临床患者检测卡马西平药物基因位点在预防Steven-Johnson综合征和中毒性表皮坏死松解症中的应用

目的 检测卡马西平药物的耐药位点,为使用卡马西平药物治疗的患者提供精准的用药指导,避免Steven-Johnson综合征和中毒性表皮坏死松解症的出现。方法 收集148例血液样本,使用荧光探针原位杂交技术对卡马西平药物的耐药位点HLA-B*1502TA(C >G)和HLA-B*1502TB(C>T)进行检测和结果分析,评估不同患者卡马西平药物使用的可行性。结果 148例患者中,HLA-B*1502 TA(C >G)位点检测结果为CC(野生型)的患者126例(85.14%),检测结果为CG(杂合突变型)的患者21例(14.19%),检测结果为GG(纯合突变型)的患者1例(0.67%); HLA-B*1502TB(C > T)位点检测结果为CC(野生型)的患者109例(73.65%),检测结果为CT(杂合突变型)的患者37例(25.00%),检测结果为TT(纯合突变型)的患者2例(1.35%)。39.19%(58/148)的患者使用卡马西平有出现Steven-Johnson综合征和中毒性表皮坏死松解症的风险。结论 在使用卡马西平治疗前给患者作卡马西平化学药物基因检测,根据检测结果合理精准用药,可使39.19%患者避免出现Steven-Johnson综合征和中毒性表皮坏死松解症的风险,为患者提供安全用药指导。     

中国南方汉族人群中卡马西平导致SJS/TEN与HLA-B基因的相关性

目的:探讨中国南方汉族人群中卡马西平(CBZ)所致Stevens-Johnson综合征/中毒性表皮坏死松解症(SJS/TEN)与HLA-B基因的相关性。方法:采用病例对照研究,收集11例CBZ-SJS/TEN患者(CBZ-SJS/TEN组)、93例CBZ耐受患者(CBZ耐受组)及93例未服用抗癫痫药物的正常人(正常对照组)。PCR和测序法检测其HLA-B*1502基因型;χ2检验分析HLA-B*1502及其他HLA-B位点与CBZ-SJS/TEN的相关性。结果:CBZ-SJS/TEN组的HLA-B*1502基因阳性率为72.7%,显著高于CBZ耐受组及正常对照组。3例HLA-B*1502阴性CBZ-SJS/TEN患者的基因型分别为HLA-B*1511/1511、5401/5401及4001/4601。除HLA-B*1502之外,HLA-B*1511基因频率在CBZ-SJS/TEN患者与中国南方汉族正常人群之间具有显著的统计学差异,其他位点差异均无显著性。结论:在我国南方汉族人群中HLA-B*1502与CBZ-SJS/TEN具有相关性,建议汉族人群在服用CBZ前应该进行基因型检测。同时,对HLA-B*1502阴性个体使用CBZ治疗时,需密切监视,避免SJS/TEN的出现。     

HLA‐B*1502 Strongly Predicts Carbamazepine‐Induced Stevens–Johnson Syndrome and Toxic Epidermal Necrolysis in Thai Patients with Neuropathic Pain

Background: Carbamazepine (CBZ) is one of the standard pharmacological treatments for neuropathic pain. However, its serious adverse drug reactions include Stevens–Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN). Recently, HLA‐B*1502 allele was implicated as a genetic marker of CBZ‐induced SJS/TEN in some Asian epilepsy populations. Methods: This is a case control study to describe the clinical characteristics of SJS/TEN in Thai patients with neuropathic pain who were treated with CBZ, and to determine the association of HLA‐B*1502 in these patients, comparing with those who exposed to CBZ for at least 6 months without any cutaneous reactions. Results: Thirty‐four SJS/TEN patients and 40 control patients were included in this study. Mean age of SJS/TEN patients was 47 years. SJS/TEN was developed in 10.8 ± 1.4 days after initiation of CBZ. HLA‐B*1502 allele was found in 32 of 34 SJS/TEN patients (94.1%) but it was found only in 7 of 40 control patients (17.5%). The association was very strong with an odds ratio of 75.4. Sensitivity and specificity of this HLA‐B*1502 genotype test were 94.1% and 82.5%, respectively, while the positive predictive value and negative predictive value were 1.43% and 99.98%, respectively. Positive and negative likelihood ratios were 5.37 and 0.07, respectively. Conclusions: HLA‐B*1502 is a strong genetic marker for CBZ‐induced SJS/TEN in Thai patients with neuropathic pain. The screening for this marker should be performed prior to initiation of CBZ treatment to assess the risk of this serious side effect.     

