Evidence for aberrant V(D)J rearrangements in 73-deficient thymocytes was obtained by assaying for internal deletion at the Bcl11b and Notch1 loci, which both contain cryptic recombination signal sequences (RSS) that are accessible to Rag, and are frequently mutated in T cell lymphomas [28]–[30]. This evidence concerns the gene BCL11B and T-cell non-Hodgkin lymphoma.