MECP2基因甲基化和羟甲基化水平的性别差异研究

目的 探讨MECP2在不同性别脑组织中是否有表达差异,从而与孤独症等疾病的性别差异相关。方法 利用4例非疾病流产胎儿脑标本,采用酚氯仿方法提取基因组DNA。在MethPrimer在线软件上检测MECP2基因-1 000 bp至+1 200 bp区间的CpG 岛。甲基化检测采用亚硫酸氢盐修饰后测序法（使用EZ DNA Methylation-goldTM Kit 试剂盒）。对于超声断裂后的基因组DNA,用基因组羟甲基化试剂盒（diagenode,hMeDIP kit）进行ChIP反应。反转录cDNA采用FastQuant RT Kit（With gDNase）试剂盒,定量PCR检测MECP2表达量采用 SuperReal PreMix Plus （SYBR Green）试剂盒。结果 标本1男,重量106 g,长度17.4 cm;标本2女,重量100 g,长度19.1 cm;标本3男,重量500 g,长度28.3 cm;标本4女,重量510 g,长度31.5 cm。MECP2表达量男性胚胎（标本1=0.0367,标本3=0.0155）高于女性胚胎（标本2=0.0177,标本4=0.0088）。MECP2的甲基化水平女性个体平均1条X染色体上MECP2的甲基化程度显著高于男性,特别是在启动子的核心区域-309 bp至-179 bp,男性MECP2上几乎没有甲基化,而羟甲基化水平男性高于女性。结论 男性MECP2基因的DNA修饰促进其表达,可能提高了男性胚胎对MECP2基因突变的易感性,从而影响MECP2基因突变导致的患病人群的性别差异。     

胆道闭锁患儿外周血T细胞ITGAL基因启动子区甲基化状态及其mRNA表达

目的 研究胆道闭锁（BA）患儿外周血T细胞ITGAL基因启动子区DNA甲基化状态及其对mRNA表达的影响。方法 选取2010年4~8月于复旦大学附属儿科医院（我院）初诊、并经外科手术病理学检查证实为BA的患儿为研究对象,分为BA组和甲基化结果验证组;选取我院同期行斜疝手术、日龄≤120 d和肝功能、肾功能正常的患儿为对照组。分离BA组和对照组CD4+和CD8+T细胞,提取DNA和RNA,行ITGAL基因启动子区DNA甲基化水平和mRNA表达水平检测。甲基化结果验证组分离细胞后,予5-氮杂胞苷干预和培养后,行甲基化水平和mRNA表达水平检测,验证研究结果。结果 BA组和对照组各20例进入研究,两组年龄和性别均匹配。①BA组和对照组CD4+和CD8+T细胞ITGAL基因启动子序列-250~250 bp均未发生甲基化。BA组CD4+T细胞-1450~-950 bp的CG二核苷酸平均甲基化水平显著高于CD8+T细胞（0.94 vs 0.75,P=0.02）,也显著高于对照组CD4+T细胞（0.94 vs 0.66,P<0.001）。②BA组外周血CD4+T细胞ITGAL mRNA表达显著低于CD8+T细胞（0.021±0.002 vs 0.032±0.004,P=0.013）,也显著低于对照组（0.021±0.002 vs 0.031±0.003,P=0.007）。BA组CD8+T细胞ITGAL mRNA表达与对照组差异无统计学意义（0.032±0.004 vs 0.034±0.006,P=0.266）。③甲基化验证组纳入5例BA患儿。验证结果显示,5-氮杂胞苷干预后CD4+和CD8+ T细胞ITGAL启动子区平均甲基化水平均显著低于未予5-氮杂胞苷干预的水平;ITGAL mRNA的表达均显著高于未予5-氮杂胞苷干预的水平。结论 BA患儿外周血CD4+ T细胞ITGAL启动子区发生高甲基化,并对mRNA表达产生影响。     

胰岛素样生长因子结合蛋白3在宫内生长受限儿中的甲基化研究

目的：探讨胰岛素样生长因子结合蛋白3（IGFBP3）启动子区甲基化状态在胎儿宫内生长受限（IUGR）中的作用。方法：选取IUGR新生儿50例及正常新生儿30例,应用甲基化特异性PCR（MSP）及高分辨率溶解（HRM）技术检测外周血中IGFBP3基因的甲基化状态。结果：IUGR组中IGFBP3启动子区完全甲基化比例为4%（2/50）,部分甲基化比例为40%（20/50）,未甲基化比例为56%（28/50）;对照组中部分甲基化比例为13%（4/30）,未甲基化比例为87%（26/30）,两组甲基化率差异有统计学意义(P＜0.01)。结论：IGFBP3基因启动子区的甲基化程度与IUGR的发生有关。     

