食管癌组织3p、18q位点微卫星DNA序列不稳定性的研究

目的:探讨微卫星DNA序列不稳定性(M SI)表达水平与人食管癌发生及其临床病理特征的关系。方法:应用聚合酶链反应(PCR)和变性聚丙烯酰胺凝胶电泳技术,对30例人食管癌中M SI表达情况进行研究。结果:D3S1067位点M SI发生检出频率较高,为26.7%(8/30);D18S58位点M SI阳性率为20%(6/30)。有18对组织在D3S1067和D18S58两个位点均未检出M SI。食管癌M SI多发生在3p位点,尤其是在3p14～3p21区段。食管鳞癌组织中M SI阳性为26.1%(6/23),差异有显著性(P0.05)。结论:食管癌在3p和18q染色体位点均存在微卫星不稳定现象;D3S1067和D18S582个位点上M SI与食管癌的临床病理类型均相关:D3S1067位点M SI与食管鳞癌的发生关系密切,D18S58与食管小细胞癌的发生关系密切;M SI也许可做为临床筛查恶性肿瘤高危人群的分子手段,具有潜在的应用前景。     

CD44v5 mRNA在新疆维吾尔族、汉族食管鳞癌中的表达及其临床病理学意义

目的:探讨新疆维吾尔族和汉族食管鳞癌中CD44v5 mRNA的表达情况以及与临床病理特征之间的关系.方法:利用RT-PCR技术检测食管鳞癌组织60例(维族、汉族各30例),及其对应的正常食管上皮组织60例中CD44v5 mRNA表达的情况.结果:CD44v5 mRNA在维吾尔族食管鳞癌组织及正常组织中的阳性表达率分剐为86.67%和46.67%(P=0.003):在汉族食管鳞癌组织及正常组织中的阳性表达率分别为96.67%和50.00%(P=0.000);但在两民族间的表达差异无统计学意义(P=0.930):CD44v5 mRNA的表达与TNM分期及淋巴结转移相关(P<0.05).结论:CD44v5 mRNA表达与食管癌发生发展有关,可作为食管癌转移及预后不良的生物学指标.     

食管癌患者多个染色体区域的杂合性缺失及其临床意义

目的 选择食管癌中遍布10个染色体区域的17个微卫星位标,进行食管癌手术切除标本的微卫星杂合缺失(LOH)分析,并探讨这些位点的LOH与患者临床病理参数之间的关系.方法 68份食管癌患者手术切除的鳞癌组织标本中,高分化鳞癌20份,中分化鳞癌30份,低分化鳞癌18份.采用PCR荧光测序法和凝胶电泳分别检测68例患者的鳞癌组织及匹配的外周血样本中17个微卫星位点的杂合性缺失状况;并比较分析LOH与肿瘤临床病理参数之间的关系.结果 68份标本中检出位点D8S261 LOH频率最低(33.3%),检出位点D9S125 LOH频率最高(85.2%),其中,12个位标LOH频率高于50.0%,3个(D3S1597、D3S1285、D9S125)高于75.0%;分化程度不一的肿瘤标本在位点D9S111与D13S153处的LOH频率差异有统计学意义(χ2=15.5、10.8,P均<0.05),位点D9S111处高分化的12份标本中发生缺失2份,中分化20份标本中发生缺失14份,低分化16份标本中发生缺失14份,位点D13S153处8份高分化标本中2份发生缺失,中分化的28份标本中12份发生缺失,低分化的12份标本中11份发生缺失;发生淋巴结转移的肿瘤标本与未转移标本在位点D8S261处的LOH频率差异有统计学意义(χ2=6.4,P<0.05),位点D8S261处发生转移的14份标本中1份出现缺失,未转移的22份标本中12份出现缺失.结论 食管鳞癌中存在广泛、高频的LOH,位于高频缺失位点附近的基因可能参与了食管癌的发生发展;位点D9S111和D13S153处的缺失与食管癌的病理分级有显著的相关性,分化越差的标本在2位点处缺失频率倾向越高;位点D8S261处的缺失与食管癌淋巴结转移呈反向相关,在该处发生缺失的标本淋巴结转移的可能性往往较低.     

