BCL2 and B-cell chronic lymphocytic leukemia: In the CLL cells of a fourth patient, we found a non-reported nonsynonymous BCL2 mutation (BCL2A113P) that results in an alanine to proline substitution at amino acid position 113 of BCL2. Review of the known tertiary structure of BCL2 revealed that this mutation causes a substitution of proline for an alanine at a position contiguous to the BH3-binding pocket (Fig. 3A).