Recently, Izumi et al. described the cooccurrence of PKS and Burkitt lymphoma, strengthening the suspicion of a link between isochromosome 12p and tumorigenesis, with several genes located in the PKS 12p critical region (such as ETV6, KRAS, CCND2, CDKN1B, and AICDA) known to play roles in tumor development [20]. The gene discussed is CDKN1B; the disease is tetrasomy 12p.