食管鳞癌组织中nm23基因表达及其临床意义的研究

研究食管鳞癌组织中nm2 3基因表达与肿瘤生物学行为之间的关系。方法 :应用免疫组织化学S -P法检测 43例食管癌手术切除标本中nm2 3基因的表达水平。结果 :食管鳞癌组织中nm2 3基因表达阳性率为 74 4% ( 3 2 /4 3 ) ,其表达水平与癌浸润深度和TNM分期有关 ( P <0 0 5 )。早期病例nm2 3基因表达明显低于中晚期食管癌。有淋巴结转移者均为高表达。结论 :nm2 3基因过度表达与食管鳞癌的浸润深度、TNM分期、淋巴结转移有关。nm2 3基因表达可作为中晚期食管癌预后判断的参考指标之一 ,过度表达提示预后不良。     

中国南方汉族人群D2S1338和D19S433基因座遗传多态性及其应用

为了研究中国南方汉族人群中D2S1338和D19S433基因座遗传多态性，并应用于常规法医学亲子鉴定，采用chelex-100法提取基因组DNA，Identifiler^TM试剂盒对D2S1338等15个常染色体STR基因座进行复合扩增，扩增产物经AB13100 DNA测序仪电泳并收集电泳信息，用GeneScan3．0和Genetype3．7软件分析受检者的STR基因型，统计分析D2S1338和D19S433基因座的基因频率等基础数据。结果表明：获得了D2S1338、D19S433两个STR基因座各等位基因的基因频率、杂合度（H）、个体识别率（Dp）、多态信息量（PIC）及非父排除率（PE）等基础数据；基因频率经x^2检验，符合Hardy—Weinberg平衡。观察185例认定亲子关系案例计370次减数分裂，未观察到D2S1338、D19S433基因的突变。结论：D2S1338和D19S433基因座在中国南方汉族人群中有较好的基因型分布，多态信息量高，突变率低，适用于作为法医学亲子鉴定、个体识别的遗传标记。     

五聚素3基因甲基化在食管鳞癌中的作用

目的研究食管鳞癌组织中五聚素3(PTX3)基因的表达,以及基因启动子区甲基化状态对其表达的影响。方法应用半定量逆转录PCR(RT-PCR)、甲基化特异性PCR(MSP)、免疫组织化学的方法对癌旁食管黏膜组织和食管鳞癌组织进行检测,分析PTX3基因mRNA的表达、基因启动子区甲基化状态和PTX3蛋白阳性表达与食管癌临床病理特征的关系。结果 25%(5/20)食管鳞癌组织和90%(18/20)正常食管黏膜组织存在PTX3基因表达,PTX3mRNA在食管癌与癌旁组织之间的表达差异有统计学意义(χ2=17.289,P<0.001)。80%(16/20)食管鳞癌组织和25%(5/20)正常食管黏膜组织存在PTX3基因CpG岛超甲基化,提示PTX3基因超甲基化与食管癌发生之间有关联(χ2=12.13,P<0.001)。PTX3蛋白在食管癌组织中表达的阳性率为30.38%(24/79),癌旁食管组织PTX3蛋白阳性表达率为84.81%(67/79)(P<0.001)。随着食管癌临床分期增加,PTX3蛋白阳性表达率逐渐降低。结论 PTX3基因启动子高甲基化是PTX3表达失活的主要原因,在食管鳞癌的发生发展中起重要作用,PTX3基因启动子甲基化可作为食管鳞癌预后评估的潜在肿瘤标志物。     

PDCD5和Smac在食管鳞癌中的表达及其临床意义

目的:探讨食管鳞癌组织中PDCD5和Smac蛋白的表达及其临床意义.方法:应用免疫组化方法检测58例食管鳞癌组织和23例癌旁组织中PDCD5和Smac的表达,分析两者的表达水平与临床病理特征的关系以及两者的相互关系.结果:PDCD5在食管鳞癌组织中的阳性率为41.4%,明显低于癌旁组织78.3%(P<0.05),其表达与TNM分期、淋巴结转移相关性均有统计学意叉(P<0.05).Smac在食管鳞癌组织中的阳性率为32.8%,明显低于癌旁组织73.9%(P<0.05),而与肿瘤的分化程度、TNM分期、淋巴结转移的相关性均有统计学意义(P<0.05).PDCD5和Smac蛋白表达呈正相关关系(r=0.416,P<0.05).结论:PDCD5和Smac蛋白在食管鳞癌中表达下调,提示PDCD5与Smac蛋白的改变可能与食管癌的发生、发展相关.从而可为食管鳞癌的诊断及预后提供参考.     

