Our data are in line with Chu et al. and Gonzales-Gomez et al. [5,8] analyzing the DNA methylation of CDKN2B, DAPK1, GSTP1, MGMT, MLH1, RARB, THBS1, TIMP2, and TIMP3 in PCNSL by MSP (Additional file 8) further supporting the validity of our analysis. The gene discussed is TIMP2; the disease is primary central nervous system lymphoma.