散发性结直肠癌22q13区域杂合缺失的精细定位分析

目的在染色体高频杂合缺失区22q13精细定位，以筛查可能与结直肠癌相关的肿瘤抑制基因。方法荧光标记的微卫星引物与83例结直肠癌的肿瘤和正常组织进行PCR反应。产物在ABI Prism 377自动荧光测序仪进行电泳、扫描以及杂合缺失分析。其结果与临床病理因素进行相关性检验。结果8个位点平均杂合缺失率为35．6％。发现两个高频缺失区域：一个在D22S1171和D22S274之间，约2．7厘摩（cM）；另一个在D22S1160和D22S1149位点之间，约1．8cM。D22S1171位点与肿瘤发生部位显著相关（P=0．020）；D22S114位点与肝转移显著相关（P=0．008）；D22S1160位点与淋巴结转移显著相关（P=0．016）；其余位点与临床病理因素无显著相关性（P〉0．05）。筛选发现ARHGAP8基因和PPARA基因可能是肿瘤抑制基因。结论散发性结直肠癌22q13区域存在两个高频杂合缺失区，分别约2．7cM及1．8cM。ARHGAP8基因和PPARA基因可能是22q13区域与散发性结直肠癌相关的肿瘤抑制基因。     

散发性结直肠癌4号染色体等位基因杂合缺失的研究

目的 通过在4号染色体寻找杂合缺失区域，为定位、筛选高频杂合缺失区存在的散发性结直肠癌相关肿瘤抑制基因提供依据。方法 20个荧光标记的微卫星引物与83例结、直肠癌的肿瘤和正常组织进行聚合酶链反应。微卫星的平均遗传距离是10．4里摩（cm01）。产物进行电泳、扫描及杂合缺失分析，并与临床、病理因素进行相关性检验。结果 短臂（4p）、长臂（4q）的平均杂合缺失率为24．25％、28．56％，可见3个最小的高频缺失区域（Region）：R1：在D4S405和D4s3013（4p14—15．2）之间；R2：在D4s3000和D4s2915位点之间（4q12—21．1）；R3：在D4S407和IMS2939位点之间（4q25—31．1）。D4S1534位点与肝脏转移有关（P〈0．05），其余位点与临床病理因素均无显著相关（P〉0．05）。结论 4号染色体的3个高频杂合缺失区域4p14—15．2、4q12—21．1、4q25—31．1存在散发性结直肠癌发生、发展相关的肿瘤抑制基因。     

散发性结直肠癌染色体4p15等位基因杂合缺失的精细定位研究

目的通过在染色体4p15精细定位高频杂合缺失区域的范围．为筛选高频杂合缺失区内存在的散发性结直肠癌相关肿瘤抑制基因提供依据。方法7个荧光标记的微卫星引物与83例散发性结直肠癌的肿瘤和正常组织进行聚合酶链反应。微卫星之间的的平均遗传距离是1．02cM（centi—Morgon，里摩）。产物进行电泳、扫描及杂合缺失分析，并与临床、病理因素进行相关性检验。结果染色体4p15的平均杂合缺失率为21，34％，最高的是D4S3103位点（35．62％）；最低的是D4S2933位点（12．50％）。可能的肿瘤抑制基因的范围在D4S3017-D4S2933之间约1．7cM的遗传距离内，该区域内有PPARGC1A和GBA3两个基因。D4S1546位点杂合缺失与肿瘤直径显著相关（P〈0．05），其余位点与临床病理因索均无显著相关（P〉0．05）。结论染色体4p15精细定位后高频杂合缺失区域的范围限定在D4S3017-D4S2933之间约1．7cM的范围内。该区域内PPARGC1A和GBA3两个基因可能是散发性结直肠癌相关的肿瘤抑制基因。     

