[1358] Complex Chromosomal Abnormalities in TEL-AML1-Positive Acute Lymphoblastic Leukemia Is Associated with High White Blood Cell Count in Pediatric Patients.

Yao Schmidt, Amy McGranahan, Xiayuan Liang. The Children's Hospital, Aurora, CO; University of Colorado Denver School of Medicine, Aurora

Background: TEL-AML1 (ETV6-RUNX1) is a recurrent genetic abnormality in B-acute lymphoblastic leukemia (ALL) and is usually associated with a favorable outcome in pediatric patients. Most of cases with TEL-AML1 have a simple cryptic translocation and show a normal karyotype by conventional cytogenetic analysis with detection of TEL-AML1 by FISH and/or RT-PCR. A subset of cases has other chromosomal abnormalities in addition to TEL-AML1, and some of these cases have complex karyotypes. Also, some cases with TEL-AML1 are clinically more aggressive than others. To investigate if additional cytogenetic abnormalities play a role in an aggressive disease process, we examined karyotype, S-phase fraction (SPF, a cell proliferation indicator), and white blood cell count (WBC) in a series of B-ALL with TEL-AML1translocation in pediatric patients.
Design: 50 cases of B-ALL with TEL-AML1 at The Children's Hospital, Colorado from 2000 to 2010 which have a complete karyotype available are included in this study. The complex karyotype is defined as ≥ 3 chromosomal structural abnormalities in addition to TEL-AML1 or ≥ 2 abnormal clones with ≥ 3 additional chromosomal structural abnormalities. TEL-AML1 translocation was tested by either FISH and/or RT-PCR study. SPF was analyzed by flow cytometry. SPF >10% was defined as a high SPF.
Results: Cases with complex karyotypes more frequently carry high WBC (> 50,000) than cases with normal karyotypes (P = 0.044). A high cell proliferation rate also is seen more often in cases with complex karyotypes than cases with normal karyotypes.

Table 1

TEL-AML1 translocation	# of Cases	S-phase (>10%)	WBC (>50,000/mm3)	P value
Normal karyotype(simple cryptic TEL-AML1)	27	2/24 (8%)	3/27 (11%)
Non-complex karyotype	14	1/13 (8%)	1/14 (7%)
Complex karyotype	9	2/9 (22%)	4/9 (44%)	0.044

Conclusions: TEL-AML1-positive ALLs with complex karyotypes are associated with high WBC and are more often to have a high cell proliferation rate. These findings suggest that complex chromosomal abnormalities in TEL-AML1-positive ALL may be associated with more unfavorable outcome than cases with a simple cryptic TEL-AML1 translocation and may represent a distinct subgroup of TEL-AML1-positive ALL.
Category: Hematopathology

Wednesday, March 2, 2011 9:30 AM

Poster Session V # 159, Wednesday Morning