四川骨髓库汉族人群HLA-B~* 15等位基因分布

目的采用聚合酶链反应-序列分析基础上的HLA分型(polymerase chain reaction-sequence based typ-ing,PCR-SBT)方法,研究中国造血干细胞捐献者资料库(以下简称为中华骨髓库,CMDP)四川分库中四川籍汉族人群HLA-B*15组等位基因的分布特点。方法从四川骨髓分库中汉族人群中/低分辨分型HLA-B*15阳性样本中按不同血清学特异性分层抽取107例样本,应用PCR-SBT技术进行测序分型,获得四川籍汉族人群B*15组高分辨分型结果。应用方根法计算HLA-B*15各等位基因频率,同时与其他人群资料进行比较。结果共检测到16种已知HLA-B*15等位基因和1例未知等位基因。本研究中检出的16种等位基因有:B*15010101(B62),B*1502(B75),B*1503(B72),B*1505(B62),B*1507(B62),B*151101(B75),B*1512(B76),B*1513(B77),B*1517(B63),B*1518(B71),B*1525(B62),B*1527(B62),B*1529(B15),B*1532(B62),B*1546(B72),B*1558(B62)。其中以B*1502(36.2%)最常见,其次为B*15010101(21.6%),B*151101(9.5%),B*1518(6.9%),B*1525(6.0%),这5种等位基因占B*15等位基因家族的80%。在B*15等位基因家族中,表达B75抗原的等位基因B*1502和B*151101共占45.7%,但表达B62抗原的B*15等位基因多态性最强,共检出7种等位基因。此外,本研究发现1例未知等位基因,该等基因序列与目前所有已知的B*15或B*46等位基因序列均不相同,在外显子3的116位处存在1个点突变C->T。结论研究表明在四川籍汉族人群中HLA-B*15等位基因水平表现出丰富的多态性和特有的分布特征。     

Clinical pharmacogenetics implementation consortium guidelines for HLA-B genotype and abacavir dosing

Human leukocyte antigen B (HLA-B) is responsible for presenting peptides to immune cells and plays a critical role in normal immune recognition of pathogens. A variant allele, HLA-B*57:01, is associated with increased risk of a hypersensitivity reaction to the anti-HIV drug abacavir. In the absence of genetic prescreening, hypersensitivity affects ~6% of patients and can be life-threatening with repeated dosing. We provide recommendations (updated periodically at http://www.pharmkgb.org) for the use of abacavir based on HLA-B genotype.     

HLA-B*5701 screening for susceptibility to abacavir hypersensitivity

The introduction of highly active antiretroviral therapy (also known as combination therapy) has transformed the nature of HIV infection from a severe and ultimately fatal disease to that of a manageable chronic condition. HIV drugs are highly efficacious, but their use comes at the cost of a range of drug-related adverse events, including severe drug hypersensitivity reactions (HSRs) that have been most notably associated with abacavir and nevirapine therapy. This article discusses the issues of pharmacogenetic screening, in the light of the strong genetic association of the HLA-B*5701 allele and the susceptibility to developing abacavir HSRs. It also presents the screening's impact on clinical practice and discusses the practical considerations that influence the introduction and cost-effectiveness of such screening.     

