TP53 and B-cell chronic lymphocytic leukemia: Isolated mutations in the TP53 gene (monoallelic mutation) without a concurrent 17p abnormality are present in 3%-6% of CLL patients [429, 432–435] and up to 18% amongst fludarabine-refractory CLL, [436], indicating a strong association between TP53 mutations in the absence of del(17p) with rapid disease progression and poor survival in CLL.