散发性结直肠癌患者18号染色体高频杂合缺失的研究

目的：探讨散发性结直肠癌患者18号染色体上抑癌基因相关的杂合缺失（LOH）情况，并探索新的抑癌基因位点。方法：对83例散发性结直肠癌患者基因组DNA用14个不同荧光标记的高度多态性微卫生引物，扩增相应的微卫星位点，平均距离为10厘摩（centi-morgan,cM）。用ABI PRISM377测序仪进行基因扫描，统计各位点杂合缺失率。结果：在12个获得有效数据的微卫星位点中，平均杂合缺失率为36．78％,18p中最高为D18S53（38．09％），18q中最高为D18S474（55．74％）。4位患者的18号染色体所有杂合位点都存在缺失，30位患者的杂合缺失位点不少于50％（平均6个／人）；缺失位点少于50％的有53人（平均1个／人）。结论：结直肠癌患者18号染色体存在高频的LOH，并以整体缺失为特点。存在高频LOH的区域定位有转化生长因子（TGF）信号传导相关基因、结直肠癌缺失基因（DCC）、Rb结合蛋白8(RbBP8），特别是TGF信号传导相关基因MADH2、4、转化生长因子－β1反应元件（TGF－β1）等的缺失可能对结直肠癌的发生有重要影响。18p也有存在未知抑癌基因的可能。     

散发性结直肠癌1号染色体等位基因杂合缺失精细定位研究

目的抑癌基因的杂合缺失（LOH）被认为是结直肠癌形成的通路之一。本实验通过对1号染色体1p36．33～36．31、1q31．1～32、1区域进行杂合缺失精细定位分析，以发现更精确的高频杂合缺失区域。方法在1p36．33～36．31、1q31．1～32．1区域分别选择7个、6个荧光标记微卫星引物与83例结直肠癌的肿瘤和正常组织进行聚合酶链反应（PCR）反应。产物在电泳后进行LOH分析。LOH结果与临床病理参数之间的关系比较采用X^2检验。结果1p36．33～36．31区域平均杂合缺失率是31．47％，以D1S243位点最高，为47．22％（34／72），最低是D1S1347，为7．35％（5／68）。存在两个高频杂合缺失区域：D1S243位点（1p36．33）以及D1S468-D1S2660区域（1p36．32～36．31）。1q31．1～32．1区域平均杂合缺失率是22．98％，以D1S2622位点最高，为36．73％（18／49），最低是D1S412，为16．42％（11／67）。更精确的缺失范围定位在D1S413和D1S2622之间（1q31．3—32．1），大约2cm的遗传距离范围内。1p36．33～36．31、1q31．1～32．1区域各位点的杂合缺失率与性别、年龄、肿瘤大小、生长方式以及Dukes分期无显著相关。提示该区域上的杂合缺失现象普遍存在于各种类型的散发性结直肠癌中。结论1号染色体上存在3个高频杂合缺失区域，D1S243位点（1cm）、D1S468和D1S2660位点之间（3cm）以及D1S413和D1S2622之间（2cm），提示在这些区域存在与结直肠癌相关的抑癌基因。     

胃癌染色体1q43区域等位基因杂合缺失精细定位研究

目的 对胃癌1号染色体1q43区域的微卫星位点进行杂合缺失(LOH)研究,为筛选此区域内可能存在的胃癌相关抑癌基因提供依据.方法 4对荧光标记的微卫星引物(D1S1594、D1S2785、D1S304、D1S321)覆盖1q43区域与96例胃癌患者的肿瘤组织及正常组织进行多重聚合酶链反应(PCR).产物经毛细管电泳后进行LOH分析.结果 该区域所测位点平均杂合缺失率17.9%,其中D1S1594位点最高,杂合缺失率为26.5%;D1S2785位点杂合缺失率最低为7.7%.1q43区域各位点的杂合缺失率与性别、年龄、肿瘤大小及TNM分期无明显相关.结论 在1q43区域内发现一个高频LOH区域,即D1S1594及D1S2785位点之间约1 cm区域,提示该区域内存在与胃癌相关的抑癌基因.     

散发性结直肠癌染色体7q21-22区杂合性缺失精细定位

目的 研究散发性结直肠癌7号染色体杂合性缺失,对7q21-22区精细定位,寻找新的结直肠癌抑癌基因.方法 采用15对微卫星DNA标记7号染色体,在高频杂合缺失区另取5对微卫星标记对83例结直肠癌病例的肿瘤和正常组织进行PCR反应.PCR产物在ABI Prism 377自动荧光测序仪进行电泳3 h,以GeneScan3.1和Genotyper 2.1软件进行基因分型.结果 在7号染色体上发现1个高频杂合缺失区即7q21-22区.对该区再用5对微卫星标记引物行精细定位,界定了1个跨越D7S657、D7S646位点精细的高频杂合缺失区域.结论 通过精细杂合缺失作图的研究,在7号染色体发现了1个跨越D7S657、D7S646位点的精细杂合缺失区,该区很可能存在1个或多个与结直肠癌相关的新的抑癌基因.     

