Genetic Epidemiological Studies Of Nasopharyngeal Cancer

鼻咽癌（NPC）在中国南方和台湾比世界其他地区更常见。Epstein-Barr病毒被怀疑在疾病病因学中发挥作用，但支持数据非常有限。该疾病表现出明显的家族聚集性，我们以前报道的分离分析表明，一个reckless传播的主基因可能参与。我们目前的研究旨在使用分子流行病学方法确定这种疾病的基本原因。我们从大量的受试者中获得了关于这种疾病的家族史及其与危险因素相关性的问卷调查数据。到目前为止，我们已经从297个家庭中的1,449名受试者中获得了DNA、血清、口腔冲洗液、口腔刷和唾液，这些家庭中有两名或两名以上的成员受到NPC的影响。我们还从我们的多重家庭成员中获得了1，645份风险因素问卷。对所有研究受试者的血清样本进行爱泼斯坦巴尔病毒（EBV）抗体滴度评估。使用Applied Biosystems 2.0版的高信息量短串联重复序列（STR）标记，已完成了约767份DNA样本的全基因组扫描。与NCI的科学家合作，包括HLA变体在内的候选基因SNP的实验室测定也在进行中。我们使用荧光标记的寡核苷酸引物在PCR过程中纳入。通过在Applied Biosystems（Perkin Elmer）Model 373和377自动DNA分析仪上变性PAGE来确定产物大小。使用GENESCAN和GENOTYPER计算机程序（Applied Biosystems）从凝胶图像鉴定微卫星等位基因。使用被认为是最强大和强大的复杂疾病的方法对这些数据进行统计分析，已经确定了几个基因和染色体区域，这些基因和染色体区域是非常有前途的候选者，对NPC易感性个体之间的差异有重大影响。有些分析是一般性的，正应用于分支研究的所有复杂疾病。其他分析涉及NPC特异性的新方法，例如使用EBV滴度作为预测NPC风险的协变量。正在对正在检测的候选基因进行传递不平衡试验（TDT），包括HLA基因座和CYP 2 E1的SNP，这些基因先前已被认为与NPC的风险相关。正在评估从所有参与研究的受试者中收集的广泛问卷数据，以确定这种疾病最重要的环境风险因素。这些分析将使用解释家庭成员之间关系的统计方法。EB病毒抗体滴度被分析为直接感兴趣的因变量，以了解宿主防御的遗传基础。这些免疫应答表型的基因定位研究需要最小的额外成本，因为生物标本和大量的基因型已经可用于这些受试者。石蜡包埋的肿瘤组织切片从大约一半的NPC病例中获得，用于分子分析。

Nasopharyngeal carcinoma (NPC) occurs much more commonly in southern China and Taiwan than in other parts of the world. Epstein-Barr virus is suspected to play a role in disease etiology, but supporting data are quite limited. The disease exhibits clear familial aggregation, and our previously reported segregation analyses suggest that a recessively transmitted major gene may be involved. Our current studies are aimed at determining the basic causes of this disease using molecular epidemiological approaches. We have obtained questionnaire data regarding the family history of this disease and correlation with risk factors from a large number of subjects. To date, we have obtained DNA, serum, oral rinses, oral brushes and saliva for 1,449 subjects from 297 families identified with two or more members affected by NPC. We also obtained 1,645 risk factor questionnaires from our multiplex family members. Epstein Barr Virus (EBV) anitbody titres are being assessed on serum samples from all study subjects. A whole genome scan has been completed for approximately 767 DNA samples using highly informative Short Tandem Repeat (STR) markers of the Applied Biosystems Version 2.0 set. Laboratory assays of candidate gene SNPs including HLA variants are also ongoing, in collaboration with scientists at the NCI. We used fluorescently labeled oligonucleotide primers incorporated during PCR. Products were sized by denaturing PAGE on Applied Biosystems (Perkin Elmer) Model 373 and 377 automated DNA analyzers. GENESCAN and GENOTYPER computer programs (Applied Biosystems) were used to identify microsatellite alleles from the gel images. Statistical analyses of these data using methods thought to be most powerful and robust for complex diseases have identified several genes and chromosomal regions that are very promising candidates for having major influence on differences among individuals in susceptibility to NPC. Some analyses are general and are being applied to all complex diseases under study in the Branch. Other analyses involve novel approaches specific for NPC such as using EBV titres as covariates for predicting NPC risk. Transmission disequilibrium tests (TDTs) are being performed on the candidate genes being assayed including SNPs at HLA loci and CYP2E1 that have been previously suggested to be associated with the risk of NPC. Extensive questionnaire data collected for all participating subjects are being evaluated to identify the most important environmental risk factors for this disease. Statistical methods which account for relationships among family members will be used for these analyses. EBV antibody titres are being analyzed as a dependent variable of direct interest for understanding the genetic basis of host defense. Gene mapping studies of these immune response phenotypes have required minimal additional cost, since biospecimens and substantial numbers of genotypes are already available for these subjects. Sections from paraffin-embedded tumor tissue are being obtained from approximately half of these NPC cases for molecular analyses.