Diagnostic Study of Gene Alterations in Children Who Have Been Treated for Relapsed Acute Lymphocytic Leukemia

OBJECTIVES: * Determine the incidence of p16/p15 homozygous deletions and p15 promoter hypermethylation in acute lymphocytic leukemia cells of children treated on protocol CCG-1941. * Determine the prognostic importance of p16/p15 abnormalities in these children. * Determine the presence or absence of p16/p15 abnormalities in the dominant clone at diagnosis if present at relapse in these patients. OUTLINE: Frozen cells are obtained from samples collected on protocol CCG-1941. DNA is isolated and examined using Southern blot analysis to assay for deletions and promoter hypermethylation of p16 and/or p15. PROJECTED ACCRUAL: Approximately 100 samples will be obtained for this study.