血管瘤血管内皮生长因子受体KDR基因异常甲基化的研究

目的通过建立甲基化敏感性高分辨率溶解曲线法（MS-HRM）,检测血管内皮生长因子VEGF受体KDR基因启动子区域在不同时期血管瘤、血管畸形及正常皮肤组织中的甲基化状态,初步探讨基因甲基化在血管瘤形成、增生、退化过程中的作用。方法选取不同时期血管瘤石蜡标本48例、血管畸形石蜡标本15例、正常包皮皮肤组织标本8例,分别提取DNA,经亚硫酸氢盐甲基化修饰、纯化、回收DNA,然后用甲基化敏感性高分辨率溶解曲线法（MS-HRM）,定量检测不同标本中血管内皮生长因子受体KDR甲基化水平。结果48例血管瘤标本共检出32例不同程度KDR基因启动子区域甲基化（66．67％）,其中24例增殖期血管瘤标本中检出21例（87．50％）不同程度甲基化,24例消退期血管瘤标本中检出11例（45．83％）不同程度甲基化,增殖期血管瘤与消退期血管瘤标本中KDR的甲基化程度比较,差异有统计学意义（X^2=9．375,P〈0．05）;15例血管畸形标本中仅检出甲基化程度为0-25％者2例（13．33％）,8例正常包皮皮肤组织中检测到1例甲基化0-5％（12．50％）。与血管瘤相比,差异均有统计学意义（P〈0．05,Fisher’确切概率法）。结论血管瘤中血管内皮生长因子受体KDR基因启动子序列CpG岛存在异常甲基化,血管内皮生长因子受体KDR基因异常甲基化可能与血管瘤增生、退化等有关。     

T系和B系急性淋巴细胞白血病ID4甲基化状态分析

目的探讨DNA结合抑制因子4（ID4）基因甲基化与T系、B系及T/B双表达儿童急性淋巴细胞白血病（ALL）的关系。方法采用甲基化特异性聚合酶链式反应（MS-PCR）对18例初发ALL患儿进行ID4基因启动子区甲基化状况分析。18例ALL患儿中T系（T-ALL）2例,B系（B-ALL）13例,T/B双表达（T/B-ALL）3例。以34 例同期住院的非肿瘤性疾病患儿为对照组。结果ID4基因启动子区在初发ALL患儿中的完全甲基化率（15/18,83%）显著高于部分甲基化率（3/18,17％）,P＜0.05。T-ALL、B-ALL和T/B-ALL患儿的完全甲基化率分别为50%,85%,100%,显著高于对照组（18%;P0.05）。结论 ID4基因的甲基化可能与儿童ALL发病有关,T-ALL、B-ALL及T/B-ALL之间的ID4甲基化状态一致。［中国当代儿科杂志,2010,12(12)：940-942］     

肾母细胞瘤患儿p73基因的表达及其甲基化研究

目的：探讨肾母细胞瘤患儿血液中p73基因的转录表达、启动子甲基化状态及二者之间关系。方法：收集45例肾母细胞瘤患儿为病例组,以健康体检或因其他原因就诊的性别、年龄匹配的15例（排除肿瘤等恶性疾病）儿童为对照组。采集两组儿童外周血,运用实时荧光定量PCR（qRT-PCR）和甲基化特异性PCR (MSP)法检测p73基因转录表达水平及其启动子甲基化状态,并分析病例组中p73基因的表达及甲基化与临床资料的关系,及p73基因的甲基化对其转录表达的影响。结果：病例组中p73 mRNA的相对表达量（3.2±0.9）高于对照组（1.6±1.1）,差异有统计学意义（P<0.01）;病例组p73基因甲基化阳性率（20%）低于对照组 (73%),差异有统计学意义（P<0.01）。病例组中甲基化p73 mRNA的相对表达量大于非甲基化p73 mRNA的相对表达量（P<0.01）,且大于对照组中甲基化p73 mRNA的相对表达量（P<0.01）;非甲基化p73 mRNA的相对表达量在两组间差异无统计学意义（P=0.810）。结论：肾母细胞瘤外周血中p73基因启动子的异常甲基化是其基因表达调节方式之一,并与肾母细胞瘤的发生发展有关;发生甲基化的p73基因在肾母细胞瘤中有可能充当癌基因的角色,转录水平的过度表达与其甲基化状态有关。     

