Molecular And Cytogenetic Characteristic Of Pediatric TEL/AML1+ Acute Lymphoblastic Leukemia

Objective:Fluorescence in situ hybridization study of TEL/AML1 fusion and other abnormalities involving TEL and AML1 genes. Correlation with cytogenetic finding and prognostic value in children with acute lymphoblastic leukemia. According to different characters of TEL/AML1 positive signals classifying to study mechanism and clinical significance in the children suffering from acute lymphoblastic leuckamia. To study the molecular and cytogenetic characteristic of pediatric TEL/AML1+ acute lymphoblastic leukemia.Methods Prognosis was analyzed according to signal character of TEL/AML1, and combined with results of RT-PCR and karyotype. To study the time of molercular completed remission, carrying out statistics analysis to investigate the prognosis and mechanism of diseases.Results:Of the 77 positive patients,40(51.9%) patients had typical signal, with median molecular complete remission time was 33 days. The TEL/AML1 probe showed higher variation.13(16.9%) patients had TEL deletion, with median molecular complete remission time 30 days. The time of molecular complete remission in 10(12.9%) patients with extra AML1 signals was 104 days, which was longer than the patients with typical signal.12(15.6%) patients had double TEL/AML1 fusion signals and two patients had both TEL and AML1 deletions.13(16.9%) patients had two or more variant signals, however seven of them had relapsed (61.5%),including 4 patients with both one extra TEL/AML1 fusion and TEL deletion signals, one patients with two extra TEL/AML1 fusion signals and one patients with both TEL and AML1 deletion signals, one patients with both one extra AML1 and TEL deletion signals.Conlusion:Despite the favourable outcome of TEL/AML1 positive pediatric acute lymphoblastic leukemia patients,many of them relapse, which is associated with the character of TEL/AML1 positive signals. Amplification of AML1 is linked to short median molecular complete remission time in TEL/AML1+ pediatric ALL. Double TEL/AML1 fusion may indicate a poorer prognosis, especially higher relapse rates. The presence of two or more abnormal signals predicates the poorest outcome.