中国北方汉族骨髓供者HLA-B＊15组基因多态性的PCR-SBT分型研究

为了研究中国北方汉族骨髓供者HLA—B＊15等位基因的分布特征，探讨其可能对临床供体选择的影响，从中华骨髓库陕西分库内随机抽取815名已知低分辨分型结果中国北方汉族骨髓供者，采用聚合酶链反应-碱基序列直接测序（PCR—SBT）方法对其中206例HLA—B＊15阳性样本和另外附加17例样本进行HLA—B位点DNA测序分析，并应用同源模建分子模拟技术对所有结果模拟出三维结构，用计算机软件Swiss—PdbViewer比较模拟结构间的差异大小。结果表明：随机抽取的815例样本HIJA—A、B、DRB1基因分布符合Hardy—Weinberg平衡定律，HIJA—B＊15基因频率为0．1379，总共检出16种HIJA—B＊15等位基因，分属7种血清学特异性，以B＊1501、B＊1511、B＊1502和B＊1518为主，频率分别为0．0485、0．0215、0．0178和0．0160，累计频率构成比占全部B＊15的75．11％，其余12种B＊15等位基因频率均〈0．0100。19例HIJA—B＊15，-测序分析表明，其中10例中低分辨水平上的纯合子中仅4例为真正意义上的B＊15xx，-纯合子，且均由各自优势基因构成。三维结构模拟分析发现同一血清型中既存在结构差异微小的等位基因，如B＊1501、1505、1507、1525、1527、1532（RMSD≤0．02nm），也存在差异较大的等位基因，如B＊1502、1511、1521之间以及B＊1503、1546之间（RMSD均为0．29nm），而一些分属不同血清型的等位基因之间结构却近似（RMSD值≤0．02nm）。结论：本研究应用PCR—SBT，首次取得了中国北方汉族样本量最大的高分辨水平HLA—B＊15基因多态性分布特征，这将有助于临床患者寻找合适供者，并为移植免疫及本地区群体遗传学等方面的研究提供了重要依据，且对于临床选择最适供者，像HLA—B＊15这样血清学特异性及基因亚型高度多态性的家族进行准确的高分辨分型是必要的。     

Genetic HLA Associations in Complex Regional Pain Syndrome With and Without Dystonia

We previously showed evidence for a genetic association of the human leukocyte antigen (HLA) system and complex regional pain syndrome (CRPS) with dystonia. Involvement of the HLA system suggests that CRPS has a genetic component with perturbed regulation of inflammation and neuroplasticity as possible disease mechanisms. However, it is at present unclear whether the observed association with HLA-B62 and HLA-DQ8 in CRPS patients with dystonia also holds true for patients without dystonia. Therefore, we tested the possible association with HLA-B62 and HLA-DQ8 in a clinically homogeneous group of 131 CRPS patients without dystonia. In addition, we investigated the possible association with other alleles of the HLA-A, HLA-B, HLA-C, HLA-DR, and HLA-DQ loci. We showed an increased prevalence of HLA-DQ8 (molecularly typed as HLA-DQB1*03:02; OR = 1.65 [95% CI 1.12–2.42], P = .014) in CRPS without dystonia, whereas no association was observed for HLA-B62 (molecularly typed as HLA-B*15:01; OR = 1.22 [95% CI .78–1.92], P = .458). Our data suggest that CRPS with and CRPS without dystonia may be genetically different, but overlapping, disease entities because only HLA-DQ8 is associated with both. The findings also indicate that distinct biological pathways may play a role in both CRPS subtypes.PerspectiveThis study is the first to replicate a specific HLA region conferring genetic risk for the development of CRPS. Moreover, associations of HLA-DQ8 with both CRPS with and CRPS without dystonia, and HLA-B62 only with CRPS with dystonia, suggest that these disease entities may be genetically different, but overlapping.     

