the GenSalt Study

Genetic factors influence blood pressure (BP) response to the cold pressor test (CPT), which is a phenotype related to hypertension risk. We examined the association between variants of the α-adducin (ADD1) and guanine nucleotide binding protein (G protein) β-polypeptide 3 (GNB3) genes and BP response to the CPT. A total of 1998 Han Chinese participants from the Genetic Epidemiology Network of Salt Sensitivity completed the CPT. The area under the curve (AUC) above the baseline BP during the CPT was used to measure the BP response. Twelve single-nucleotide polymorphisms (SNPs) of the ADD1 and GNB3 genes were selected and genotyped. Both single-marker and haplotype association analyses were conducted using linear mixed models. The rs17833172 and rs3775067 SNPs of the ADD1 gene and the rs4963516 SNP of the GNB3 gene were significantly associated with the BP response to CPT, even after adjusting for multiple testing. For the ADD1 gene, the AA genotype of SNP rs17833172 was associated with lower systolic BP (SBP) reactivity (P<0.0001) and faster BP recovery (P=0.0003). The TT genotype of rs3775067 was associated with slower SBP recovery (P=0.004). For the GNB3 gene, the C allele of SNP rs4963516 was associated with faster diastolic BP recovery (P=0.002) and smaller overall AUC (P=0.003). Haplotype analysis indicated that the CCGC haplotype of ADD1 constructed by rs1263359, rs3775067, rs4961 and rs4963 was significantly associated with the BP response to CPT. These data suggest that genetic variants of the ADD1 and GNB3 genes may have important roles in BP response to the CPT. Future studies aimed at replicating these novel findings are warranted.     

Association of GLUT4 gene variants with HbA1c level in Japanese men

GLUT4 is a major mediator of glucose removal from the circulation and a key regulator of whole-body glucose homeostasis. Recent studies in south Indian populations revealed that haplotypes of the GLUT4 gene associated with type 2 diabetes. A total of 734 middle aged apparently healthy Japanese men were recruited from two separate occupational cohorts from Kanagawa and Kyoto. Participants were genotyped for GLUT4 variants, rs5418 (A/G) and rs2654185 (C/A), and association with HbA1c level was analyzed. The HbA1c value was determined by JDS method which is 0.4% lower than NGSP value. The G allele carrier of rs5418 and A allele carrier of rs2654185 associated with significantly higher HbA1c level (AG + GG vs. AA carriers; 5.2 ± 0.8 vs. 4.9 ± 0.4, P < 0.002, and AA + AC vs. CC; 5.2 ± 0.9, vs. 4.9 ± 0.4, P < 0.002, respectively). G allele, AG + GG genotype of rs5418 and A allele, AA + AC genotype of rs2654185 showed a significant association with higher HbA1c (β = 0.215, P = 0.026; β = 0.215, P = 0.026; β = 0.190, P = 0.042; β = 0.190, P = 0.042, respectively). These two SNPs are in high linkage disequilibrium (LD) of r(2) = 0.67. In haplotype analysis, four haplotypes were estimated. HbA1c is significantly higher in the most frequent GA haplotype compared with the second frequent AC haplotype (5.2% vs. 5.1%, P = 0.004). Genetic variations, rs5418 and rs2654185 in GLUT4 gene are associated with HbA1c level in Japanese men.     

TCF7L2 variants are associated with increased proinsulin/insulin ratios but not obesity traits in the Framingham Heart Study

Aims/hypothesis  Common variants in the TCF7L2 gene are associated with type 2 diabetes via impaired insulin secretion. One hypothesis is that variation in TCF7L2 impairs insulin processing in the beta cell. In contrast, the association of related TCF7L2 polymorphisms with obesity is controversial in that it has only been shown in cohorts susceptible to ascertainment bias. We reproduced the association of diabetes-associated variants with proinsulin/insulin ratios, and also examined the association of a TCF7L2 haplotype with obesity in the Framingham Heart Study (FHS). Methods  We genotyped the TCF7L2 single nucleotide polymorphisms rs7903146 and rs12255372 (previously associated with type 2 diabetes) and rs10885406 and rs7924080 (which tag haplotype A [HapA], a haplotype reported to be associated with obesity) in 2,512 FHS participants. We used age- and sex-adjusted linear mixed-effects models to test for association with glycaemic traits, proinsulin/insulin ratios and obesity measures. Results  As expected, the T risk allele of rs7903146 was associated with higher fasting plasma glucose (p = 0.01). T/T homozygotes had a 23.5% increase in the proinsulin/insulin ratio (p = 1 × 10⁻⁷) compared with C/C homozygotes. There was no association of HapA with BMI (p = 0.98), waist circumference (p = 0.89), subcutaneous adipose tissue (p = 0.32) or visceral adipose tissue (p = 0.92). Conclusions/interpretation  We confirmed that the risk allele of rs7903146 is associated with hyperglycaemia and a higher proinsulin/insulin ratio. We did not detect any association of the TCF7L2 HapA with adiposity measures, suggesting that this may have been a spurious association from ascertainment bias, possibly induced by the evaluation of obesity in separate groups of glycaemic cases and controls. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorised users.     

