Distinctive immunoglobulin VH gene usage in Japanese patients with chronic lymphocytic leukemia.

The incidence of chronic lymphocytic leukemia (CLL) is low in Asian countries including Japan, while CLL is the most common type of leukemia in the west. To elucidate which factors contribute to the low frequency of CLL in Japan, we investigated immunoglobulin (Ig) heavy chain gene usage and somatic hypermutation status in 44 Japanese patients with CLL. Only one of these patients used V(H)1-69. The finding is in striking contrast to data from western countries, where the frequency of CLL expressing V(H)1-69 ranges from 12 to 21%.