Analysis of the immunoglobulin heavy chain gene variable region of 101 cases with peripheral B cell neoplasms and B cell chronic lymphocytic leukemiain the Japanese population

We have analyzed the immunoglobulin heavy chain (VH) gene variable regions (CDR2 and FW3) of 101 Japanese cases with peripheral a cell neoplasms, When all except one case with a deletion were graphed by frequency of replaceme nt mutation, the 100 cases could be separated into two groups: 24 cases wit h zero, one and two mutations (germline or tow frequency of somatic mutatio n); and 76 cases with three or more mutations (medium to high frequency of somatic mutation). While most mantle cell lymphoma cases (11/13) showed ger mline or low frequency of somatic mutation, all cases of mucosa-associated lymphoid tissue (MALT) lymphoma (11/11), follicular lymphoma (three of thre e cases), plasma cell myeloma (seven of seven cases) and most cases of diff use large B cell lymphoma (DLBCL; 42/47) belonged to the latter group. Thes e 76 cases, therefore, may be considered to show somatic hypermutation. Mor e than half of chronic lymphocytic leukemia/small lymphocytic lymphoma case s (CLL/SLL; eight of 13) showed a hypermutated VH gene and the ratio of rep lacement mutation:silent mutation in CDR2 of CLL/SLL was considerably highe r compared with DLBCL and MALT lymphoma, showing somatic hypermutation, Whe n comparing VH gene type of a cell-CLL (B-CLL) among our series and those i n the literature, more cases of CD5(+) B-CLL in the Western literature have the VH5 and VH6 family types, while more cases in Japan are reported to ha ve VH4 family. The occurrence of VH families in B-CLL between Japanese and Western people seems to be comparable.