Association of MHC class I chain related gene-A microsatellite polymorphism with the susceptibility to T1DM and LADA in Czech adult patients

The results in this study suggest that microsatellite polymorphism within the transmembrane region of MIC-A gene is associated with genetic susceptibility to adult-onset of type 1 diabetes mellitus (T1DM), MIC-A5.1 allele, corrected P = 0.001, whereas it is not associated with latent autoimmune diabetes in adults (LADA) in Czech population. According to our findings, we can hypothesize that adult-onset T1DM and LADA may have partly different immunogenetic aetiopathogenesis.     

Major histocompatibility complex class I chain related gene-A microsatellite polymorphism shows secondary association with type 1 diabetes and celiac disease in North Indians

Microsatellite polymorphism in exon 5 of major histocompatibility complex class I chain related gene-A (MIC-A) has been implicated in the etiology of autoimmune diseases including type 1 diabetes (T1D) and celiac disease (CD). In this study on North Indian population, the MIC-A5.1 allele, carrying a premature termination codon in transmembrane region, was observed with increased frequency in T1D (29.6%, odds ratio OR?=?2.1, P?=?0.00017) and CD patients (40.3%, OR?=?3.37, P?=?1.67E-05) than in controls (16.7%). When the MIC-A5.1 association was adjusted for linkage with human leukocyte antigen (HLA)-DR3, the statistical significance of the association was abolished. This implies that the observed association of MIC-A5.1 is due to its linkage disequilibrium (D'?=?0.94) with HLA-B8-DR3-DQ2 haplotype and is secondary to the overall association with DR3 positive MHC haplotypes.     

MHC class I chain-related gene A transmembrane polymorphism modulates the extension of ulcerative colitis

Recent evidence from several studies has suggested a genetic predisposition in the pathogenesis of ulcerative colitis (UC), which is especially related with major histocompatibility complex (MHC) genes. The aim of this study was to investigate the possible association of human leukocyte antigen (HLA-B, HLA-DR) and MHC class I chain-related-transmembrane (MICA-TM) polymorphism with the behavior and extension of UC. We selected 121 unrelated patients with UC. These were divided into two groups according to the extension of the disease: 31 patients with distal UC and 90 with wide extension UC; 116 blood donors were also selected as healthy controls, all of whom were typed for HLA-B, HLA-DR, and MICA-TM alleles. HLA-B7 was found to be overrepresented in distal UC patients compared with those with extensive UC (p(c) = 0.007, OR = 5.33) and healthy controls (p(c) = 0.03, OR = 4.09). The MICA-A5.1 allele was also increased in distal UC (p(c) = 0.015, OR = 3.82) when compared with extensive forms. These alleles are in strong linkage disequilibrium in our population. The MICA-A5 allele was significantly increased in extensive forms when compared with healthy controls(p(c) = 0.02, OR = 2.4). According to our results, MICA-A5.1 allele seems to be protective against extensive forms of UC, and MICA-A5 may condition a worse progression of the disease. These results are in agreement with other studies that suggest a similar role of such alleles in other diseases, such as insulin-dependent diabetes mellitus and celiac disease.     

MHC class I chain-related gene A transmembrane polymorphism in Spanish women with breast cancer

The NKG2D–major histocompatibility complex class I-related chain A (MICA) system plays a key role in the antitumoral immune response. We studied five alleles of a microsatellite in the MICA transmembrane region; one of which ( MICA-A5.1 ) gives rise to a truncated protein. The MICA-A5 allele was reduced in breast cancer patients compared with healthy controls ( P  = 0.04). Given the association between the HLA-B7 allele and the susceptibility to breast cancer in our area, we also analyzed the distribution of the frequency of the MICA alleles in human leukocyte antigen (HLA)-B7 patients compared with patients with the other alleles. The MICA-A5.1 allele was increased in HLA-B7 patients ( P  = 0.0003). These results suggest that the MICA-A5 allele appears to confer protection against human breast cancer and that the MICA-A5.1 appears to increase the susceptibility to breast cancer in HLA-B7 patients in our area.     

