Further underscoring the relevance of TP53 aberrations and the IGHV gene SHM status, these markers were included in the CLL international prognostic index (CLL-IPI) (26), along with age, β2M levels and stage, which risk-stratifies patients into four categories (low, intermediate, high and very high risk). This evidence concerns the gene B2M and B-cell chronic lymphocytic leukemia.