ID4基因甲基化定量PCR检测在急性白血病中的临床意义

尽管治疗的进步极大地改善了急性白血病患者的预后和生存，但时至今日多数类型的急性白血病没有特异性的生物标记，因此对于多数白血病患者，影响生存的复发这一重要因素缺少有效的预警机制。删基因启动子区甲基化广泛发生于各类型急性白血病。本研究在前期建立的甲基化定量PCR体系的基础上，用该方法检测患者骨髓样本，探讨ID4甲基化定量指标（percentageofmethylatedreference，PMR）的临床意义。采集我院门诊及住院确诊的初治、完全缓解、复发3个阶段的急性白血病患者骨髓样本及正常对照者骨髓样本。应用ID4甲基化定量PCR体系对样本进行检测。按初治、完全缓解、复发分组比较PMR值。比较相同病例不同疾病状态的PMR的动态变化。结果表明，初治组PMR最高，其次为复发组，而完全缓解组最低。初治组PMR与完全缓解组比较存在统计学差异。4例随访病例的PMR值波动与病情变化一致。在1例复发病例中，PMR升高早于骨髓细胞学检查确认复发1．7个月。结论：本研究通过1／94基因启动子区甲基定量检测的方法初步验证：甲基化水平的量化指标PMR值与急性白血病患者肿瘤细胞负荷关系密切。PMR动态监测波动与疾病变化一致，可能具有预测复发的作用，但IIM甲基化定量指标的临床价值还有待进一步研究证据的支持。

Clinical Significance of ID4 Methylation Detection by Quantitative Methylation-Specific PCR in Acute Leukemia

The advances of treatment improved the prognosis of the patients with acute leukemia （AL） in the last decade, but the lack of general biomarker for predicting relapse in AL, which is one of the most important factors influ- encing the survival and prognosis. DNA methylation of ID4 gene promoter occurred frequently in patients with AL and was found to be highly related to the tumor progression. Based on the previous work of the setup of methylation-specific quantitative PCR system for ID4 gene, this study was designed to investigate the relation between the quantitative indicator of methylation density, percentage of methylation reference（PMR） value, and different disease status of AL. PMR of ID4 was detected by MS-PCR in bone marrow （BM） samples of 17 healthy persons and 54 AL patients in the status of newy diagnosis, complete remission and disease relapse. The results showed that at different disease status, PMR val- ue in newly diagnosed group was significantly lower than that in complete remission group （P = 0. 031 ）. Among serial samples, PMR value remained very low at the status of patients with continuous complete remission （ 〈 1.5%0）, and increased along with the accumulation of tumor cells at relapse. In 1 relapse case, the abnormal rise of PMR value occurred prior to morphological relapse. PMR value seemed to be related to body tumor cell load. It is concluded that the quantitative indicator of methylation density and PMR value may reflect the change of tumor cell load in acute leukemia patients. Dynamic monitoring of PMR maybe predict leukemia relapse.