PRDM1 and extranodal nasal NK/T cell lymphoma: The deletion of 6q21 has been identified as the common genetic aberration in NK/T cell lymphoma (20–43%) [5, 10, 12], and the genes located in the region of 6q21, including POPDC3, PREP, PRDM1, ATG5, AIM1, HACE1, and FOXO3, were reasonably considered the affected candidates [7, 12, 13].