散发性结直肠癌微卫星不稳定性与Mt-p53及bcl-2蛋白表达的研究

目的 探讨散发性结直肠癌微卫星不稳定性民Mt-p53及bcl-2蛋白表达的关系。方法 应用聚合酶链式反应（PCR）技术检测了48例散发性结白肠癌中四个位点的微卫星不稳定性,同时应用免疫组织化学技术对癌基因bcl-2、抑癌基因Mt-p53蛋白的表达。结果 ①48例散发性结直肠癌中四个微卫星位点D2S123、BAT-26、D17S261、D16S799的微卫垦不稳定性检出率分别为12.5％、18.8％、10.4％、8.3％;②Mt-p53蛋白和bcl-2蛋白阳性个分别为66.7％和77.1％;③微卫星不稳定性与mt-p53和bcl-2蛋白的表达均相差个显著（P>0.05）。结论 微卫星不稳定性引起散发性结直肠癌的RER途径是不同于由抑癌基因p53失活及癌基因bcl-2的激活引起的LOH途径的新致癌机制。     

散发性胆管癌患者染色体3p21.3区段微卫星位点不稳定性分析

目的研究散发性胆管癌患者染色体3p21．3区段的微卫星不稳定性（MSI）及杂合性缺失（LOH），探讨染色体3p21．3区段遗传不稳定性与散发性胆管癌发生发展的关系，定位该区段上散发性胆管癌相关肿瘤基因。方法用聚合酶链反应一单链构象多态性分析（PCR—SSCP）方法检测24例散发性胆管癌患者染色体3p21．3区段上D3S1568、D3S1621、D3S1578和D3S1289四个微卫星位点的MSI和LOH发生率，分析其与临床病理因素之间的关系。结果24例散发性胆管癌组织中，4个微卫星位点的MSI和LOH平均发生率分别为7．23％和15．63％。其中D3S1621位点的LOH最高（45．83％，11／24），并与TNM分期、是否伴有局部／淋巴结转移相关（P〈0．05）。结论染色体3p21．3区段133S1621位点高频率杂合性缺失，提示3p21．3区段定位有散发性胆管癌的候选抑癌基因，并在散发性胆管癌的发生发展过程中发挥重要作用。     

散发性结直肠癌微卫星不稳定与hMHL1和hMSH2基因突变的研究

目的:探讨散发结直肠癌组织微卫星不稳定性与错配修复基因hMHL1和hMSH2蛋白表达的关系。方法:结直肠癌患者病理标本和正常肠壁组织(距肿瘤边缘10cm取材各40例)。选取微卫星位点(D2S123、BAT-26、D17S261、D17S799)进行PCR,PCR产物行毛细管电泳法检测。用免疫组化染色方法分析错配修复基因hMHL1和hMSH2在肿瘤组织的蛋白表达情况。结果:1)4个位点(D2S123、BAT26、D17S261、D17S799)的微卫星不稳定性检出率分别为:12.5%、17.5%、10%、7.5%。总的微卫星不稳定率为9/40(22.5%)。MSI-H表达为7例,均表现BAT26位点不稳定。MSI-L表达2例。2)所有标本错配修复基因hMSH2检测均正常表达。错配修复基因hMHL1表达阴性11份,结肠比直肠hMLH1蛋白的阴性表达率高(P0.01)。3)hMLH1表达阴性,是出现MSI的重要分子因素,hMLH1不表达和MSI相关显著(P0.01)。结论:1)错配修复基因突变引起微卫星不稳定性是散发性结肠癌发生的重要机制;2)部分微卫星不稳定性是由错配修复基因hMLH1不表达引起,其余的微卫星不稳定性可能涉及到其它错配修复基因。     

Comprehensive loss of heterozygosity analysis and identification of a novel hotspot at 3p21 in salivary gland neoplasms.