Genetic variants at CDC123/CAMK1D and SPRY2 are associated with susceptibility to type 2 diabetes in the Japanese population

Aims/hypothesis

Recently, rs10906115 in CDC123/CAMK1D, rs1359790 near SPRY2, rs1436955 in C2CD4A/C2CD4B and rs10751301 in ODZ4 were identified as genetic risk variants for type 2 diabetes by a genome-wide association study in a Chinese population. The aim of the present study was to ascertain the role of these four variants in conferring susceptibility to type 2 diabetes in the Japanese population.

Methods

We genotyped 11,530 Japanese individuals (8,552 type 2 diabetes cases, 2,978 controls) for the above single nucleotide polymorphisms (SNPs) and used logistic regression analysis to determine whether they were associated with type 2 diabetes.

Results

In accordance with the findings in a Chinese population, rs10906115 A, rs1359790 C and rs1436955 G were found to be risk alleles. Both rs10906115 and rs1359790 were significantly associated with susceptibility to type 2 diabetes in our study (rs10906115 OR 1.15, 95% CI 1.08, 1.22; p?=?6.10?×?10^?6; rs1359790 OR 1.14, 95% CI 1.06, 1.21; p?=?2.24?×?10^?4). Adjustment for age, sex and BMI had no significant effects on the association between these variants and the disease. We did not observe any significant associations between the SNPs and any metabolic traits, e.g. BMI, fasting plasma glucose (determined for 1,332 controls), HOMA of beta cell function (900 controls) and HOMA of insulin resistance (900 controls; p?>?0.05).

Conclusions/interpretation

The SNPs rs10906115 A and rs1359790 C are significantly associated with susceptibility to type 2 diabetes in the Japanese population, confirming that these alleles are common susceptibility variants for type 2 diabetes in East Asian populations.     

Common variants within 6p21.31 locus are associated with chronic lymphocytic leukaemia and,potentially, other non‐Hodgkin lymphoma subtypes

A recent meta‐analysis of three genome‐wide association studies of chronic lymphocytic leukaemia (CLL) identified two common variants at the 6p21.31 locus that are associated with CLL risk. To verify and further explore the association of these variants with other non‐Hodgkin lymphoma (NHL) subtypes, we genotyped 1196 CLL cases, 1699 NHL cases, and 2410 controls. We found significant associations between the 6p21.31 variants and CLL risk (rs210134: P = 0·01; rs210142: P = 6·8 × 10^?3). These variants also showed a trend towards association with some of the other NHL subtypes. Our results validate the prior work and support specific genetic pathways for risk among NHL subtypes.     

Polymorphisms in <Emphasis Type="Italic">AHI1</Emphasis> are not associated with type 2 diabetes or related phenotypes in Danes: non-replication of a genome-wide association result

Aims/hypothesis A genome-wide association study recently identified an association between common variants, rs1535435 and rs9494266, in the AHI1 gene and type 2 diabetes. The aim of the present study was to investigate the putative association between these polymorphisms and type 2 diabetes or type 2 diabetes-related metabolic traits in Danish individuals. Methods The previously associated polymorphisms were genotyped in the population-based Inter99 cohort (n = 6162), the Danish ADDITION study (n = 8428), a population-based sample of young healthy participants (n = 377) and in additional type 2 diabetes (n = 2107) and glucose-tolerant participants (n = 483) using Taqman allelic discrimination. The case–control study involved 4,104 type 2 diabetic patients and 5,050 glucose-tolerant control participants. Type 2 diabetes-related traits were investigated in 17,521 individuals. Results rs1535435 and rs9494266 were not associated with type 2 diabetes. Odds ratios (OR) were OR_add 1.0 (95% C.I. 0.9–1.2; p _add = 0.7) and OR_add 1.1 (0.9–1.2; p _add = 0.4), respectively, a finding supported by meta-analyses: OR_add 1.0 (0.9–1.1; p _add = 0.6) and OR_add 1.0 (0.9–1.1; p _add = 0.6), respectively. Neither rs1535435 nor rs9494266 were consistently associated with any of the tested type 2 diabetes-related metabolic traits. Conclusions/interpretation Data from large samples of Danish individuals do not support a role for AHI1 rs1535435 nor rs9494266 as major type 2 diabetes variants. This study highlights the importance of independent and well-powered replication studies of the recent genome-wide association scans before a locus is robustly validated as being associated with type 2 diabetes. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorised users.     

