DNA methylation of promoter-associated CpG islands is an epigenetic modification of DNA associanted with gene silencing. p73 is a member of the p 53 family which is a tumor suppressor gene producing apoptosis and cell cycel arrest. We investigated the methylation pattern of p73 on the cases diagnosed at Ewha university hospital between 1993-2002.

Sixteen cases of NK/T cell lymphomas and 7 cases of normal controls, which were 2 cases of peripheral blood mononuclear cells and 5 cases of nasal mucosal tissue were studied. Methylation-speific PCR for p73 were done.

All cases of NK/T cell lymphomas except one(93.8%) showed hypermethylation of p73. Six cases among 7 normal control cases(14.2%) revealed unmethylated p73.

This results suggested that inactivation of p73 could be associated with tumorigenesis of NK cells.

Epstein-Barr virus(EBV) is associated with development of various types of lymphoma, especially NK/T cell lymphoma. Recently, its subtypes and LMP-1, major oncoprotein of EBV, have been studied. We investigated the frequency of EBV, its subtypes, and LMP-1 status on the cases diagnosed at Ewha university hospital between 1993 and 2002.

Sixteen cases of NK/T cell lymphomas were studied. In situ hybridization for EBER-1 mRNA and PCR for EBV subtypes and 30 base pair deletion of LMP-1 were done.

All cases showed EBV positivity by EBER in situ hybridization. All cases contained Type A viruses and 10 cases(62.5%) revealed LMP-1 30bp deletion.

EBV act as a causative role in the development of NK/T cell lymphoma. The exact role of LMP-1 30bp deletion variant in the lymphomatogenesis should be studied with larger number of cases.