Malignancy-specific immunophenotypic abnormalities in CD4+/CD8− T-cells (e.g., conspicuously dim expression of CD2, CD3, CD4, CD5, or CD45; or conspicuously increased light scatter) should further prompt strong consideration of a T-cell neoplasm in the appropriate clinical setting. This evidence concerns the gene CD4 and T-cell and NK-cell neoplasm.