宫内发育迟缓大鼠肾脏Wilms瘤1基因DNA甲基化与蛋白尿关系

目的:观察宫内环境对肾脏Wilms瘤1（WT1）基因甲基化状态的影响及其与肾脏功能的关系,探讨宫内环境引发肾脏疾病的可能分子机制。方法:采用孕期全程低蛋白饮食法建立宫内发育迟缓（IUGR）大鼠模型,至自然分娩。对照组以孕期常规饲料饲养至自然分娩。12周龄时,比色法测定24 h尿蛋白定量,光镜下计数肾小球数目,实时PCR方法检测肾脏WT1基因mRNA水平及甲基转移酶DNMT1、DNMT3a和DNMT3b mRNA水平,MassARRAY定量分析检测WT1基因启动子区DNA甲基化状态。结果:①IUGR组新生鼠出生体重显著低于对照组（P<0.000 1）,直至12周龄时体重仍低于对照组（P=0.043）。②与对照组相比,12周龄时IUGR组大鼠24 h尿蛋白定量显著升高（P=0.016）;血清胱抑素C水平显著升高（P =0.036）,肾小球数目显著下降（P=0.001）。③与对照组相比,12周龄时IUGR组大鼠肾组织WT1基因mRNA的表达显著增高（P=0.047）,WT1基因启动子区甲基化水平显著降低（P=0.029）,并且其M1段甲基化水平与WT1基因mRNA的表达呈负相关（r=-0.939,P=0.000 1）,DNMT1和DNMT3b mRNA表达水平也显著下降（P值分别为0.003和0.010）。结论:不良的宫内环境可以影响大鼠肾脏WT1基因的甲基化状态,继而导致其异常表达,可能参与了IUGR大鼠成年期蛋白尿的发生。     

小儿肾母细胞瘤p16基因启动子区甲基化观察

目的：观察小儿肾母细胞瘤ｐ１６基因启动子区有无甲基化及有甲基化者与组织类型和预后之间关系。方法：２０例肾母细胞瘤（５例肾组织作对照）进行甲基化观察，使用三种内切酶分别为ＦｎｕＤⅡ、ＳａｃⅡ、ＨｐａⅡ。结果：肿瘤组有６例出现甲基化（对照组无甲基化），除１例属于预后良好型（ＦＨ）之外，余５例均属预后不良型（ＵＨ）。甲基化与组织类型有关。随访结果有甲基化病例（ＵＨ组），１例术后１．５年死亡，１例术后半年复发，证明甲基化影响着预后。结论：肾母细胞瘤ｐ１６基因启动子区存在甲基化，甲基化者属于组织预后不良类型者多。     

婴幼儿血管瘤survivin基因启动子甲基化的研究

目的 采用亚硫酸氢盐修饰后测序法(BSP)检测不同病理阶段的婴幼儿血管瘤组织及正常皮肤组织中survivin基因启动子区域CpG岛的甲基化状态,探讨survivin基因启动子甲基化与婴幼儿血管瘤增生与退化的可能关系.方法 ①采用免疫组化S-P法检测增殖期婴幼儿血管瘤石蜡标本30例、消退期30例及正常包皮皮肤组织标本10例中survivin蛋白的表达;②提取石蜡包埋块组织基因组DNA并纯化后,采用亚硫酸氢盐修饰后测序法(BSP)分别检测增殖期血管瘤30例、消退期血管瘤30例及正常包皮组织10例中survivin基因启动子CpG岛甲基化情况.结果 ①survivin 蛋白在增殖期血管瘤、消退期血管瘤和正常包皮组织中阳性表达率分别为76.6％ (23/30)、33.3％(10/30)和20.0％(2/10);②10例正常包皮皮肤组织中1例(10.0％)survivin基因启动子CpG岛非甲基化,9例(90.0％)甲基化;30例消退期血管瘤标本中8例(26.6％)survivin基因启动子CpG岛非甲基化,22例(73.3％)甲基化;30例增殖期血管瘤标本中24例(80.0％) survivin基因启动子CpG岛非甲基化,6例(20.0％)甲基化;增殖期血管瘤survivin基因启动子CpG岛甲基化率明显低于消退期和正常包皮组织;③survivin蛋白表达阳性的血管瘤33例中31例survivin基因启动子CpG岛为非甲基化,survivin蛋白表达阴性的27例中26例survivin基因启动子CpG岛为甲基化状态.结论 ①增殖期血管瘤survivin蛋白表达明显高于消退期血管瘤;②survivin基因启动子CpG岛甲基化状态在增殖期血管瘤、消退期血管瘤中存在明显差异;血管瘤组织中survivin基因启动子的甲基化状态与survivin蛋白的表达具有相关性;survivin基因启动子区CpG岛异常甲基化在血管瘤的增殖与消退调控中可能起到了一定作用.     