Association of genomic loci from a cardiovascular gene SNP array with fibrinogen levels in European Americans and African-Americans from six cohort studies: the Candidate Gene Association Resource (CARe)

Several common genomic loci, involving various immunity- and metabolism-related genes, have been associated with plasma fibrinogen in European Americans (EAs). The genetic determinants of fibrinogen in African Americans (AAs) are poorly characterized. Using a vascular gene-centric array in 23,634 EA and 6657 AA participants from 6 studies comprising the Candidate Gene Association Resource project, we examined the association of 47,539 common and lower frequency variants with fibrinogen concentration. We identified a rare Pro265Leu variant in FGB (rs6054) associated with lower fibrinogen. Common fibrinogen gene single nucleotide polymorphisms (FGB rs1800787 and FGG rs2066861) significantly associated with fibrinogen in EAs were prevalent in AAs and showed consistent associations. Several fibrinogen locus single nucleotide polymorphism associated with lower fibrinogen were exclusive to AAs; these include a newly reported association with FGA rs10050257. For IL6R, IL1RN, and NLRP3 inflammatory gene loci, associations with fibrinogen were concordant between EAs and AAs, but not at other loci (CPS1, PCCB, and SCL22A5-IRF1). The association of FGG rs2066861 with fibrinogen differed according to assay type used to measure fibrinogen. Further characterization of common and lower-frequency genetic variants that contribute to interpopulation differences in fibrinogen phenotype may help refine our understanding of the contribution of hemostasis and inflammation to atherothrombotic risk.     

The genetic basis of asymptomatic codon 8 frame‐shift (HBB:c25_26delAA) β0‐thalassaemia homozygotes

Two 21‐year old dizygotic twin men of Iraqi descent were homozygous for HBB codon 8, deletion of two nucleotides (–AA) frame‐shift β⁰‐thalassaemia mutation (FSC8; HBB:c25_26delAA). Both were clinically well, had splenomegaly, and were never transfused. They had mild microcytic anaemia (Hb 120‐130 g/l) and 98% of their haemoglobin was fetal haemoglobin (HbF). Both were carriers of Hph α‐thalassaemia mutation. On the three major HbF quantitative trait loci (QTL), the twins were homozygous for G>A HBG2 Xmn1 site at single nucleotide polymorphism (SNP) rs7482144, homozygous for 3‐bp deletion HBS1L‐MYB intergenic polymorphism (HMIP) at rs66650371, and heterozygous for the A>C BCL11A intron 2 polymorphism at rs766432. These findings were compared with those found in 22 other FSC8 homozygote patients: four presented with thalassaemia intermedia phenotype, and 18 were transfusion dependent. The inheritance of homozygosity for HMIP 3‐bp deletion at rs66650371 and heterozygosity for Hph α‐thalassaemia mutation was found in the twins and not found in any of the other 22 patients. Further studies are needed to uncover likely additional genetic variants that could contribute to the exceptionally high HbF levels and mild phenotype in these twins.     

Significance of dietary folate intake,homocysteine levels and MTHFR 677 C>T genotyping in South African patients diagnosed with depression: test development for clinical application

Low folate intake in the presence of the functional MTHFR 677 C > T (rs1801133) polymorphism is an important cause of elevated homocysteine levels previously implicated in major depressive disorder (MDD) and many other chronic diseases. In this study the clinical relevance and inter-relationship of these aspects were evaluated in 86 South African patients diagnosed with MDD and 97 population-matched controls participating in a chronic diseases screening program. A questionnaire-based clinical and nutrition assessment was performed, homocysteine levels determined, and all study participants genotyped for MTHFR 677 C > T (rs1801133) using allele-specific TaqMan technology. The folate score was found to be significantly lower in the patient group compared to controls (p?=?0.003) and correlated with increased body mass index (BMI), particularly in females with MDD (p?=?0.009). BMI was significantly higher in the MDD patients compared with controls after adjustment for age and sex (p?=?0.015), but this association was no longer significant after further adjustment for the level of folate intake in the diet. In MDD patients but not controls, the minor T-allele of MTHFR 677 C > T was associated with increased BMI (p?=?0.032), which in turn correlated significantly with increased homocysteine levels. The significant association between BMI and homocysteine levels was observed in both the MDD patient (p?=?0.049) and control (p?=?0.018) study groups. The significantly higher homocysteine levels observed in MDD patients compared to controls after adjustment for age and sex (p?=?0.030), therefore appears to be mediated by the effects of MTHFR 677 C > T and low folate intake on BMI. Detection of the low-penetrance MTHFR 677 C > T mutation reinforces the importance of folate intake above the recommended daily dose to prevent or restore dysfunction of the methylation pathway.     

