胰腺癌组织中人磷脂酰乙醇胺结合蛋白4的表达及临床意义

目的:探讨人磷脂酰乙醇胺结合蛋白4(hPEBP-4)在胰腺癌中的表达及临床意义。方法:采用qRT-PCR、Western blot和免疫组化方法检测30例胰腺癌组织及其癌旁组织中hPEBP-4的mRNA与蛋白表达,分析hPEBP-4表达水平与胰腺癌患者临床病理参数和预后的关系。结果:qRT-PCR与Western blot结果显示,相对于癌旁组织,30例胰腺癌组织中hPEBP-4的mRNA与蛋白表达上调者24例(80.0%);免疫组化结果显示,hPEBP-4在胰腺癌组织中的高表达率明显高于癌旁组织(80.0%vs. 16.7%,χ~2=24.093,P0.001)。hPEBP-4的表达水平与患者的肿瘤分化程度、CA19-9水平以及TNM分期有关(均P0.05)。相关性结果显示,胰腺癌分化程度、TNM分期均与hPEBP-4呈负相关(r=-0.507,P=0.004;r=-0.400,P=0.028),而血清CA19-9水平与hPEBP-4呈正相关(r=0.428,P=0.018)。生存分析结果显示,hPEBP-4低表达患者的总生存率明显高于高表达患者(χ~2=8.658,P=0.003)。结论:hPEBP-4在胰腺癌组织中表达升高,且与胰腺癌患者的部分恶性病理特征及不良预后密切相关。     

血红素氧合酶1在胰腺癌组织中的表达及临床意义

目的:探讨血红素氧合酶1(HO-1)在胰腺癌组织中的表达及临床意义。方法:分别用免疫组化法与Western blot法检测80例胰腺癌患者癌组织及癌旁组中HO-1的表达,通过统计学方法分析HO-1表达与胰腺癌患者临床病理特征及预后间的关系。结果:免疫组化与Western blot结果显示,胰腺癌组织HO-1蛋白的阳性表达率与相对表达量均明显高于癌旁胰腺组织(P0.05);HO-1在胰腺癌组织的表达与TNM分期、肿瘤分化程度及淋巴结转移明显有关(均P0.05),而与性别、年龄无明显关系(均P0.05);Log-rank检验显示,胰腺癌组织中HO-1阳性表达患者中位生存期明显低于其阴性表达患者(25.1个月vs. 36.7个月,P0.05)。结论:HO-1在胰腺癌组织呈高表达,且与胰腺癌的恶性临床特征及不良预后密切相关,可能成为胰腺癌治疗与研究的新靶点。     

TGFβ、HNF4α在原发性肝癌中的表达及临床意义

目的研究TGFβ和HNF4α在肝癌及癌旁组织中的表达,探讨其在肝癌发生、发展中的作用和意义。方法采用qRT-PCR和Western blotting方法检测54例原发性肝癌患者肝癌及对应癌旁组织中TGFβ和HNF4αmRNA及蛋白表达水平;免疫组化检测所有肝癌组织中TGFβ和HNF4α蛋白的表达水平,统计学分析两者与肝癌患者临床病理特征的关系。结果 (1)与癌旁组织比,TGFβmRNA在肝癌组织中表达升高[(0.294±0.142)vs(0.231±0.149),P=0.020];HNF4αmRNA在肝癌组织中表达降低[(0.104±0.130 vs(0.151±0.079),P=0.037];(2)Western blotting结果显示:与癌旁组织比,TGFβ蛋白在肝癌组织中高表达[(0.224±0.060)vs(0.051±0.019),P=0.025],HNF4α蛋白在肝癌组织中表达下降[(0.103±0.033)vs(0.315±0.024),P=0.017];(3)免疫组化检测显示,肝癌组织中TGFβ蛋白阳性表达率66.7%,HNF4α蛋白阳性表达率为57.4%。在肝癌组织中TGFβ蛋白表达水平与肿瘤分化(χ~2=4.339,P=0.037)及TNM分期(χ~2=4.488,P=0.034)相关;HNF4α蛋白与肿瘤分化(χ~2=5.032,P=0.025)相关。TGFβ蛋白与HNF4α蛋白呈负相关(r=-0.291,P=0.033)。结论 TGFβ和HNF4α基因相互调控EMT进程,参与原发性肝癌的发生发展。     