5,10-亚甲基四氢叶酸还原酶基因启动子区域甲基化状态与先天性心脏病的关系

目的通过比较先天性心脏病(CHD)患儿与无先天性出生缺陷儿童的5,10-亚甲基四氢叶酸还原酶(MTHFR)基因启动子区域甲基化状态,探讨MTHFR基因启动子甲基化状态与儿童CHD的关系。方法收集53例CHD患儿(病例组)及80例无先天性出生缺陷的儿童(对照组)外周静脉血液标本。二组儿童年龄为10个月～14岁,均为武汉市及周边地区的汉族人。病例组男29例,女24例;对照组男44例,女36例。首先提取血液白细胞DNA,然后对DNA进行亚硫酸氢钠修饰,采用甲基化特异性PCR(MSP)技术通过特异性引物检测MTHFR基因启动子区域甲基化状态。应用SPSS 15.0软件进行χ2检验,分析MTHFR基因启动子区域甲基化状态与CHD的关系。结果 MSP分析显示,病例组和对照组MTHFR基因启动子区域非甲基化分别为36例(67.92%)和69例(86.25%),部分甲基化分别为15例(28.30%)和9例(11.25%),甲基化分别为2例(3.78%)和2例(2.50%),2组间MTHFR基因启动子甲基化状态的差异具有统计学意义(χ2=6.554,P=0.038)。结论 MTHFR基因启动子区域超甲基化可能是导致CHD发病的原因之一。     

Lynch syndrome in a 15-year-old boy

Hereditary nonpolyposis colorectal cancer (HNPCC), or Lynch syndrome, dominantly inherited, is characterized by the development of a variety of cancers due to germline mutations in DNA mismatch repair genes (MMR). This syndrome was diagnosed in a 15-year-old boy because his father and grandmother were also found to have the same kind of cancer. Microsatellite instability prompted a search for germline mutations in the MLH1, MSH2, MSH6, and PMS2 genes. Use of immunohistochemical staining for MMR proteins, genomic sequencing, and deletion studies, evidenced MSH2 axonal deletion. Neoplastic lesions of colon are most often encountered in the adult population but can, on rare occasions, be found in younger patients. We would like to emphasize the importance of suspecting Lynch syndrome and performing genetic studies, even in young patients, when there is a familiy history of colorectal cancer.     

Anaplastic oligodendroglioma in an adolescent with Lynch syndrome

Lynch syndrome (hereditary non‐polyposis colorectal cancer; HNPCC) is an autosomal dominant cancer predisposition syndrome with high penetrance. It is caused by heterozygous germline mutations in one of the DNA mismatch repair (MMR) genes MLH1, MSH2, MSH6, and PMS2. Carriers are at high‐risk for developing colorectal carcinomas, as well as various extracolonic malignancies. This case report describes a 15 year‐old male with a confirmed germline mutation of MSH2 and early onset anaplastic oligodendroglioma. The patient's tumor showed loss of expression of MSH2 and MSH6 proteins with normal microsatellite stability. The immunohistochemical staining pattern provided strong evidence to support the inclusion of anaplastic oligodendroglioma as part of the spectrum of tumors found in Lynch syndrome. Pediatr Blood Cancer 2013; 60: E13–E15. © 2012 Wiley Periodicals, Inc.     

High-grade brain tumors in siblings with biallelic MSH6 mutations

Biallelic germline mutations of Constitutional mismatch repair-deficiency syndrome (CMMR-D) genes, MLH1, MSH2, MSH6, and PMS2 are characterized by increased risk of childhood malignancy. We report a case with CMMR-D caused by novel homozygous MSH6 mutations leading to gliomatosis cerebri and T-ALL in an 11-year-old female and glioblastoma multiforme in her 10-year-old brother, both with rapid progression of the diseases. A literature review on brain tumors in CMMR-D families shows that they are treatment-resistant and lead to early death. Identification of patients with CMMR-D is critical, and specific cancer screening programs with early surgery are recommended.     