少儿强直性脊柱炎与幼儿类风湿性关节炎HLA-B27亚型的鉴别诊断

背景少儿强直性脊柱炎( juvenile ankylosing spondylitis, JAS)和幼儿类风湿关节炎( juvenile rheumatoid arthritis, JRA)与 HLA-B27抗原关联研究已近 25年历史,国外有学者报道强直性脊柱炎( ankylosing spondylitis, AS)和关节炎与 HLA-B27等位基因亚型关联不同. 目的探讨 HLA-B27等位基因亚型与 JAS和 JRA的关联性及其在发病机制中的作用 ,以期能够找到早期诊断 JAS检测方法. 设计非随机对照的实验研究. 地点、对象和方法纳入 60 例北京儿童医院住院及门诊的 JAS和 JRA患者, 5个家系中患者的父亲或母亲 5例及 9例正常个体(来源于 200多例健康自愿骨髓移植供者).用 PCR/SSP方法对 74例 HLA-B27等位基因亚型进行研究 ,并进行关联分析. 主要观察指标 JAS和 JRA与 HLA-B27等位基因亚型相关性分析; HLA-B* 2704等位基因在 JAS和 JRA中的差异 ;家系资料 ;单倍型分析 ;纯合子分析.表明 HLA-B* 2704与 C* 1202连锁紧密而与 HLA-A连锁不紧密, JAS有明显家族遗传倾向. 结果 本组人群的 HLA-B27等位基因由 HLA-B* 2704,* 2705,* 2702,* 2707 4种亚型组成 ,其中 JAS患者 HLA-B27等位基因亚型频率 B* 2704为 56.25% ;B* 2705为 40.63% ;B* 2702为 3.13% ;JRA HLA-B27等位基因亚型频率为 B* 2705为 60.7% ;B* 2704为 28.57%; B* 2702为 3.57% 及 B* 2707为 7.14% ;JAS与 JRA结果比较 , HLA-B* 2704基因频率在 JAS组高于 JRA组 (RR=3.21,P< 0.05). 结论JAS与 HLA-B* 2704等位基因亚型关联.对 HLA-B27等位基因亚型的检测 ,可成为 JAS和 JRA鉴别诊断中一个有价值实验指标.     

HLA-B~*27基因亚型与强直性脊柱炎的相关性研究

目的比较强直性脊柱炎患者与中华骨髓库福建人群中HLA-B*27基因携带者HLA-B*27基因亚型的分布差异;探讨HLA-B*27基因亚型与强直性脊柱炎的相关性。方法中华骨髓库中HLA-B*27基因携带者(阳性对照组)采用PCR-SSO方法检出,强直性脊柱炎患者(AS组)HLA-B*27基因采用低分辨PCR-SSP方法检出;2组HLA-B*27基因亚型均采用高分辨PCR-SSP方法检测。结果阳性对照组130名HLA-B*27基因携带者中,共检出B*2703、B*2704、B*2705、B*2706、B*2707、B*2711、B*27207种基因亚型;在强直性脊柱炎患者中共检出B*2704、B*2705、B*2707、B*2711、B*27155种基因亚型。两组HLA-B*27基因亚型的频率的差异无显著性意义(P>0.05)。结论HLA-B*27基因健康携带者与强直性脊柱炎患者HLA-B*27基因亚型的总体分布未见显著性差异。     

HLA-B无效等位基因B*5408N的核苷酸序列分析

本研究探讨HLA新的等位基因HLA-B＊5408N的分子基础。采用商用抽提试剂盒抽提样本DNA,利用单链特异性引物PCR方法扩增先证者HLA-B基因的第2-4外显子,对PCR扩增产物直接进行第2、3、4外显子双向测序分析。结果表明：先证者样本测序得到两个等位基因,其中一个等位基因为HLA-B＊1527,另一个经blast验证其为新的等位基因,新的等位基因序列已递交GenBank（DQ295998,DQ295999,DQ296000）。与最接近的HLA-B＊5401等位基因序列相比,新的等位基因仅在第3外显子上有1个核苷酸不同,即第553位G→T,这导致第161位氨基酸Glu（GAG）→终止密码（TAG）,蛋白质的翻译提前终止。血清学方法未能检出HLA-B54抗原。结论：该等位基因为HLA-B无效表达等位基因,已被世界卫生组织HLA因子命名委员会正式命名为HLA-B＊5408N。     

Incidence of abacavir hypersensitivity and its relationship with HLA-B*5701 in HIV-infected patients in Taiwan

