Chromosomal Analysis in Childhood Leukemia

Ki, Mi Na; Kim, Eun A; Lyu, Chuhl Joo; Yang, Chang Hyun; Kim, Kir Young; Choi, Jong Rak

Abstract

PURPOSE: Chromosomal analysis has been helpful not only in pathophysiology of leukemia, but diagnosis, classification, management and predicting prognosis. However, little has been studied on chromosomal abnormality of pediatric leukemia in Korea. We have performed chromosomal analysis on childhood leukemia that we experienced, and tried to correlate chromosomal abnormalities with various types of leukemia.
METHODS
Subjects were 28 of 84 patients diagnosed with leukemia and have been discovered to have chromosomal abnormalities on chromosomal analysis employing G-banding technique in Yonsei medical center from July 1996 to February 1999.
RESULTS
Of the total 84 patients, Acute lymphocytic leukemia (ALL) accounted for 51 cases (61%), Acute myelocytic leukemia (AML), 30 cases (35%), Chronic myeloid leukemia (CML), 3 cases (4%). Chromosomal analysis in ALL: Of 51 cases, 9 cases (18%) showed chromosomal abnormality. Their mean age at diagnosis was 5.6+/-5.1 years. One case (12%) exhibited hyperploid (> 50 chromosomes), 4 cases (44%) pseudodiploid, and marginally-hyperdiploid was seen in 4 cases (44%). Structural abnormality involving translocation was seen in 6 cases, where t(3;9), t(4;11), t(12;?) 1 case respectively, del (13) 2 cases, and I (q9) 1 case. Chromosomal abnormality in AML: Of total 29 cases, 17 cases (55%) were found to have chromosomal abnormalities, with their mean age ranging 7.6+/-6.4 years. t(8;21) was found to be the largest, accounting for 5 cases, and t(15;17), t(1;22), t(1;11), t(10;11), del(5), inv(9) 1 case respectively, 21 trisomy in 1 case, 11 trisomy in 1 case. Other complex chromosomal abnormality was seen in 2 cases. Upon analysis of relationship between the chromosomal abnormality and FAB subtypes, 4 cases of M2- subtype were found amongst 5 cases of t(8;21), but the other chromosomal abnormalities and subtypes failed to show any correlation. Chromosomal abnormality in CML: Two cases (67%) of chromosomal abnormalities were found in 3 with CML. Their mean age at diagnosis was 152.7 years, and all cases showed t(9;22).
CONCLUSION
Our study found that in pediatric AML, t(8;21) showed high incidence and was found to be related with M2-subtype. In CML, t(9;22) was found to be frequent, but the data lacks in accuracy as our sample was too small. For more precise information on incidences of chromosomal abnormalities and the prognostic implications that the cytogenetic properties of leukemia, further studies seem to be essential.