miRNA-21-5P在食管鳞癌患者中的鉴别诊断价值

目的检测食管癌患者血清miRNA-21-5P的表达水平,探讨miRNA-21-5P对食管癌患者的鉴别诊断价值。方法选取2019年12月至2020年3月于朝阳市中心医院就诊的食管鳞癌患者50名(疾病组)及食管炎患者20名(相关疾病对照组),采集食管炎患者血清样本及组织样本,以及食管鳞癌患者治疗前血清样本、术中食管鳞癌组织及癌旁组织。通过实时荧光定量PCR(qRT-PCR)检测2组血清及组织样本中miRNA-21-5P的表达水平,分析miRNA-21-5P表达水平与食管鳞癌患者临床病理参数的关系,采用ROC曲线评估其对食管鳞癌的鉴别诊断价值。结果食管鳞癌患者血清miRNA-21-5P的表达水平(3.60±0.09)显著高于食管炎患者(1.01±0.05),差异有统计学意义(t=24.43,P0.05);食管鳞癌患者癌组织中miRNA-21-5P的表达水平(4.36±0.29)显著高于癌旁组织(1.31±0.16),差异亦具有统计学意义(t=20.10,P0.05);而食管癌患者组织中miRNA-21-5P的表达水平显著高于食管炎患者组织(t=20.100,P0.05)。ROC曲线分析结果显示,组织中miRNA-21-5P筛查食管鳞癌的ROC曲线下面积(AUC~(ROC))为0.767(95%CI:0.650,0.859),当cut-off值为0.39时,其敏感性88%,特异性为75%。血清miRNA-21-5P筛查食管鳞癌的AUC~(ROC)为0.671(95%CI:0.549,0.779),当cut-off值为0.63时,其敏感性为80%,特异性为66%。结论 miRNA-21-5P在食管鳞癌血清中的诊断价值与组织相当,或可用于对食管鳞癌的鉴别诊断。     

XIAP蛋白在食管鳞癌中的表达及意义

目的:观察XIAP蛋白在食管鳞癌组织中的表达,探讨XIAP与食管鳞癌的相关性.方法:应用免疫组织化学方法检测168例食管鳞癌组织和30例癌旁正常食管黏膜组织XIAP蛋白的表达.结果:食管鳞癌组织中XIAP蛋白的阳性表达率为78.6%(132/168),正常食管黏膜组织中XIAP蛋白的阳性表达率为16.7%(5/30),XIAP蛋白阳性表达率在食管鳞癌组织和正常食管黏膜组织中差异具有统计学意义(P ＝ 0.000),XIAP蛋白表达与食管鳞癌组织学分级、临床分期和淋巴结转移情况具有一定关系(P ＝ 0.005、P ＝ 0.023、P ＝ 0.013).结论:XIAP表达异常在食管鳞癌发生发展中具有重要作用,检测XIAP的表达对判断食管鳞癌的预后具有重要意义,XIAP有可能成为食管癌基因治疗新的靶标.     

NKG2A、NKG2D在食管鳞癌不同病理分期的表达及其相关性分析

目的 分析不同病理分期食管鳞癌患者血清中自然杀伤细胞表面抑制性受体A(NKG2A)和自然杀伤细胞表面活化性受体D(NKG2D)表达水平的特点,探讨NKG2A和NKG2D在食管鳞癌不同病理分期的表达意义,并研究NK细胞、NKG2A、NKG2D与病理分期的相关性.方法 用流式细胞仪分析92例食管鳞癌患者及50例健康志愿者外周血NK细胞数量及其NKG2A和NKG2D的表达情况.结果 与正常对照组相比,食管鳞癌患者外周血NK细胞表达增加[(9.97±4.25)% vs.(16.22±8.91)%,t′=-5.646,P<0.01],NK细胞表面NKG2A的表达水平升高[(35.19±17.73)% vs.(47.35±18.88)%,t=-3.742,P<0.01],NKG2D的表达水平降低[(83.20±3.85)% vs.(80.60±9.09)%,t′=1.925,P=0.019];食管鳞癌患者NKG2A/NKG2D的比值与其病理分期呈正相关性(r=0.333,P<0.01),行线性回归分析得F=7.413,P=0.008,按α=0.05水准,回归方程为:Y(NKG2A/NKG2D的比值)=0.105X(食管鳞癌病理分期)+0.347;R2=0.276.结论 食管鳞癌患者机体NK细胞数目增多,NKG2A/NKG2D比值与食管鳞癌病理分期进展呈正相关;降低NKG2A,提高NKG2D的表达水平,能增强NK细胞对肿瘤的杀伤活性,从而为食管鳞癌的免疫治疗开创新的思路.     

