Detection of malignant lymphoma in children by using Id4 gene methylation indicator

Objective To study and discuss what part does methylated Id4 gene participate in malignant lymphoma stage Ⅳ by detecting the extent of how much Id4 gene has been methylated in afflicted children who suffer from malignant lymphoma. Methods Forty-two patients who had diagnosed with malignant lymphoma [ Hodgkin's disease(HD), Non-Hodgkin's lymphoma(NHL)] were selected as study group.Their chemotherapy stages of pre-treatment, early-treatment, mid-treatment, post-treatment and clinical remissions or relapse throughout the entire treatment had been traced.At each stage the expression of methylated Id4 gene mRNA was detected by methylation-specific polyme-rase chain reaction (MS-PCR) and compared with the control group.The control group consisted of 20 non-neoplastic hematologic disorder affected children as sample donors. Results MS-PCR detection: in pre-treatment stage, there were 27 patients who were found methylated or partially methylated Id4 genes.Methylated ratio was thus at 64.3%(27 patients out of a total of 42 patients). Those 27 patients were actively traced down along with different stages of treatment (21 NHL patients, 6 HD patients). Before NHL there was 55.6% methylated Id4 gene (15 cases out of 27 NHL patients). During chemotherapy treatment, there was 51.9% of methylated Id4 gene positive (14 cases out of 27 patients). In post chemotherapy treatment, there was 48.1% of methylated Id4 gene positive (13 cases out of 27 patients). Totally there were 9 patients showed clinical recovery after chemotherapy.There was 44.4% of traceable methylated Id4 gene after recovered chemotherapy patients (4 recovered patients still carrying positive reading of methylated Id4 gene out of totally 9 recovered patients). There were 2 patients relapsed, with traceable methylated Id4 gene re-appeared in them afterwards.Throughout different treatment stages, there was no significant correlation in the treatment result and the appearance of methylated Id4 gene in early treatment stages (all P>0.05). But in latter treatment of chemotherapy, the correlation started to emerge (P 0.05). The control group had 20 patients, none of them had methylated Id4 gene.The study group showed noticeable difference in methylated Id4 gene before and after the experiment (P<0.001). RT-PCR result showed that before chemotherapy treatment, all of those who carried methylated Id4 gene had no expression of mRNA, by comparison to the controll group which all had expression of mRNA. Conclusions Methylated Id4 gene is closely related in affected children who suffer from malignant lymphoma and its complications.The expression of Id4 gene is depressed when it has been methylated.The state of methylated Id4 gene is changed as patient's condition changed, so the methylated Id4 gene is thus a possible indicator of early diagnostic tool for children lymphoma. Key words: Malignant lymphoma; Methylation; Id4 gene; Child