OBJECTIVES: We sought to assess loss of heterozygosity (LOH) profiles of 3p, 6q, 8q, 10q, 12q, 13q, and 17p and to identify the tumor suppressor genes involved in salivary gland neoplasms. STUDY DESIGN: LOH analysis was performed using 26 microsatellite markers by polymerase chain reaction-polyacrylamide gel electrophoresis method in 20 benign and 6 malignant salivary gland tumors. RESULTS: Overall, LOH was detected in at least one informative locus in 18 of 20 (90%) of benign tumors and in all of 6 cases of malignant tumors. High LOH frequencies were revealed at the loci D3S1307 (22%, 3p26), D3S966 (41%, 3p21), D6S255 (27%, 6q25), D8S166 (25%, 8q12), D8S199 (21%, 8q24), and D10S1765 (28%, 10q23) in benign tumors, defining the hotspot regions for putative tumor suppressor genes. CONCLUSIONS AND SIGNIFICANCE: The hotspot regions defined by the present study suggest that new tumor suppressor genes related to the development of salivary gland tumors may reside at several chromosomal loci, including loci at 3p, 6q, 8q and 10q.     

膀胱移行细胞癌9q的杂合性丢失及抑癌基因位点的定位

目的研究膀胱移行细胞癌的９号染色体长臂（９ｑ）杂合性丢失并对抑癌基因位点进行定位。方法通过应用２５对高密度多态性微小卫星标记经ＰＣＲ扩增，６％变性聚丙烯酰胺凝胶电泳，检测膀胱移行细胞癌的９ｑ杂合性丢失，寻找膀胱移行细胞癌相关抑癌基因的位点。结果２５例病人约有９２％的肿瘤至少有一个以上位点的杂合性丢失，最常见的丢失区域为９ｑ１２～９ｑ２１、９ｑ２２和９ｑ３４，最常见的丢失位点是ＤＢＨ４４．０％、Ｄ９Ｓ１５２２７％、Ｄ９Ｓ１８１５２２７％、Ｄ９Ｓ１７６１２．０％、Ｄ９Ｓ１８３１１６．０％。绘制出膀胱移行细胞癌９ｑ杂合性丢失的染色体图谱，９ｑ杂合性丢失与肿瘤的分级、分期无相关性。结论膀胱移行细胞癌９ｑ的杂合性丢失是肿瘤发生的早期事件之一，在９ｑ３４的ＤＢＨ位点及其附近可能有与膀胱肿瘤相关的抑癌基因存在，并与肿瘤的发生有关。     

Loss of heterozygosity analysis identifies genetic abnormalities in mycosis fungoides and specific loci associated with disease progression

Mycosis fungoides (MF) exhibits a variety of underlying molecular defects. Loss of heterozygosity (LOH) is a technique used to detect chromosomal imbalances in neoplastic disorders using archival tissue. We analyzed skin biopsies of MF in different stages for the presence of LOH at specific loci to evaluate underlying genetic aberrations involved in MF and its progression. Twenty-five skin biopsies (15 plaque stage and 10 tumor stage) from 19 patients were evaluated. LOH was examined at 1p22 (D1S2766), 9p21 [IFNA, p15 (D9S1748), p16 (D9S171)], 10q23 [PTEN (D10S185, D10S541, D10S2491)], and 17p13 [p53 (TP53)]. Abnormal lymphocytes were microdissected from formalin-fixed, paraffin-embedded tissue sections. Sixteen of the 25 (64%) specimens evaluated had at least one abnormal LOH locus and LOH was identified in 7 of 15 (47%) plaque and in 9 of 10 (90%) tumor stage lesions, respectively. All 3 patients with sequential biopsies (plaque followed by tumor lesions) had additional LOH abnormalities in tumor specimens compared with plaque stage lesions. LOH most frequently involved chromosome 10, including 7 of 10 (70%) tumor stage lesions. Loss of multiple alleles was only identified in tumor stage cases, with 3 tumors undergoing allelic losses at 3 separate loci. Our results suggest that LOH studies are a robust method for evaluating genetic abnormalities in MF. Tumor stage lesions manifest increasing allelic losses compared with plaque stage. Further, in this series, several loci associated with the tumor suppressor gene PTEN on chromosome 10 appear to be associated with progression from plaque to tumor stage.     