急性髓细胞白血病17号染色体短臂杂合性缺失的研究

目的探讨17号染色体短臂(17p13.3)的杂合性缺失(LOH)在急性髓细胞白血病(AML)中的作用。方法采用聚合酶链反应扩增、聚丙烯酰胺凝胶电泳和硝酸银染色技术,研究17p13.3上的D17S1866、D17S695、D17S849、D17S926、D17S643微卫星位点的LOH。结果 30例AML患者中发生LOH的共有17例(56.7%)25例次,D17S1866、D17S695、D17S849、D17S926、D17S643位点LOH的发生率依次为23.3%(7/30)、23.3%(7/30)、16.7%(5/30)、13.3%(4/30)和6.7%(2/30)。其中2例同时在D17S1866、D17S849位点发生LOH;2例同时在D17S1866、D17S695位点发生LOH;1例同时在D17S695、D17S849位点发生LOH;1例同时在D17S695、D17S926位点发生LOH;1例同时在D17S1866、D17S849、D17S643位点发生LOH。10例健康对照者均未发生LOH。结论 17p13.3上D17S1866、D17S695、D17S849、D17S926、D17S643位点可检测到较高频率的LOH,提示该区域的LOH可能在AML的发生中有一定作用。     

Identification of loss of heterozygosity on circulating free DNA in peripheral blood of prostate cancer patients: potential and technical improvements

BACKGROUND: Accurate identification of loss of heterozygosity (LOH) on circulating free DNA is often restricted by technical limitations such as poor quality and quantity of tumor-specific DNA and contamination by normal DNA. However, plasma DNA may harbor tumor-specific genetic alterations and could therefore be an interesting target for noninvasive examinations of tumor DNA. METHODS: By PCR-based fluorescence microsatellite analysis using 12 polymorphic markers, we investigated LOH on cell-free DNA in blood plasma from 59 patients with localized prostate cancer (PCa) and 12 with metastatic disease (MPCa). In addition, plasma DNA from 21 PCa patients was fractionated into high- and low-molecular-weight DNA by 2 different column systems. To avoid appearance of artificial allelic loss and stabilize the amplification, TMAC (tetramethylammonium chloride) was added to each PCR. RESULTS: Overall incidences of LOH at all markers analyzed were 10% in PCa and 12% in MPCa samples. Highest frequencies were found at markers D11S898 (28%) in PCa and D6S1631 (27%) in MPCa. Statistical evaluation showed significant associations between LOH and increasing Gleason scores for the marker combinations D6S1631*D8S286*D9S171 (P = 0.03) and D8S286*D9S171 (P = 0.05). Fractionation of plasma DNA resulted in a higher overall LOH frequency in the low-molecular-weight DNA fraction (23%) compared with the high-molecular-weight DNA (7%). CONCLUSIONS: LOH analysis of circulating DNA can provide tumor-specific genetic information on PCa patients. Fractionation of plasma DNA and addition of TMAC improved LOH detection and general assay performance.     

微卫星标志在检测白血病抑癌基因缺失中的应用

目的 用微卫星标记技术寻找与白血病发生相关的候选抑癌基因。方法 用聚合酶链反应（PCR）扩增方法检测28例白血病患者11号染色体短臂四个微卫星位点的杂合性缺失频率。结果 18例急性白血病患者中，8例（44．4％）在11号染色体短臂上出现了至少1个位点的杂合性缺失（LOH）；10例慢性白血病患者中未检出所选位点的LOH。其中位点D11S1334（位于11p15.4-p15.2)的LOH率为27．8％（5／18），位点D11S1331（位于11p15.4-p15.1)的LOH率为22．2％（4／18）。位点D11S922（位于11p15.5)LOH率为22．2％（4／18），且有75％（3／4）的患者同时存在该位点与其它位点的改变。结论 在11p15.2-p15.5区域可能存在候选的抑癌基因。     