核基质结合蛋白1在胰腺导管腺癌中的表达及意义

目的 探讨胰腺导管腺癌(PDAC)中核基质结合蛋白1(SATB1)的mRNA和蛋白表达水平及其与临床病理特征的关系,评价SATB1在PDAC预后判断中的价值.方法 应用免疫组织化学法检测49例PDAC组织及配对的癌旁组织石蜡标本SATB1蛋白表达水平,利用Western blot 和反转录-聚合酶链反应(RT-PCR)检测16对配对冷冻保存的新鲜PDAC组织、癌旁组织中SATB1蛋白和mRNA表达水平.结果 免疫组织化学结果显示,SATB1在13例PDAC中呈高表达,癌旁组织有5例高表达(26.5％比10.2％).SATB1的表达与PDAC分化程度(x2=4.131,P＜0.05)、淋巴结转移(x2 =5.000,P＜0.05)、T分期(x2=14.348,P＜0.05)和TNM分期(x2=6.69,P＜0.05)相关.阳性表达SATB1的PDAC患者术后中位生存时间为353 d,阴性表达SATB1者为508 d.RT-PCR和Western blot结果显示SATB1在PDAC患者中mRNA表达高于癌旁组织(t=2.432,P＜0.05),蛋白表达水平差异无统计学意义(t=0.324,P＞0.05).结论 SATB1在PDAC中表达呈上调状态,与PDAC临床病理因素及预后相关.     

Tspan 1及Integrin α6在人胰腺导管腺癌中的表达及其与临床特征的关系

目的 探讨Tspan 1及Integrinα6在胰腺导管腺癌(PDAC)及胰腺癌细胞中的表达与临床病理学参数的关系.方法 收集2004年5月至2013年1月收治的95例PDAC患者的组织石蜡切片及55例癌旁正常组织石蜡切片进行免疫组化检测.以Western blot法和实时定量(qRT)-PCR法检测16对配对冷冻保存的新鲜PDAC、癌旁组织及6株胰腺癌细胞中Tspan 1及Integrin α6蛋白和mRNA表达水平.分别采用x2检验、Spearman-rank相关分析、Kaplan-Meier法、多因素回归分析等对数据进行统计分析.结果 Tspan 1及Integrinα6在PDAC细胞膜表达高于癌旁胰腺组织(x2=7.429,P＜0.05;x2=15.100,p＜0.01);Tspan 1表达与淋巴结转移、TNM分期及复发率呈正相关(x2=6.688,P＜0.01;x2=13.055,P＜0.01;x2 =6.116,P＜0.05).Integrin α6表达与TNM分期呈正相关(x2=8.896,P＜0.05);Tspan 1及Integrin α6的相关性有统计学意义(r=0.223,P＜0.05);Tspan 1及Integrin α6高表达与生存期呈负相关(x2=5.263,P＜0.05;x2=10.124,P＜0.01);多因素分析结果显示,Tspan 1及Integrinα6表达水平可以作为PDAC预后的独立预测因素(x2=6.152,P＜0.05;x2=9.479,P＜0.01).16例胰腺癌组织中Tspan 1及Integrin α6的蛋白(t=2.278,P＜0.05;t=3.153,P＜0.05)和mRNA(t=2.439,P＜0.05;t=3.258,P＜0.05)表达均高于配对的癌旁正常组织;6株细胞株中Tspan 1及Integrin α6在蛋白水平及mRNA水平均有表达,来自转移灶的人胰腺腺癌细胞株SW1990中Tspan 1及Integrin α6在蛋白及mRNA水平表达高于来自原发灶的细胞株(P＜0.05).结论 Tspan 1及Integrinα6表达对于PDAC的转移及浸润有促进作用,可能可以作为判断PDAC预后的独立因素.     

内质网氧化还原蛋白基因在胰腺癌组织中的表达及其与患者预后的关系

目的:探讨内质网氧化还原蛋白(ERO1L)在胰腺癌组织中的表达及临床意义。方法:用qRT-PCR技术检测ERO1L mRNA在82例胰腺癌组织以及12例胰腺癌旁组织中的表达,分析ERO1L mRNA表达水平与胰腺癌患者临床病理因素间以及无瘤生存期和总生存期的关系。结果:胰腺癌组织中ERO1LmRNA的相对表达量明显高于癌旁组织(2.63vs.1.12,P0.01);ERO1LmRNA表达与胰腺癌患者肿瘤分化程度、远处转移、临床分期和淋巴结转移有关(均P0.05),而与性别、年龄、肿瘤大小及部位无关(均P0.05);生存分析示ERO1LmRNA高表达患者1、3年无瘤生存率和总生存率均明显低于ERO1LmRNA低表达患者(P0.01);单因素和多因素分析显示,ERO1LmRNA表达量为胰腺癌患者术后无瘤生存和总生存的独立风险因素(均P0.05)。结论:ERO1L基因在胰腺癌组织中高表达,与胰腺癌的恶性临床病理特征密切相关,为胰腺癌患者预后的独立影响因子。     