Association of a polymorphism in the betacellulin gene with type 1 diabetes mellitus in two populations

Betacellulin, a member of the epidermal growth factor family, is expressed in fetal and adult pancreas. In vitro and in vivo studies suggest a role for betacellulin in islet neogenesis and regeneration. Therefore, a mutation in the betacellulin gene might lead to fewer beta cells. With reduced beta cell reserve, beta cells may not be able to compensate for an autoimmune attack, and in turn, susceptibility to type 1 diabetes mellitus (T1DM) would increase. Previous mutational analysis identified seven polymorphisms in the betacellulin gene [5′ UT (−233G>C, −226A>G), exon 1 (TGC19GGC, Cys7Gly), exon 2 (CTC130TTC, Leu44Phe), exon 4 (TTG370ATG, Leu124Met), intron 2 (-31T>C), and intron 4 (-4C>T)]. An association study of these variants with T1DM was first carried out in 100 Caucasian subjects with T1DM and 282 Caucasian subjects without diabetes recruited at the University of Maryland. The frequency of the intron 4 T-4 allele was significantly higher among nondiabetic controls than that among diabetic cases (0.29 vs 0.21, p=0.04). Allele frequencies for the other polymorphisms did not differ significantly between cases and controls. The intron 4 T-4 association was then replicated by transmission disequilibrium testing in a separate population of Caucasian parent/offspring with T1DM trios (n=168 trios, 113 informative) recruited at the Medical College of Wisconsin (p=0.024). An interaction of the intron 4 T-4 allele and human leukocyte antigen (HLA) was also detected with undertransmission of the T allele in those T1DM subjects with susceptible HLA types as compared to those T1DM subjects without susceptible HLA types (p=0.018). RNA studies of the intron T-4 variant showed similar RNA levels for intron 4 T-4 and intron 4 C-4 alleles. Additionally, there was no evidence for an effect of this variant on exon–intron splicing. We conclude that the intron 4 T-4 allele in the betacellulin gene is associated with lower risk of T1DM and may interact with HLA. Further studies will be necessary to establish the significance of this association.     

Age-related association of MHC class I chain-related gene A (MICA) with type 1 (insulin-dependent) diabetes mellitus

To assess the contribution of the HLA class I region to susceptibility to and heterogeneity of type 1 diabetes, we investigated the association of polymorphism of MHC class I chain-related gene A (MICA) with age-at-onset as well as susceptibility to type 1 diabetes. One hundred one Japanese patients and 110 healthy control subjects were studied. The frequency of A4 allele was significantly higher and that of A6 allele was significantly lower in patients than in control subjects. The frequency of A5.1 allele was highest in early-onset patients (23.0%), intermediate in intermediate-onset patients (9.2%) and lowest in late-onset patients (7.7%) (trend chi-squared test, p = 0.0098). A5. 1 allele was strongly associated with HLA-B7 and Cw7, suggesting that MICA*A5.1-B7-Cw7 haplotype contains a gene responsible for age-at-onset. A4 allele was associated with a susceptible haplotype, DR4-DQB1*0401, and A6 allele was associated with a protective haplotype, DR2-DQB1*0601, suggesting that the association of MICA with type 1 diabetes susceptibility may be due to linkage disequilibrium with class II haplotypes. These data suggest that MICA gene is associated with age-at-onset and that a gene (or genes) responsible for age-at-onset of type 1 diabetes is located in the HLA class I region, probably near the region of MICA-B-C.     