血浆DNA在肺癌诊断上的意义

目的研究血浆DNA 3P D3S1300和D3S1289位点杂合性缺失(LOH)作为肿瘤标志物在肺癌诊断中的意义.方法收集初诊69例肺癌患者全血及肿瘤组织,40例非肺癌病人全血,用PCR-银染法分析肿瘤患者血浆、肿瘤组织中及对照组血浆中DNA D3S1300和D3S1289 LOH情况,观察阳性率.结果 69例肺癌患者肿瘤组织DNA中D3S1300和D3S1289的LOH检出率分别为40.6%和31.9%,血浆检出率为29.0%和24.6%.对照组血浆仅有2例DNA检出D3S1300 LOH,3例检出D3S1289 LOH.与肺癌组相比P＜0.01.结论血浆DNA LOH可望作为一种新的肿瘤标志物.     

膀胱肿瘤6号染色体长臂的杂合性缺失研究

目的探讨 6号染色体长臂的杂合性缺失 (LOH)与膀胱肿瘤的关系。方法应用 6q2 1区域附近D6S40 4、D6S43 4微卫星标志 ,以PCR SSLP 银染法对 3 1例膀胱肿瘤患者的肿瘤组织进行杂合性缺失的研究。结果膀胱肿瘤组织D6S40 4LOH发生率为 3 5 5 %,D6S43 4LOH发生率为 2 2 6%。结论 6q2 1区域附近可能存在与膀胱肿瘤相关的肿瘤抑制基因。     

Comparison of allelic ratios from paired blood and paraffin-embedded normal tissue for use in a polymerase chain reaction to assess loss of heterozygosity.

BACKGROUND: One method to assess loss of heterozygosity (LOH) of various genes is the amplification of DNA from neoplastic tissue by using microsatellite markers. LOH can best be considered on a quantitative basis as a comparison of allelic ratios of neoplastic tissue to that of the normal control. We will illustrate through quantitative methods the importance of using the appropriate controls when determining allelic loss. METHODS AND RESULTS: DNA extracted from 28 paired blood and formalin-fixed, paraffin-embedded normal mucosal tissue was amplified using the DP1 microsatellite marker, consisting of a variable number of CA repeats. This marker is located within the D5S346 (DP1) region on chromosome 5 and is linked to the adenomatous polyposis coli gene. Allelic ratios were calculated after scanning autoradiographs on a densitometer. Ratio values approaching 1 were observed when the two alleles were close in molecular weight, whereas ratios less than 1 were detected when the two alleles had very different molecular weights. This discrepancy was more pronounced in paraffin-embedded tissue than with blood samples. CONCLUSION: For LOH amplification assays, it is best to use normal control samples that are of the same tissue source as the neoplastic sample being analyzed. When assessing LOH in neoplastic tissue, a quantitative value rather than visual assessment of the alleles should be considered. The values may be normalized by dividing the ratio of the two tumor alleles by the ratio of the two normal alleles.     

儿童急性淋巴细胞白血病6q16.3微卫星DNA缺失及生物信息学分析

目的定位儿童急性淋巴细胞白血病（ALL）杂合性缺失（LOH）的集中区域,探索新的肿瘤抑制基因.方法取6q16.3的15个微卫星标记,用聚合酶链反应-变性凝胶电泳-银染技术对165例ALL患儿等位基因LOH的情况进行生物信息学分析;同时分析其与临床预后因素的相关性.结果至少1个位点的LOH率为32.7%,D6S1709-D6S1028及D6S2160-D6S1580是高频率集中缺失的区域,早期复发患儿的LOH率高于无早期复发患儿;谷氨酸受体6基因（GRIK2）可能为抑癌基因,2个区域存在可能代表新基因的表达序列标签12个.微卫星LOH与白细胞计数、病态细胞数、核型分析、早期复发均有相关性（P值均＜0.05）.结论D6S1709-D6S1028和D6S2160-D6S1580为目前国内外所确定的最精确缺失区,该区域可能存在1个或数个肿瘤抑制基因,6q16.3的LOH的发生与ALL预后有一定关系.     