YEATS域含蛋白质4在胰腺癌组织中的表达及预后意义

目的:探讨YEATS域含蛋白质4(YEATS4)胰腺癌组织中的表达及其与临床意义。方法:用手术切除且病理确诊的80例胰腺癌组织及对应癌旁组织标本构建组织芯片,利用免疫组织化学技术检测YEATS4在胰腺癌及癌旁组织中的表达情况。分析胰腺癌组织中YEATS4的表达与胰腺癌临床病理特征及胰腺癌患者预后的关系。结果:免疫组化结果显示,YEATS4在胰腺癌组织中的阳性表达率明显高于相应癌旁组织(56.25%vs.26.25%,P0.05)。YEATS4的阳性表达与胰腺癌患者的性别(P=0.037)、TMN分期(P0.001)、神经转移(P=0.006)、淋巴结转移(P0.001)以及脉管侵犯(P=0.042)明显有关。全组患者中YEATS4蛋白阴性表达患者生存率明显高于其阳性表达患者(χ~2=7.593,P=0.0059);亚组分析显示,YEATS4蛋白与不良预后的关系仅明显存在于TMN III/IV期、淋巴结转移、神经转移和脉管侵犯患者中(均P0.05)。YEATS4表达是胰腺癌患者预后的独立危险因素(HR=2.1,95%CI=1.1～4.2,P=0.026)。结论:YEATS4在胰腺癌中的表达量升高,可能参与了胰腺癌的进展,并可能是胰腺癌治疗的潜在预后标记和治疗靶点。     

B7-H1在胰腺癌免疫逃避中的作用研究

目的 检测B7-H1和IL-10在胰腺癌组织中的表达情况,并分析两者表达水平的相关性,以探讨肿瘤局部IL-10的异常增高和B7-H1表达的关系.方法 应用RT-PCR、Western blot和免疫组织化学法检测35例胰腺癌组织、相应癌旁组织和5例正常胰腺组织中B7-H1及IL-10的表达情况,并分析其相关性.结果 在胰腺癌、癌旁和正常胰腺组织中,B7-H1和IL-10在mRNA及蛋白水平的表达呈现出明显由高至低的趋势,且两两之间比较均具有明显差异(P<0.05),免疫组织化学结果也同样证实了胰腺癌中高表达B7-H1和IL-10,阳性率分别为60.5%±12.7%和65.3%±16.2%,而正常组织中未检测到表达.同时,相关性分析中显示肿瘤组织B7-H1高表达与IL-10水平呈明显正相关,分别表现在mRNA表达水平(P=0.008,r=0.841)和蛋白表达水平(P=0.007,r=0.838).结论 胰腺癌细胞上调表达B7-H1可能是肿瘤局部高浓度IL-10形成的原因之一,由此导致的抗肿瘤免疫能力降低可使肿瘤细胞逃避免疫系统的杀伤作用.     