2型糖尿病胰岛素抵抗和胆固醇酯转运蛋白基因多态性的关联研究

目的 探讨胆固醇酯转运蛋白(cholesteyl ester transfer protein，CETP)基因多态性与2型糖尿病胰岛素抵抗的关系。方法 采用聚合酶链反应和酶切电泳方法对108例2型糖尿病患者进行CETP-TaqIB基因型分型，同时测定血脂、空腹胰岛素、胰岛素敏感指数和胰岛素抵抗指数。结果 正常对照组与2型糖尿病组等位基因频率和基因型分布无统计学意义；2型糖尿病甘油三酯(triglyceride，TG)、总胆固醇(total cholesterol，TC)、低密度脂蛋白胆固醇(low density lipoprotein cholesterol，LDL-C)和载脂蛋白B(apolipoprotein B，apoB)浓度各基因型间差异无统计学意义，而高密度脂蛋白胆固醇(high density lipoprotein cholesterol，HDL-C)、载脂蛋白A1(apolipoprotein A1，apoA1)、空腹胰岛素(fasting insulin，FINS)、胰岛素敏感性指数(insulin sensitivity index，ISI)和HOMA模型胰岛素抵抗指数(homeostasis model assessment-insulin resistance，HOMA-IR)各基因型间差异有统计学意义，HDL-C、apoA，和ISI B2B2型显著高于B1B1型，FINS和HOMA-IR B2B2型显著低于B1B1型；以胰岛素敏感性指数和HOMA-模型胰岛素抵抗指数为因变量进行多元回归分析，ISI和HOMA-IR与体重指数、收缩压、TC、HDL及基因型分型密切相关。结论 CETP-Taq IB基因多态性与2型糖尿病脂代谢及胰岛素抵抗密切关联，可能是胰岛素抵抗的重要遗传因素。     

Productive association between MHC class I and tapasin requires the tapasin transmembrane/cytosolic region and the tapasin C-terminal Ig-like domain

The current model of antigen assembly with major histocompatibility complex (MHC) class I molecules posits that interactions between the tapasin N-terminal immunoglobulin (Ig)-like domain and the MHC class I peptide-binding groove permit tapasin to regulate antigen selection. Much less is known regarding interactions that might involve the tapasin C-terminal Ig-like domain. Additionally, the tapasin transmembrane/cytoplasmic region enables tapasin to bridge the MHC class I molecule to the transporter associated with antigen processing (TAP). In this investigation, we made use of two tapasin mutants to determine the relative contribution of the tapasin C-terminal Ig-like domain and the tapasin transmembrane/cytoplasmic region to the assembly of MHC class I molecules. Deletion of a loop within the tapasin C-terminal Ig-like domain (Δ334-342) prevented tapasin association with the MHC class I molecule K(d). Although tapasin Δ334-342 did not increase the efficiency of K(d) folding, K(d) surface expression was enhanced on cells expressing this mutant relative to tapasin-deficient cells. In contrast to tapasin Δ334-342, a soluble tapasin mutant lacking the transmembrane/cytoplasmic region retained the ability to bind to K(d) molecules, but did not facilitate K(d) surface expression. Furthermore, when soluble tapasin and tapasin Δ334-342 were co-expressed, soluble tapasin had a dominant negative effect on the folding and surface expression of not only K(d), but also D(b) and K(b). In addition, our molecular modeling of the MHC class I-tapasin interface revealed novel potential interactions involving tapasin residues 334-342. Together, these findings demonstrate that the tapasin C-terminal and transmembrane/cytoplasmic regions are critical to tapasin's capacity to associate effectively with the MHC class I molecule.     

Ghrelin基因多态性与2型糖尿病的相关性

目的探讨ghrelin基因多态性与2型糖尿病之间的关系。方法进行ghrelin基因C408A和G346A的多态性分析,同时进行生化指标和临床参数的检测。结果正常对照组(NGT组)C408A基因型CC、CA、AA的基因型频率分别为75.4%、24.0%及0.6%。2型糖尿病组(DM组)中CC、CA及AA的基因型频率分别为70.8%、28.2%及1.0%。NGT组CC基因型者总胆固醇水平明显高于CA AA基因型者(P<0.05);DM组CC基因型者血尿酸水平明显高于CA AA基因型者(P<0.05)。在所有的受试者中未发现G346A多态性存在。结论Ghrelin基因C408A分布与等位基因频率没有明显的差异;本组人群中未发现ghrelinG346A多态性存在;C408A多态性与总胆固醇和尿酸水平相关。     

HLA-DRB基因启动子区多态性与肺结核合并2型糖尿病的相关性

目的研究HLADRB基因启动子区序列与肺结核合并2型糖尿病的相关性。方法用PCRSSP法进行HLADRB基因分型,启动子区扩增产物直接测序。结果病例组DRB109等位基因的频率显著高于对照组(P<0.05)。病例组中DRB基因启动子区-65位碱基T和-8位AG杂合子的频率明显增加(P<0.05)。病例组中DRB109阳性标本-65位碱基T的频率明显增加,G明显减少(P<0.01);+39位碱基C明显增加,T明显减少(P<0.01)。结论DRB109等位基因及HLADRB启动子区多态性与肺结核合并2型糖尿病密切相关。     