Genetic Heterogeneity in Saliva from Patients with Oral Squamous Carcinomas: Implications in Molecular Diagnosis and Screening

We performed microsatellite analysis at chromosomal regions frequently altered in head and neck squamous carcinoma on matched saliva and tumor samples from 37 patients who had oral squamous carcinoma. The results were correlated with the cytologic findings and traditional clinicopathologic factors to assess the diagnostic and biological potential of these markers. Our data showed that 18 (49%) of the saliva samples and 32 (86%) of the tumors had loss of heterozygosity (LOH) in at least one of the 25 markers studied. In saliva, the combination of markers D3S1234, D9S156, and D17S799 identified 13 (72.2%) of the 18 patients with LOH in saliva (P < 0.001). For tumors, markers D3S1234, D8S254, and D9S171 together identified 27 (84.3%) of the 32 tumors with LOH at any of the loci tested (P < 0.001). Eleven (55%) of the 20 saliva samples with cytologic atypia and seven (35%) of the 17 specimens without atypia had LOH. Significant correlation between LOH in tumor at certain markers and smoking and alcohol use was found. Our results indicate that: 1) epithelial cells in saliva from patients with head and neck squamous tumorigenesis provide suitable material for genetic analysis; 2) combined application of certain markers improves the detection of genetic alteration in these patients; 3) clonal heterogeneity between saliva and matching tumor supports genetic instability of the mucosal field in some of these patients; and 4) LOH at certain chromosomal loci appears to be associated with smoking and alcohol consumption.     

Molecular studies of loss of heterozygosity in Chinese sporadic retinoblastoma patients

BACKGROUND: Retinoblastoma, an embryonic neoplasm of retinal origin, is the most common and severe intra-ocular tumor affecting infants and young children. METHODS: Loss of heterozygosity (LOH) on chromosome 13 was investigated in 16 Chinese sporadic RB patients, using 14 microsatellite markers spanning the complete chromosome 13, to determine whether those alterations different from the alteration of RB1 gene on 13q14 may play a role in the development of RB. Loss of RB1 allele is commonly encountered in sporadic RB. Microdissected RB tissues and their matched blood DNAs were analyzed for PCR-based LOH by using fluorescence-based DNA sequencing technology. RESULTS: Of 16 RB cases, 13 showed LOH on chromosome 13. The frequency of LOH on 13q14 was about 75% (12/16), consistent with other reports. Investigation of parental origin of lost RB1 alleles showed that, in all these cases, the paternal alleles were preferentially lost. Aside from the RB1 locus, other regions with the frequency of LOH above 30% in these tumors were D13S265, D13S158, D13S170, D13S218, D13S285 and D13S159. In particular, the D13S265 locus at 13q31-32 showed the highest rate of allele loss (64%, 9/14 informative cases), suggesting the presence of 1 or several genes whose loss of function may contribute to the development of RB. Comparison of the genotypic characteristics of 3 sites of frequent LOH (D13S153, D13S263 and D13S265) with the clinicopathological phenotype, respectively, showed that LOH of each locus was preferentially associated with a significantly younger age at diagnosis of RB. CONCLUSIONS: LOH analysis at some specific loci on chromosome 13 may be of a value in RB patients as diagnostic markers.     

Human gastric adenocarcinoma allelotype on chromosomes 17 and 18

Allelic losses of multiple chromosome loci in gastric adenocarcinoma suggest that inactivation of tumour suppressor genes in these regions may be important for tumourigenesis. To define deletion intervals and find candidate tumour suppressor genes involved in gastric adenocarcinoma pathogenesis, a genome-wide search for loss of heterozygosity (LOH) was conducted in 45 patients with primary gastric adenocarcinoma. Investigations using 29 microsatellite markers spanning chromosomes 17 and 18 showed allelic deletion in 29 (64%) specimens at one or more loci. Five LOH overlap regions, three newly identified as deletion regions, were defined: RI, D17S831 - D17S921 at 17p12-13.3; RII, D17S1868 - D17S787 at 17q21.3-22; RIII, D17S785 - D17S928 at 17q25.3; RIV, D18S61 - D18S1161 at 18q22; and RV, D18S462 - D18S70 at 18q22-q23. Eleven (24%) patients with chromosome 17 allelic loss also showed LOH on 18q, with at least one region of overlapping. LOH mapping showed allelic losses were widespread on both chromosomes and suggests the possibility that multiple tumour suppressor genes, including one or more that are unknown, might be inactivated in the aetiology of gastric adenocarcinoma.