Frequency of deletion of CDKN2A (9p21) gene in T-cell lymphomas in FISH analysis

Cytogenetic investigations play an important role in the diagnosis of lymphomas. One of the recurrent aberrations in T-cell non-Hodgkin lymphoma (T-NHL) is a loss of the suppressor gene CDKN2A (9p21). The loss of this region is not seen in the karyotype; this deletion is submicroscopic in most cases.
Deletion of 9p21 was found in 29% (n = 55) of patients with T-NHL. Loss of CDKN2A was observed in 11 (55%) out of 20 cases with T-LBL/ALL, in 2 (33%) out of 6 with T-LGL and in 3 (20%) out of 15 patients with peripheral T-cell lymphoma, not otherwise specified (PTCL-NOS). Patients with MF, SS, primary cutaneous peripheral T-cell lymphomas and other sporadic subtypes of peripheral T-cell lymphomas did not show deletion of this region. In studied lymphomas with deletion we observed a heterogeneous signal pattern in most cases (over 81%). Analysis of the signal pattern of CDKN2A deletion showed clones with mono- and biallelic deletion in cells with variable ploidy. Probably, this phenomenon is related to concurrent incidence of cells which are in different stages of neoplastic transformation.