Association of serine racemase gene variants with type 2 diabetes in the Chinese Han population

A genome‐wide association study in the Chinese Han population has identified several novel genetic variants of the serine racemase (SRR) gene in type 2 diabetes. Our purpose was to systematically evaluate the contribution of SRR variants in the Chinese Han population. rs391300 and rs4523957 in SRR were genotyped respectively in the two independent populations. A meta‐analysis was used to estimate the effects of SRR in 21,305 Chinese Han individuals. Associations between single‐nucleotide polymorphisms and diabetes‐related phenotypes were analyzed among 2,615 newly diagnosed type 2 diabetes patients and 5,029 controls. Neither rs391300 nor rs4523957 were associated with type 2 diabetes in populations. Furthermore, meta‐analysis did not confirm an association between type 2 diabetes and SRR. In the controls, rs391300‐A and rs4523957‐G were associated with higher 30‐min plasma glucose in an oral glucose tolerance test. The present study did not confirm that SRR was associated with type 2 diabetes.     

CARD15 and IL23R influences Crohn's disease susceptibility but not disease phenotype in a Brazilian population

BACKGROUND: Although many genetic variants are identified in association with Crohn's disease (CD), CARD15, IL23R, and ATG16L1 association with CD have been firmly confirmed in Caucasians of European ancestry. The prevalence of CD is rapidly rising in Brazil, where European ancestry is firmly admixed with natives and Africans, resulting in a heterogeneous population. We investigated the contribution of CARD15, IL23R, and ATG16L1 with CD risk in a heterogeneous Brazilian population. METHODS: Genotyping for CARD15 (R702W, G908R, 3020insC), IL23R (rs1004819, rs7517847, rs11209026, rs10889677, rs1495965), and ATG16L1 (rs2241880) was performed in 187 children and adults with CD and 255 healthy ethnically matched controls. Clinical records were systematically reviewed and detailed phenotypic information was obtained. RESULTS: At least 1 CARD15 risk allele was present in 30% of the CD patients compared with 10% of controls. Variants of CARD15 (3020insC and R702W) and IL23R (rs1004819, rs11209026, and rs1088967) were associated with CD. However, no genotype-phenotype correlations were found among the Brazilian CD population with CARD15 or IL23R variants. No significant association was achieved with ATG16L1. CONCLUSIONS: CARD15 and IL23R confer susceptibility to CD in the Brazilian population. However, the presence of these variants did not influence disease phenotype. Further research should be focused on larger sample sizes with population admixture analysis to better understand the risks and genotype-phenotype correlation in populations like Brazil where the prevalence of CD is rapidly rising.     

Relationship between Genetic Variants in Myocardial Sodium and Potassium Channel Genes and QT Interval Duration in Diabetics: The Diabetes Heart Study

Background: Genetic variants in myocardial sodium and potassium channel genes are associated with prolonged QT interval and increased risk of sudden death. It is unclear whether these genetic variants remain relevant in subjects with underlying conditions such as diabetes that are associated with prolonged QT interval. Methods: We tested single nucleotide polymorphisms (SNPs) in five candidate genes for association with QT interval in a family‐based study of subjects with type 2 diabetes mellitus (T2DM). Thirty‐six previously reported SNPs were genotyped in KCNQ1, HERG, SCN5A, KCNE1, and KCNE2 in 901 European Americans from 366 families. The heart rate‐corrected (QTc) durations were determined using the Marquette 12SL program. Associations between the QTc interval and the genotypes were evaluated using SOLAR adjusting for age, gender, T2DM status, and body mass index. Results: Within KCNQ1 there was weak evidence for association between the minor allele of IVS12 +14T>C and increased QTc (P = 0.02). The minor allele of rs2236609 in KCNE1 trended toward significance with longer QTc (P = 0.06), while the minor allele of rs1805123 in HERG trended toward significance with shorter QTc (P = 0.07). However, no statistically significant associations were observed between the remaining SNPs and QTc variation. Conclusions: We found weak evidence of association between three previously reported SNPs and QTc interval duration. While it appears as though genetic variants in previously identified candidate genes may be associated with QT duration in subjects with diabetes, the clinical implications of these associations in diabetic subjects at high risk for sudden death remain to be determined.