应用激光捕获显微切割技术对肝细胞癌8号染色体短臂杂合性缺失的研究

目的探讨8p杂合性缺失（LOH）的特点及其与肝细胞癌（HCC）临床病理特征的相关性。方法选择8p上5个具有高度多态性的微卫星标记，对62例HCC组织利用激光捕获显微切割（LCM）技术进行LOH分析。结果有56．5％（35／62）的HCC患者在1个或多个基因位点发生LOH。LOH频率最高的3个位点依次为D8S298（51．1％，24／47）、D8S1771（48．8％，21／43）和D8S264（43．5％，20／46）。D8S298位点肝内转移者的LOH频率明显高于无转移者（P〈0．05）；在D8S1771位点，肿瘤直径〉3cm的LOH频率明显高于≤3cm组（P〈0．05）。结论HCC在染色体8p特定位点上LOH明显，在这些区域可能存在一个或多个与HCC发生发展相关的肿瘤抑制基因。8p上部分位点的LOH与临床病理特征有一定的相关性。     

Frequently deleted loci on chromosome 9 may harbor several tumor suppressor genes in human renal cell carcinoma

PURPOSE: Loss of various loci on chromosome 9 has been reported in various cancers. To determine the frequency of deletions at different loci of chromosome 9 in renal cell carcinoma microdissected samples of normal renal epithelium and carcinoma from the same patients were analyzed. MATERIALS AND METHODS: DNA was isolated from microdissected sections of normal and tumor cells of 60 renal specimens, amplified by polymerase chain reaction and analyzed for loss of heterozygosity on chromosome 9 using the 16 microsatellite markers D9S178, D9S157, D9S274, D9S168, D9S285, D9S156, D9S1839, D9S162, IFNA, D9S736, D9S171, D9S1749, D9S273D9S270, D9S153 and D9S170. Loss of heterozygosity was analyzed by a polymerase chain reaction based technique developed at our laboratory. RESULTS: This study showed a high incidence of loss of heterozygosity on chromosome 9 in renal cell carcinoma. Of 60 cases 44 (73%), 24 (40%) and 14 (23%) showed loss of heterozygosity at a minimum of 1, at a minimum of 3 and at 4 or more loci, respectively. The main deletion was found on the 9p21 region at loci DS171 in 38% of cases, D9S1749 in 42% and DS270 in 14%. Overall deletion on chromosome 9p21 was noted in 57% of renal cancer cases. Other deleted regions were on chromosome 9p'0022 to 23 at loci D9S157 in 37% of cases, D9S274 in 20%, D9S168 in 27%, D9S285 in 20%, D9S156 in 12%, D9S1839 in 17% and D9S162 in 24%. Overall deletion at chromosome 9q32 to 33 was noted in 46% of renal cell carcinoma cases. Chromosome 9q32 to 33 also showed deletion at locus D9S170 in 22% of renal cell carcinoma cases. When we compared the incidence of deletion at various loci on chromosome 9 according to renal cell carcinoma grade, we found a higher rate of deletion in advanced grades of renal cell carcinoma. A candidate target tumor suppressor gene, p16 (MTS-1/CDKN2), has been identified within the 9p21 deleted region in various cancers. In our study the expression of p16 protein was absent or low in renal cell cancer samples, suggesting that loss of the p16 gene may be involved in renal cell carcinogenesis. CONCLUSIONS: Our study demonstrates a high incidence of loss of heterozygosity on chromosome 9, mainly 9p21 and 9p22 to 23, in renal cell carcinoma, suggesting several putative tumor suppressor genes on these regions. The identification of other tumor suppressor genes on the 9p21 and 9p22 to 23 regions warrants further studies.     

染色体杂合性缺失在肝细胞癌根治术后预后预测中的价值

目的 通过生存分析探讨染色体杂合性缺失(LOH)在肝细胞癌(HCC)患者根治术后预后预测中的价值.方法 选取1 p、8p、17p、4q、13q及16q共6条染色体上24个具有高度多态性的微卫星标记,对1999年1月至2000年5月225例行根治术的HCC石蜡标本应用微切割技术,获取纯净肿瘤DNA进行LOH检测,并分析LOH与HCC患者根治术后5年总体生存(OS)、无瘤生存(DFS)的关系.结果 LOH在检测的染色体位点上发生明显.在单因素分析中,D8S298位点LOH的患者根治术后5年OS、DFS率皆明显低于无LOH的患者[(39±6)比(54±5),P＜0.05;(36±7)比(60±6),P＜0.01].同样,在D1S199基因位点,LOH患者术后5年OS、DFS率亦显著低于无LOH者[(28±7)比(55±5),P＜0.01;(29±8)比(53±5),P＜0.05].在其他22个检测位点,未发现LOH与HCC术后生存相关.在多因素分析中,Cox比例风险模型显示D8S298、D1S199位点LOH分别是HCC患者根治术后DFS、OS较差的独立因素(P均＜0.05).结论 D8S298、D1S199位点LOH有可能分别成为HCC患者根治术后预测转移复发及总体生存的分子标记.     

