Other relevant characteristics of TEL/AML1-positive ALL are frequent deletion of the other TEL allele and association with an excellent prognostic outcome.     ///    "This alteration, which results in the production of a TEL/AML1 chimeric protein, is restricted to pediatric B-lineage acute lymphoid leukemia (ALL), where it represents the most frequent molecular defect known to date (up to 25% of cases). "