OBJECTIVES: To describe the incidence of hypersensitivity to abacavir and frequency of human leucocyte antigen (HLA)-B*5701 in HIV-infected Taiwanese persons. METHODS: Medical records of 337 HIV-infected Taiwanese in whom abacavir-containing combination antiretroviral therapy (CART) was prescribed from 1 May 2001 to 31 December 2006 were reviewed, and HLA typing of the patients was performed in 320 patients (232 receiving abacavir and 88 not receiving abacavir) with available blood samples. HLA class I and II polymorphisms were determined by PCR with specific primers. HLA-B*5701 was further confirmed by sequence-based typing. RESULTS: Of the 337 patients, median CD4 count was 166.5 cells/mm3 (range, 1.0-1914.0) and 83 patients (24.6%) had AIDS-defining opportunistic infections. Thirty-eight patients (11.3%) discontinued abacavir within 6 weeks of starting abacavir-containing CART. Among them, 10 patients had successful abacavir re-challenge and another 11 patients had other specific reasons for abacavir discontinuation. Therefore, 14 patients (4.2%) were classified as cases in whom abacavir hypersensitivity could not be excluded, and 3 patients (0.9%) met the criteria of abacavir hypersensitivity. Of the 320 patients undergoing HLA typing, HLA-A02 was the most common allele and only one individual (0.3%) expressed HLA-B*5701. Along with some differences in allele distributions, there was a significant difference in the genetic frequency of HLA-B57 in our patients compared with those of previous studies in other Chinese populations. CONCLUSIONS: Abacavir hypersensitivity was less frequently encountered in HIV-infected Taiwanese initiating abacavir-containing CART than in Caucasians, which might be explained by the low frequency of the HLA-B*5701 allele.     

DNA序列分析鉴定HLA新等位基因B~*0740

目的确认一个中国人群中的新HLA等位基因。方法应用单倍型特异性分离(haplotype-specific ex-traction,HSE)技术和DNA序列分析技术鉴定HLA-B~*的新等位基因。结果被检标本HLA-B位点有一个等位基因的核苷酸序列与任何已知的HLA等位基因均不同,与同源性最高的B~*0705相比,在exon3区域中的605位碱基由A>T,引起编码178位的氨基酸由赖氨酸(K)变成甲硫氨酸(M)。血清学分型表明新等位基因的免疫学表型仍为HLA-B7。家系分析提示,HLA-B~*0740基因来源于其母亲。结论该等位基因序列为HLA-B位点的一个新等位基因,于2005年2月由WHO HLA因子命名委员会正式命名为HLA-B~*0740。     

External quality assessment of HLA-B*5701 reporting: an international multicentre survey

OBJECTIVES: HLA-B*5701 strongly predicts abacavir hypersensitivity (HSR), but implementation of effective routine screening into clinical practice requires testing be practical and accurate. We tested the proficiency of HLA-B*5701 typing among laboratories using sequence-specific primer PCR. DESIGN AND METHODS: DNA panels (1 and 2) were distributed to seven laboratories (A to G) for blinded typing of the HLA-B*5701 allele. Panel 1 (n = 10 samples; n = 7 laboratories) included 3 positives and other closely related B17 subtypes (B*5702, B*5703, B*5704 and B*5801). Panel 2 (n = 96 samples; n = 4 laboratories) included 36 positives among a broad spectrum of other B alleles. Two laboratories (A and B) also submitted 96 routine samples, typed by the same methodology, to the reference centre for additional analysis by sequence-based typing. RESULTS: All laboratories correctly typed panel 1 for HLA-B*5701 carriage. Laboratories A, B and C identified HLA-B*5701 alleles in panel 2 with 100% sensitivity and 100% specificity. Laboratory D reported one false negative, reportedly due to a sampling error. The results obtained for routine samples typed by laboratories A and B and those generated by the reference laboratory using sequencing were fully concordant. CONCLUSIONS: Detection of HLA-B*5701 alleles among laboratories was 100% specific and 99.4% sensitive, indicating that participating HIV testing laboratories were currently offering effective primary screening to identify individuals at high risk of abacavir HSR. Accurate reporting of HLA-B*5701 status is critical for the safe administration of this drug and participation in quality assurance programmes by all sites who report HLA-B*5701 status should be promoted.     