Colorectal adenocarcinoma: a pediatric case review with a focus on mismatch repair gene mutations and E-cadherin expression

Colorectal adenocarcinoma (CRAC) is exceedingly rare in the pediatric population (fewer than 2 cases per 1 million children). There are 2 major categories of pediatric colorectal adenocarcinoma syndromes: polyposis-related and hereditary nonpolyposis colorectal cancer, also known as Lynch syndrome. Germ line mutations in DNA mismatch repair (MMR) genes (eg, MLH1, MSH2, PMS2, MSH6) have been established as the molecular genetic basis of Lynch syndrome. Another prognostic factor in adult CRAC is the reduced expression of epithelial cadherin (E-cadherin), which has been associated with poor outcome in some adult CRAC cases; however, its role in predicting prognoses in pediatric cases remains unclear. Seven pediatric patients with primary CRAC were reviewed. Available molecular genetic test results were evaluated, and immunohistochemical labeling for MMR proteins and E-cadherin were performed on 5 patients. Four of the 5 patients in our study with available paraffin blocks showed loss of MMR protein expression, consistent with Lynch syndrome. In cases stained for E-cadherin, 3 were strongly positive and 2 were weakly positive; however, with the small sample size and the relatively short follow-up period, an accurate correlation between E-cadherin and prognosis cannot be reached with any degree of certainty. Our findings highlight the importance of genetic testing for MMR gene mutations in children with colorectal cancer and suggest further investigation into the prognostic role of E-cadherin in pediatric CRAC.     

神经管缺陷的表观遗传学研究进展

本综述介绍了NTDs(神经管缺陷)的疾病特点,总结了目前国际及国内范围对该病的病因研究情况,综合近五年的对该病的表观遗传发病机制研究的文章,分别从DNA甲基化、组蛋白修饰、印迹基因、小分子核糖核酸等表观遗传修饰在NTDs病因中的作用进行了详细的描述,并从NTDs发病的相关信号通路入手,总结了不同信号通路中基因组DNA甲基化与NTDs发生的关系.     

No evidence for additional imprinting defects in Silver-Russell syndrome patients with maternal uniparental disomy 7 or 11p15 epimutation

Silver-Russell syndrome (SRS) is mainly characterised by intrauterine and postnatal growth retardation (IUGR and PNGR), asymmetry, clinodactyly V and craniofacial abnormalities. More than 35% of patients carry a hypomethylation of the telomeric imprinting centre region 1 (ICR1) in 11p15; single patients show a maternal duplication of 11p15. An additional 7-10% of patients with SRS have maternal uniparental disomy of chromosome 7 (mUPD7). Another disorder caused by epigenetic defects is transient neonatal diabetes mellitus (TNDM) which is associated with loss of methylation (LOM) in 6q24. After detecting methylation loss at multiple imprinted loci in patients with TNDM, Mackay et al. recently proposed the existence of a maternal hypomethylation syndrome presenting as TNDM. They therefore concluded that patients with other disorders associated with LOM at one (maternally) methylated locus might also carry LOM at multiple loci. Similar observations have also been reported in Beckwith-Wiedemann syndrome (BWS): nearly 25% of patients displayed abnormal methylation patterns of ICRs additional to those in 11p15. To show whether general hypomethylation is a common phenomenon in imprinting disorders we carried out methylation analyses for the imprinted regions 14q32, 6q24 and the centromeric imprinting region ICR2 on 11p15 for 10 patients with SRS carrying mUPD7 and 22 patients with LOM at the telomeric imprinting region ICR1. We showed that further epigenetic defects did not occur in the groups of SRS with LOM of ICR1 or mUPD7, and that these subentities do not belong to the diseases with a general hypomethylation defect, such as TNDM and BWS.     