Genetic changes in uroepithelial tumors of patients with Balkan endemic nephropathy

BACKGROUND: Balkan endemic nephropathy (BEN) is seen in certain regions of the Balkan Peninsula. The patients are predisposed to epithelial cell tumors of the urinary tract. These tumors have not been genetically investigated so far. METHODS: We studied the loss of heterozygosity (LOH) in three BEN-associated tumors at seven microsatellite loci at 3q21.3 - 3q27.3. Comparative genomic hybridization (CGH) was also done and one of the tumors was investigated by 24-color FISH as well. RESULTS: LOH in locus D3S1299 (3q24) was established in one case. CGH showed genetic gains at 1q, 3q, 7p, 7q, 15q, and 19q in at least two of the three tumors. Genetic loss was found in one case at 4q. Most frequent aberrations detected by 24-color FISH were der(X), der(X)t(X;18), der(16), der(3)t(3;15) and der(12). CONCLUSION: The LOH suggests the presence of a new, so far unidentified tumor-suppressor gene at 3q24. In pTa BEN tumor CGH showed genome instability was extremely high. The 24-color FISH indicated highly complex chromosomal rearrangements. Chromosome 3 anomalies support our previous data on 3q24 - 3q26.3 association with BEN.     

Loss of heterozygosity at 7q31.1 and 12p13-12 in advanced prostate cancer

BACKGROUND: Allelic losses on chromosome arms 2q, 3p, 5q, 6q, 7q, 8p, 9p, 10p, 10q, 11p, 11q, 12p, 13q, 16q, 17p, 17q, 18q, and 21q are reportedly associated with progression and/or initiation of prostate cancer. In the present study, we performed a polymerase chain reaction (PCR) analysis of polymorphic microsatellite loci on the human chromosomes 7 and 12p13-12 in prostate cancer tissue to investigate the extent of involvement of these regions, which may contain putative tumor suppressor genes. METHODS: Tissue samples were obtained at autopsy from 17 men who died of hormone-refractory prostate cancer at Chiba University, Japan, and affiliated hospitals between June of 1992 and June of 1995. DNA from normal tumor or metastatic tissue was used as the template for PCR amplification of a set of 16 polymorphic microsatellite loci on human chromosome 7 and 6 loci on the human chromosome region 12p13-12. RESULTS: The frequencies of cases with loss of heterozygosity (LOH) at 7q31.1 were 8% in primary tumor tissue and 11% in metastatic tissue. The frequencies of cases with LOH at 12p13-12 were 12% in primary tumor tissue and 25% in metastatic tumor tissue. CONCLUSIONS: In the present study, the frequencies of LOH at 7q31.1 were lower than in Western patients, suggesting that LOH in this region is not related to progression of prostate cancer in Japanese patients. The frequency of LOH at 12p13-12 was similar to that reported in Western countries, indicating that 12p13-12 may contain a tumor suppressor gene of prostate cancer.     

肾源性剩余与肾母细胞瘤发生的关系

目的 探讨肾源性剩余与肾母细胞瘤多步骤发生在形态学和遗传学上的关系。方法 采用显微切割技术对13例伴有肾源性剩余的肾母细胞瘤石蜡切片，在llpl3，llpl5和16q位点设计引物行PCR扩增，观察杂合性丢失(LOH)发生阶段及其相关的潜在抑癌基因。结果 在llpl3位点检测到2例LOH，在llpl5位点检测到3例LOH，两位点同时发生LOH 1例。肾源性剩余llp能检测出LOH者，其对应的肿瘤中均能检测出LOH。16q位点在肾源性剩余内均未见LOH，而在肿瘤内检测出LOH2例，该2例出现肿瘤复发或转移。结论 在遗传学上进一步证明肾源性剩余是癌前病变，在肾母细胞瘤发病机理中llpl3和llpl5 LOH为早期因素，16q LOH发生较晚，证实肾母细胞瘤发病的多阶段模型。