基因组序列分析HLA新等位基因B*3818内含子和外显子同时突变

目的 分析HLA新等位基因B*3818的基因组序列.方法 克隆测序方法 对PCRSBT中发现的1个未知HLA-B等位基因的基因组序列进行双向全长测序,并采用微量淋巴细胞毒方法 鉴定该等位基因编码分子的抗原特异性,通过群体调查和家系分析了解该等位基因的群体分布频率和单倍型组成情况.结果 新等位基因HLA-B*3818(序列注册号为FJ561482)与B*380201在第4外显子和第5内含子同时存在1个核苷酸的差异.第4外显子的第660位碱基由C变为A,导致第196个密码子由GAC变为GAA,相应氨基酸由天门冬氨酸变为谷氨酸,与IMGT/HLA中的HLA-B等位基因的序列进行对比,该突变为新的单核苷酸多态性位点.第5内含子的第2133位碱基由A变为C,除此之外,B*3818的内含子序列与B*380101、B*380201和B*3814相同.该新HLA等位基因的血清学特异性为B38,其在中国汉族人群中的分布频率小于0.000 5,家系调查结果 表明携带该新等位基因的单倍型为A*030101-CW*010201-B*3818-DRB1-1312-DQB1*060101.结论 新等位基因HLA-B*3818的内含子和外显子同时存在变异,研究新等位基因的基因组序列可为HLA基因相关研究和应用提供更多的序列信息.     

广东汉族人群HLA-B~* 15等位基因分布

目的了解广东献血者汉族人群HLA-B*15等位基因的多态性。方法从1 691名广东汉族献血者中采用中/低分辨分型获得带有HLA-B*15基因型466例样本,进一步应用PCR-SBT技术进行测序分型,获得广东汉族人群B*15高分辨分型结果。应用PyPop软件计算HLA-B*15各等位基因频率,同时与其他人群资料进行比较。结果共检测到16种已知HLA-B*15等位基因,其中以B*15∶02(64.75%)最常见,其次为B*15∶01(13.26%),B*15∶25(4.554%),B*15∶27(4.158%),B*15∶12(3.960%),这5种等位基因占B*15等位基因家族的90.69%。在B*15等位基因家族中,表达B75抗原的等位基因B*15∶02、B*15∶11和B*15∶21共占67.92%,但表达B62抗原的B*15等位基因多态性最强,共检出6种等位基因。结论广东汉族人群中HLA-B*15等位基因表现出高度的多态性及其特有的分布特征。     

新的HLA-B*4061等位基因的核苷酸序列分析

本研究探讨HLA新的等位基因HLA-B＊4061的分子基础。采用盐析法抽提样本DNA，利用PCR方法扩增先证者HLA-B基因的第1-8外显子，PCR产物直接经TOPO克隆到质粒载体中得到单链，对所得克隆进行HLA-B基因第2、3、4外显子双向测序分析。应用PCR-SSP方法证实测序所发现的突变。结果表明：先证者样本克隆测序得到2个等位基因，其中1个等位基因为B＋4601，另1个经blast验证其为新的等位基因，新的等位基因序列已递交GenBank（DQ089628，DQ089629，DQ089630）。与最接近的B＊400101等位基因序列相比，新的等位基因仅在第2外显子上有1个核苷酸不同，即第272位C→A，导致第67位氨基酸Ser→Tyr。结论：HLA-B＊4061等位基因为新的HLA-B等位基因，已荣获世界卫生组织HLA因子命名委员会正式命名。     

The frequency of HLA class I and II alleles in Turkish childhood acute leukaemia patients