组蛋白去甲基化酶含十字形结构域蛋白-3和核因子-κB高表达与肝细胞癌不良进展和预后的关系

目的观察肝细胞癌中组蛋白去甲基化酶含十字形结构域蛋白-3(JMJD3)和核因子-κB(NF-κB)蛋白水平的表达,探讨两者的相关性及其蛋白表达水平与多个临床病理因素的关系。方法采用实时荧光定量反转录-聚合酶链反应(RT-qPCR)法检测25例新鲜肝细胞癌组织及相对应的癌旁组织中JMJD3和NF-κB信使RNA(mRNA)表达,采用免疫组织化学法检测102例肝细胞癌及相对应的癌旁组织中JMJD3和NF-κB蛋白的表达,分析其与肝细胞癌临床病理特征的关系及上述蛋白的相关性,采用生存分析法(Kaplan-Meier)法来评估JMJD3和NF-κB蛋白的异常表达与肝细胞癌患者生存期之间的关系,Cox回归模型分析JMJD3和NF-κB蛋白的表达和临床病理参数与肝细胞癌预后的关系。结果JMJD3和NF-κB mRNA在肝细胞癌组织中的表达水平均高于癌旁组织(t=-15.130、-15.030,P<0.05),差异有统计学意义,肝细胞癌组织中JMJD3阳性率[87.25%(89/102)]显著高于相应癌旁组织[57.84%(59/102),χ²=22.153,P<0.05],差异有统计学意义,肝细胞癌组织中NF-κB阳性率[83.33%(85/102)]显著高于相应癌旁组织[29.41%(30/102),χ²=55.664,P<0.05],差异有统计学意义。JMJD3和NF-κB表达与甲胎蛋白水平、分化程度、有无脉管癌栓、淋巴结转移及TNM分期明显相关(P<0.05),NF-κB与结节数目明显相关(χ²=5.133,P<0.05),差异有统计学意义。JMJD3蛋白高表达者的生存期高于低表达者(χ²=40.568,P<0.05),差异有统计学意义,NF-κB蛋白高表达者的生存期低于低表达者(χ²=48.803,P<0.05),差异有统计学意义。Spearman相关分析结果显示JMJD3与NF-κB呈正相关(r=0.627,P<0.05)。结论JMJD3和NF-κB在肝细胞癌中的异常表达与肿瘤的浸润、转移及无病生存期明显相关。     

Rab25蛋白在胰腺癌组织中的表达及临床意义

探讨Rab25蛋白在胰腺癌组织中的表达及临床意义。应用免疫组化方法测定在37例胰腺癌和癌旁组织中Rab25蛋白的表达,分析Rab25蛋白与胰腺癌临床病理特征之间的关系。Rab25蛋白在胰腺癌组织中表达率为70.3%(26/37),在癌旁组织中的表达率为24.3%(9/37),两者差异有统计学意义(χ~2=15.67,P 0.01)。Rab25蛋白表达与胰腺癌的TNM分期、病理分级及有无淋巴结转移等因素相关(P 0.05);而与胰腺癌患者的年龄、性别、肿瘤位置及肿瘤大小均无关(P0.05)。Rab25蛋白在胰腺癌组织中呈高表达,其表达可能在胰腺癌的发生发展中起重要作用     

CYP1A1与GSTM1基因多态性与前列腺癌易感性的关系

目的　探讨CYP1A1、GSTM1基因多态性与前列腺癌遗传易感性的关系。　方法　采用寡核苷酸芯片对 83例前列腺癌患者和 115例正常对照的中国汉族人群基因组DNA进行CYP1A1、GSTM1基因多态性分析。　结果　GSTM1基因缺失型前列腺癌组占 5 7.8% ,对照组 4 1.7% ,差异有显著性意义 ( χ2 =4 .99,P =0 .0 2 5 ) ,GSTM1null基因型使患前列腺癌的危险度增加 1.9倍 ( 95 %CI=1.10～ 1.34)。GSTM1基因缺失型前列腺癌患者的平均年龄 [( 6 8.1± 8.3)岁 ]低于GSTM1未缺失的患者[( 71.9± 7.4 )岁 ,P =0 .0 31]。前列腺癌组CYP1A1基因的两个多态位点m1、m2基因型频率和等位基因的频率与对照组相比差异无显著性意义 (P >0 .0 5 )。　结论　中国汉族人群GSTM1基因多态性与前列腺癌的发生相关 ,可能是增加前列腺癌危险和发病年龄早的因素之一。CYP1A1基因m1和m2的基因多态与中国汉族人群前列腺癌的发生无相关性     

COL1A1 haplotypes and hip fracture

Fragility fractures resulting from low‐trauma events such as a fall from standing height are associated with osteoporosis and are very common in older people, especially women. Three single nucleotide polymorphisms (SNPs) at the COL1A1 gene (rs1107946, rs11327935, and rs1800012) have been widely studied and previously associated with bone mineral density (BMD) and fracture. A rare haplotype (T‐delT‐T) of these three SNPs was found to be greatly overrepresented in fractured individuals compared with nonfractured controls, thus becoming a good candidate for predicting increased fracture risk. The aim of our study was to assess the association of this haplotype with fracture risk in Spanish individuals. We recruited two independent groups of ～100 patients with hip fracture (a total of 203 individuals) and compared the genotype and haplotype distributions of the three SNPs in the fractured patients with those of 397 control individuals from the BARCOS Spanish cohort. We found no association with risk of fracture at the genotype level for any of the SNPs, and no differences in the SNP frequencies between the two groups. At the haplotype level, we found no association between the T‐delT‐T haplotype and fracture. However, we observed a small but significant (p = 0.03) association with another rare haplotype, G‐insT‐T, which was slightly overrepresented in the patient group. © 2012 American Society for Bone and Mineral Research.     