No association between the -1031 polymorphism in the TNF-alpha promoter region and type 1 diabetes

Tumor necrosis factor alpha (TNF-alpha) is an important immunomodulator and is believed to be involved in the development or progression of type 1 diabetes. In the following study, we evaluated TNF-alpha promoter polymorphisms at positions -863 and -1031 and their association with type 1 diabetes in a group of 210 diabetic patients from Lebanon. Our results show that in our population, the C allele is predominant at position -863, whereas the A allele is very rare (2%). At position -1031, however, the C and T allele distribution was similar in both the patient (17.8% vs 82.2%, respectively) and the control (21.4% vs 79.6%) groups. No association of TNF-alpha genotype at position 1031 with type 1 diabetes was found as demonstrated by the family-based association test and the transmission disequilibrium test. However, when patient genotypes were compared, the recessive CC genotype was only found in type 1 diabetic males but not in type 1 diabetic females. This observation, however, requires further investigation in a larger sample before conclusive association to gender is suggested. In conclusion, our results demonstrate that no association between TNF-alpha polymorphism and type 1 diabetes seems to exist in our population.     

ELOVL6基因单核苷酸多态性与妊娠期糖尿病的相关性

目的探讨辽宁地区汉族人群中超长链脂肪酸延伸酶6(elongation of very long chain fatty acids protein 6,ELOVL6)基因2个SNP位点与妊娠期糖尿病(gestational diabetes mellitus,GDM)的相关性。方法选择2012年6月至2013年6月来我院就诊GDM孕妇128例(GDM组),同期健康孕妇145例作为对照组。记录一般临床资料包括年龄、孕周、身高、体质指数(body mass index,BMI),空腹胰岛素(FIN)及空腹血糖(FPG)水平。采用PCR结合直接测序,检测ELOVL6基因rs12504538和rs17041272位点SNP基因型频率和等位基因频率。分析两组孕妇不同基因型及等位基因胰岛素抵抗指数(HOMA-IR)和胰岛β细胞功能指数(HOMA-β)的差异。结果 GDM组FPG、FIN及HOMA-IR值高于健康对照组,但HOMA-β水平低于健康对照组(0.05)。SNP位点rs17041272基因型及等位基因频率在GDM组和对照组间无差异。rs12504538位点基因型(TT,CT,CC)与对照组比较,T等位基因频率明显高于对照组。GDM组CT基因型孕妇FPG、FIN及HOMA-IR水平高于TT基因型者(0.05)。结论 ELOVL6基因SNP位点rs12504538与GDM发病相关,可能是GDM潜在靶向位点,C等位基因为易感基因。     

云南彝族2型糖尿病与HLA-DQA1等位基因多态性的关联研究

目的探讨云南彝族2型糖尿病与HLA—DQA1等位基因多态性的关联性。方法采用聚合酶链反应-序列特异性引物技术，对58例云南楚雄地区彝族2型糖尿病患者和同地区82名彝族正常对照者进行基因分型，做2型糖尿病与HLA—DQA1等位基因多态性的关联分析。结果云南彝族2型糖尿病组与彝族对照组比较，HLA-DQA1＊0301等位基因频率明显高于对照组（P=0．002，RR=3．097）；HLA—DQA1＊0601等位基因频率明显低于对照组（P=0．025，RR=0．429），差异有统计学意义。结论HLA—DQA1＊0301是云南彝族2型糖尿病的易感基因；HLA—OQAI＊0601是云南彝族2型糖尿病的保护基因。     

Association between type 1 diabetes and polymorphism of the CTLA-4 gene in a Tunisian population]