In this study, blood samples were taken from 200 patients with childhood acute leukaemias, including acute lymphoblastic leukaemia (ALL) and acute myeloid leukaemia (AML), and from 100 healthy volunteers (controls). The frequency of the human leucocyte antigen (HLA)-DRB1*04 allele was significantly higher, and the frequencies of the HLA-A23 and HLA-B7 antigens were significantly lower, in patients with ALL compared with controls. Among patients with AML, the frequency of the HLA-B49 antigen and the HLA-DRB1*15 allele were significantly higher, whereas the frequencies of the HLA-A11 and HLA-B38 antigens were significantly lower compared with controls. The frequency of the HLA-DRB1*04 allele was also significantly higher in male patients with ALL and AML, whereas the HLA-DRB1*13 allele was found significantly less frequently in male AML and female ALL patients than in controls. To date, this is the only study to evaluate the associations between HLA molecules and leukaemia in a Turkish population with acute childhood leukaemia.     

HLA-DPB1 polymorphisms on the MHC-extended haplotypes of families of patients with Graves' disease: two distinct HLA-DR17 haplotypes

Abstract HLA-DPB1 polymorphisms were investigated in 217 members of 21 multiplex families of patients with Graves' disease, who had previously been haplotyped, using in vitro enzymatic DNA amplification and hybridization with sequence-specific oligonucleotide probes. Using the strategy of group-specific amplification, we were able to assign 19 DPB1 alleles with the use of 13 sequence specific oligonucleotide probes. No recombination was found between HLA-DPB1 and the HLA-DR/DQ complex in 243 informative meioses. HLA-DPB1*0401 was found to be the most common allele followed by DPB1*0101, *0201 and 0402 with allele frequencies of 0·4214, 0·1132, 0·1069 and 0·1006, respectively. Besides the strong linkage disequilibrium between HLA-DPB1*0101 allele and the HLA-B8, DR17/DQ2 haplotype; HLA-DPB1*0202 and *1101 alleles were also found to be significantly associated with HLA-B18 and DR7 with P _c < 0·001 and P _c < 0·009, respectively. HLA-DR17/DQ2 was found to be more commonly associated with HLA-DPB1*0101 on the Affected haplotypes (from family members affected with Graves' disease) while associated with DPB1*0401 on the Ab + ve haplotypes (deduced from thyroid autoantibody positive unaffected members). The differences in the frequency of this preferential association on the Affected and Ab + ve haplotypes was statistically significant (χ²= 10·18, df = 2, P < 0·007). Though it is rather unlikely that the HLA-DPB1 polymorphism by itself could contribute a direct role towards the genetic susceptibility for the development of autoimmune thyroid disease, it could serve as a marker in identifying family members with the HLA-DR17/DQ2 haplotype who are more likely to develop Graves' disease or thyroid autoantibodies.     

TPMT genotype and its clinical implication in renal transplant recipients with azathioprine treatment

BACKGROUND: Thiopurine S-methyltransferase (TPMT) catalyses the S-methylation of thiopurine drugs. Patients with intermediate or deficient TPMT activity are at risk of toxicity after receiving standard doses of these drugs. OBJECTIVE: This study determined the frequencies of TPMT alleles (TPMT*2, *3A, *3B and *3C) and explored the association between TPMT genetic polymorphism and the development of adverse drug reactions in Chinese renal transplant patients receiving azathioprine (AZA). METHODS: TPMT genotypes were determined using polymerase chain reaction-based assays in 122 renal transplant patients and 210 healthy subjects. Biochemical and clinical data were retrospectively evaluated after renal transplantation. RESULTS: Of 122 patients, eight (allele frequency 3.28%) were heterozygous for TPMT*3C and no TPMT*2, *3A or *3B or homozygous TPMT*3C subjects were identified. The pattern and frequency of the main mutant TPMT alleles were similar in patients and healthy subjects. Four of five patients (80%) with haematopoietic toxicity were heterozygotes. TPMT heterozygosity was associated with significant reductions in haematological indices and a significant decrease in cyclosporine plasma concentrations in the first year after renal transplantation. No association between TPMT genotype and renal rejection was identified. CONCLUSION: Our results, together with those of others pointing in the same direction, suggest that genotyping the major TPMT variant alleles may be a valuable tool in preventing AZA toxicity and optimization of immunosuppressive therapy.