Genetic polymorphisms of CYP1A1, CYP2E1, GSTM1, and GSTT1 associated with head and neck cancer

BACKGROUND: Alcohol intake and tobacco smoke, in addition to other environmental and genetic factors, have been associated with head and neck cancer. We evaluated the role of metabolic enzyme polymorphisms on the risk of head and neck cancer in a hospital-based case-control study. METHODS: CYP1A1MspI, CYP2E1PstI, GSTM1, and GSTT1polymorphisms were evaluated in 103 histologically confirmed head and neck cancer cases and 102 controls by means of polymerase chain reaction-restriction fragment length polymorphism methods. RESULTS: GSTM1null increased the risk of head and neck cancer (odds ratio [OR], 2.2; 95% confidence interval [95% CI], 1.24-3.79), oral cancer (OR, 2.8; 95% CI, 1.28-5.98), and pharyngeal cancer (OR, 2.2; 95% CI, 1.08-4.63). CYP2E1PstI polymorphism indicated a risk for oral cancer (OR, 3.6; 95% CI, 1.29-11.56). The joint effect of GSTM1 null and CYP1A1 polymorphism increased the risk of head and neck cancer (OR, 2.4; 95% CI, 1.13-5.10). CONCLUSIONS: GSTM1 null alone or associated with CYP1A1 increased the risk of head and neck cancer; the CYP2E1PstI mutated allele increased the risk for only oral cancer.     

Tumors with EWSR1-CREB1 and EWSR1-ATF1 fusions: the current status

EWSR1-CREB1 and EWSR1-ATF1 are gene fusions of which one or both have now been consistently described in 5 histopathologically and behaviorally diverse neoplasms: angiomatoid fibrous histiocytoma, conventional clear cell sarcoma (of tendons and aponeuroses), clear cell sarcoma-like tumor of the gastrointestinal tract, hyalinizing clear cell carcinoma of the salivary gland, and primary pulmonary myxoid sarcoma. Some of the tumors in this group have been described only recently, and others have been the subject of recent genetic insights contributing to their characterization. These neoplasms are all rare; yet, the increasing frequency with which EWSR1-CREB1 and EWSR1-ATF1 fusions are being described in separate entities is noteworthy. The additional molecular mechanisms by which tumors with such variable morphologic, immunohistochemical, and clinical phenotypes are generated are yet to be understood. We review the clinicopathologic and molecular features of this group of neoplasms unified by the presence of EWSR1-CREB1 and EWSR1-ATF1 genetic fusions.     

Impact of CYP1A1, GSTM1, and GSTT1 polymorphisms in overall and specific prostate cancer survival

ObjectivePrognostic biomarkers that distinguish between patients with good or poor outcome can be used to guide decisions of whom to treat and how aggressively. In this sense, several groups have proposed genetic polymorphisms as potential susceptibility and prognostic biomarkers; however, their validity has not been proven. Thus, the main goal of the present work was to investigate the potential role of single and combined CYP1A1, GSTM1, and GSTT1 genotypes as modifiers of cancer survival in Chilean patients with prostate cancer.Methods and materialsA total of 260 histologically confirmed patients were recruited from a voluntary screening, and genomic DNA was obtained from their blood samples for genotyping analyses to detect the CYP1A1*2A polymorphism and GSTM1 and GSTT1 deletions. The progression of illness and mortality were estimated with a median follow-up of 8.82 years. Adjusted estimated genotype risks were evaluated by hazard ratio and 95% CI using the Cox proportional model. In addition, the Kaplan-Meier survival method and log-rank test were used to evaluate patient survival with regard to genotype.ResultsThe 9-year overall and specific survival rates were 67.6% and 36.6% in the GSTT1null group, 67.6% and 58.7% in the GSTM1non-null group, 69.0% and 51.6% in the *1A/*2A group, 63.9% and 61.5% in the *2A/*2A group vs. 76.2% and 62.3% in the GSTT1non-null group, 82.3% and 50% in the GSTM1null group, and 83.7% and 56.3% in the *1A/*1A group, respectively. The hazard ratios and the Kaplan-Meier curve results demonstrate that the GSTM1non-null, GSTT1null, and CYP1A1*2A genotypes are significantly associated with mortality. Our study has two main limitations: a relatively small sample size and a low global mortality percentage (25.4%); thus, we need to continue the follow-up to confirm these findings.ConclusionsOur results suggest that the GSTM1non-null, GSTT1null, and CYP1A1*2A genotypes may be good prognosis markers, particularly in patients with high-risk tumors.     

