A recurrent heterozygous somatic mutation in the DNA-binding domain (DBD) of IRF4, consisting of a substitution of a leucine with an arginine at the position 116 of the amino acid sequence (p.L116R, c.347T > G), was detected in 1.2–2% of CLL patients [55–58]. This evidence concerns the gene IRF4 and B-cell chronic lymphocytic leukemia.