Increased trisomy 12 frequency and a biased IgVH 3–21 gene usage characterize small lymphocytic lymphoma

Small lymphocytic lymphoma (SLL) and chronic lymphocytic leukemia (CLL) are considered as similar entity by the WHO classification. We assessed the distribution of the four prognostic cytogenetic markers (deletion 11q23, 13q14, 17p13 and trisomy 12) and VH mutational status in 32 SLL and 119 CLL. Trisomy 12 was most frequent (36% vs 13%, p = 0.014) and 13q14 deletion was less frequent (9% vs 44%, p = 0.001) in SLL in comparison with CLL. An over representation of VH3–21 gene usage was found in SLL (17% vs 1%, p = 0.011). In conclusion, SLL show specific genetic markers that distinguish them from classical CLL.