DQA1 and DQB1 association and nasal polyposis.

OBJECTIVE: The aim of this study was to determine the contribution of the human major histocompatibility complex (HLA)-DQA1, -DQB1, and TNFalpha genes with simple nasal polyposis. STUDY DESIGN AND SETTING: A comparative case-control study with 31 patients and 151 controls was performed. HLA-DQA1, -DQB1, and TNFalpha -238 promoter position loci were typed by polymerase chain reaction (PCR) and sequence specific oligonucleotide probes (SSOPs). TNFalpha -308 promoter position was determined by PCR and digestion with NcoI restriction enzyme. RESULTS: The allele HLA-DQA1*0201 (P(c) = 0.019) had an etiologic fraction (EF) of 17%, whereas 13% EF was found for the haplotype HLA-DQA1*0201-DQB1*0201 (P = 0.016). Analysis of -DQB1 and TNFalpha promoter did not show significant differences between cases and controls. CONCLUSIONS: HLA-DQA1*0201-DQB1*0201 haplotype is involved in susceptibility, conferring 5.53 times more risk of developing this disease. EBM rating: B-2b.     

GSTT1, GSTM1, and CYP1B1 gene polymorphisms and susceptibility to sporadic renal cell cancer

PurposeTo estimate the prevalence and importance of GSTT1, GSTM1, and CYP1B1 genotypes in renal cell carcinoma (RCC), and to identify their value as a prognostic factor.Materials and methodsCross-sectional study of a group of patients diagnosed with RCC (n = 133) and a control group (n = 208) with benign conditions and no history of tumor. Controls were selected by cumulative samples and mixed pairing. All subjects pertained to the catchment area for our hospital. Sociodemographic variables, anatomical pathology features, and presence of GSTT1, GSTM1, and CYP1B1 polymorphisms by multiplex PCR and sequencing techniques.ResultsThere were no differences in the genotype distribution of the GSTT1 and GSTM1 genes between cases and controls. In the case of CYP1B1, the GG genotype (Ala119) was more prevalent in patients with RCC (OR = 2.08; 95% CI: 1.32–2.28) and may be implicated in 34.3% (95% CI: 16.3–52.2) of RCCs. In patients with GSTT1 deletion, TNM stages III to IV were more common (39.1%); whereas in Val432 homozygous patients in CYP1B1, Fuhrman grades 3 to 4 (54.6%) were more common. Because this was a cross-sectional study, longitudinal studies are needed in the future to confirm these data.ConclusionsNo relationship between GSTT1 and GSTM1 genotypes and RCC risk was observed. Homozygous subjects with Ala119 in CYP1B1 had twice the risk of RCC as homozygous for Ser119 or heterozygotes. Patients with GSTT1 deletion had tumors of more advanced stages, and those with Val432 polymorphism in CYP1B1 had tumors of higher Fuhrman grade.     

The HLA-DPB1--associated component of the IDDM1 and its relationship to the major loci HLA-DQB1, -DQA1, and -DRB1

The major histocompatibility complex (MHC) HLA region on chromosome 6p21 contains the major locus of type 1 diabetes (IDDM1). Common allelic variants at the class II HLA-DRB1, -DQA1, and -DQB1 loci account for the major part of IDDM1. Previous studies suggested that other MHC loci are likely to contribute to IDDM1, but determination of their relative contributions and identities is difficult because of strong linkage disequilibrium between MHC loci. One prime candidate is the polymorphic HLA-DPB1 locus, which (with the DPA1 locus) encodes the third class II antigen-presenting molecule. However, the results obtained in previous studies appear to be contradictory. Therefore, we have analyzed 408 white European families (200 from Sardinia and 208 from the U.K.) using a combination of association tests designed to directly compare the effect of DPB1 variation on the relative predisposition of DR-DQ haplotypes, taking into account linkage disequilibrium between DPB1 and the DRB1, DQA1, and DQB1 loci. In these populations, the overall contribution of DPB1 to IDDM1 is small. The main component of the DPB1 contribution to IDDM1 in these populations appears to be the protection associated with DPB1*0402 on DR4-negative haplotypes. We suggest that the HLA-DP molecule itself contributes to IDDM1.