O6-methylguanine-DNA methyltransferase activity and promoter methylation status in pediatric rhabdomyosarcoma

OBJECTIVES: To determine the activity of the DNA repair protein O6-methylguanine-DNA methyltransferase (MGMT) and MGMT promoter methylation status of pediatric rhabdomyosarcoma (RMS) and examine MGMT in RMS tumors from different prognostic groups. METHODS: Fifteen samples each of the alveolar (ARMS) and embryonal (ERMS) subtypes were obtained for analysis of MGMT activity and promoter methylation status. MGMT activity was assayed by measuring the removal of O6-[3H] methylguanine from [3H]-methylated substrate by a tumor extract containing the enzyme. Promoter methylation status was examined using methylation-specific polymerase chain reaction (PCR). RESULTS: MGMT activity was successfully assayed from 25 samples, 10 ERMS and 15 ARMS. All ERMS and 11 of the 15 ARMS samples displayed high activity levels. There was significant intertumor variability among both subtypes but no significant difference in mean activity between the two histologic groups. There were trends toward increased activity in ERMS tumors and tumors from anatomically unfavorable locations. Only one tumor was hypermethylated at the MGMT promoter region. CONCLUSIONS: This analysis suggests that a low percentage of RMS samples are hypermethylated at the MGMT promoter and that most have significant MGMT activity, implying that clinical trials with MGMT-modulating agents may have a role in the treatment of these tumors. This analysis does not support MGMT activity as an explanation of the differential response to chemotherapy demonstrated by ARMS and ERMS, but does suggest that MGMT may be involved in RMS treatment failure regardless of subtype and in the poorer response shown by tumors from unfavorable locations.     

Upstream CpG island methylation of the PAX3 gene in human rhabdomyosarcomas

BACKGROUND: Adult tumors can be characterized by hypermethylation of CpG islands associated with 5'-upstream and coding regions of specific genes. This hypermethylation can also be part of the aging process. In contrast, much less is known about gene hypermethylation in childhood cancers, where methylation changes are not part of the aging process but likely represent developmental dysregulation. PAX3 is an important gene in muscle development and muscle-producing neoplasms such as rhabdomyosarcomas. PROCEDURES: We examined the methylation status of a PAX3 5'-CpG island in rhabdomyosarcoma subtypes and in normal fetal skeletal muscle. PAX3 methylation was analyzed in 15 embryonal rhabdomyosarcomas, 12 alveolar rhabdomyosarcomas, and in six normal skeletal muscle samples, using semi-quantitative PCR analysis of DNA digested with methyl-sensitive restriction enzymes. RESULTS: The CpG island in the upstream region of the human PAX3 gene was hypermethylated in the majority of ERMS examined (13 of 15 tumors, mean of 52% methylation), whereas most ARMS (9 of 12 tumors) and all normal muscle samples showed relative hypomethylation (both 18% mean methylation). Various CpG sites differ in contribution to overall PAX3 CpG island methylation, with methylation at a HaeII site being inversely correlated with PAX3 expression. CONCLUSIONS: PAX3 CpG island methylation appears to distinguish embryonal subtype of rhabdomyosarcoma from alveolar, and methylation at certain sites within this CpG island is inversely correlated with PAX3 expression. In addition to exemplifying developmental dysregulation, methylation of PAX3 has potential in the development of an epigenetic profile for the diagnosis of rhabdomyosarcoma.     

MGMT promoter methylation correlates with survival benefit and sensitivity to temozolomide in pediatric glioblastoma

BACKGROUND: Methylation of the DNA-repair gene O6-methylguanine-DNA methyltransferase (MGMT) causes gene silencing. This epigenetic modification has been associated with a favorable prognosis in adult patients with glioblastoma (GBM) who receive temozolomide and other alkylating agents. We explored MGMT promoter methylation in pediatric GBM and its relationship to survival and temozolomide sensitivity. PROCEDURE: We performed a retrospective study of MGMT promoter methylation in 10 pediatric GBM. The methylation status of the MGMT was determined using a 2-stage methylation specific PCR analysis on DNA extracted from tumor specimens which had been snap frozen at surgery. The relationships between MGMT promoter methylation and patient outcome and response to temozolomide were evaluated. RESULTS: Four of our 10 pediatric patients with GBM were found to have methylation of the MGMT gene promoter. Methylation of the MGMT promoter was shown to correlate (P = 0.0005) with survival. The average survival time for patients with methyltated MGMT was 13.7 months as compared to 2.5 months for the 6 patients with unmethylated MGMT promoter. Of the seven patients that received temozolomide, those patients that had the methylated MGMT gene promoter responded better to treatment (P = 0.007). CONCLUSIONS: As in adults, pediatric GBM patients with methylated MGMT promoter benefited from temozolomide. However, a stronger correlation with overall survival, regardless of treatment, was observed in this group of patients. These data suggest that MGMT methylation may be a prognostic factor for survival in pediatric GBM, as well as a marker for temozolomide sensitivity.