[A study of E2A gene in childhood acute lymphoblastic leukemia]

E2A gene rearrangements and E2A-PBX1 chimeric mRNA produced by t(1;19) were examined in 50 cases with acute lymphoblastic leukemia (ALL). Nine of 10 ALL cases with t(1;19) showed the rearrangement by Southern blotting using the E2A gene probe when digested with Xba I, Bgl II, and Eco RI, and the remaining one having hyperdiploidy which was considered to be a sign of good prognosis, lacked E2A rearrangement. Six of 7 ALL cases with t(1;19) that were tested showed the predicted 164 bps band of E2A-PBX1 chimeric mRNA by reverse transcriptase-polymerase chain reaction (RT-PCR), while a case having t(1;19) without E2A rearrangement and 10 cases lacking t(1;19) did not. Three ALL cases tested did not have E2A-PBX1 mRNA at the time complete remission 4 months after diagnosis. Forty ALL cases lacking t(1;19), including 4 cases with t(11;19), did not reveal rearrangement of E2A. We conclude that t(1;19)-ALL can be molecularly diagnosed, and minimal residual disease could be detected by the RT-PCR method.