Susceptibility to type 1 diabetes mellitus is strongly associated with particular HLA class II alleles. However, non HLA genetic factors are likely to be required for the development of disease. The candidate genes include the cytotoxic T lymphocyte associated 4 (CTLA-4) located on chromosome 2q33 and designated (IDDM12), which encodes a cell surface negative signal T molecule providing for activation. We investigated CTLA-4 exon 1 dimorphism in 74 type 1 patients and a control group of 48 healthy subjects from Tunisia using two methods PCR (polymerase chain reaction) allele specific and polymerase chain reaction restriction fragment length polymorphism (PCR RFLP). The CTLA-4/G allele was found on 68.9% in type 1 patients as compared to 51.02% in controls (p = 0.002), mostly in homozygous from 43.24% versus 22.45% (p = 0.0058). This results indicate that CTLA-4/G allele was significantly associated with predisposition to type 1 diabetes in our group from Tunisian population.     

NAT2基因多态性与2型糖尿病的关系

目的探讨NAT2基因多态性与2型糖尿病易感性的关系,为糖尿病的有效防治提供科学依据。方法采用PCR及测序技术对174例2型糖尿病患者和174例健康者的NAT2基因4个常见突变位点进行检测。结果糖尿病组中NAT2等位基因频率分别为：Wt（69.54%）,M2（16.37%）,M3（10.63%）,M1（3.44%）。与正常对照组比较差异无显著性。NAT2基因型（WT/WT,WT/Mx,Mx/Mx）在糖尿病组中分布频率分别为44.82%,49.42%,5.74%,两组间比较差异显著。糖尿病组中快乙酰化者164例（占94.25%）,慢乙酰化者10例（占5.75%）,两组间比较有差异。携带NAT2快乙酰化基因型者患2型糖尿病的风险是携带NAT2慢乙酰化基因型者的3.98倍。结论本研究提示快乙酰化代谢表型可能是糖尿病的一个遗传易感因素,而慢乙酰化代谢表型可能对糖尿病的发生具有一定保护作用。     

Leptin基因甲基化与糖尿病的相关性研究

目的 探讨瘦素基因启动子区甲基化及蛋白表达与糖调节受损(impaired glucose regulation,IGR)以及2型糖尿病(type 2 diabetes mellitus,T2DM)的相关性.方法 采用甲基化特异性PCR对不同血糖水平的个体进行Leptin基因启动子区甲基化检测.用双抗体夹心ABC-酶联免疫吸附法检测血液标本中的瘦素蛋白表达量.结果 与正常对照组(59.2％)相比,T2DM和IGR组Leptin基因的甲基化率偏低(分别为31.5％和43.6％),差异具有统计学意义(x2分别为22.499,5.109,P值均＜0.05).T2DM与IGR组相比甲基化率偏低(x2=3.962,P＜0.05),差异具有统计学意义.患者的瘦素含量相对于正常人均偏高,但仅T2DM组与正常人差异具有统计学意义(q=6.81,P＜0.01).直线回归分析提示,瘦素含量随DNA甲基化程度的降低有增高的趋势,两者呈显著负相关(r=-0.95,P＜0.01).结论 Leptin基因启动子区甲基化与瘦素代谢紊乱可能参与糖尿病的发生和发展.检测IGR和T2DM患者Leptin基因启动子区的甲基化状态和基因蛋白表达,对于早期干预、延缓病程具有一定的参考价值.     

Association between type 1 diabetes age-at-onset and intercellular adhesion molecule-1 (ICAM-1) gene polymorphism

We investigated the intercellular adhesion molecule-1 (ICAM-1) gene polymorphism in 90 patients with young-onset type 1 diabetes, 74 with adult-onset type 1 diabetes, and 171 control subjects. The distribution of C-T genotypes and allele frequencies in exon 6 of the ICAM-1 gene was significantly different between adult-onset type 1 diabetes patients and controls (chi(2) = 9.76, p = 0.0076), and between patients with adult-onset and young-onset type 1 diabetes (chi(2) = 11.28, p = 0.0036). In contrast, we failed to detect any association between patients with young-onset type 1 diabetes and controls. Our data suggest that ICAM-1 exon 6 gene polymorphism affects the age-at-onset of type 1 diabetes and that different pathogenetic mechanisms may exist between young-onset and adult-onset type 1 diabetes.