Chronic lymphocytic leukemia (CLL) is recognized as a heterogeneous disease. 1 Although the clinical staging systems (Rai et al2 and Binet et al3) provide useful methods of assessing patient prognosis, they do not provide an understanding of the basis of the heterogeneity. CLL cells are monoclonal B cells expressing low levels of surface immunoglobulin and, based on the expression of CD5, appear to phenotypically correspond to mantle-zone naive B cells. Because such cells normally do not pass through the lymphoid follicle during maturation, it would be expected that the V region genes that make up the immunoglobulin they express would not be mutated. But Schroeder and Dighiero4 showed that the immunoglobulin VH genes expressed in about half of a series of 75 CLL patients contained mutations as if they had matured in a lymphoid follicle.

Recent work from Hamblin et al5 and Damle et al6 has shown that the presence or absence of immunoglobulin V gene mutations predicts the natural history of the disease. They found that the presence of unmutated V genes was associated with a much poorer prognosis, even within the group of patients in Binet stage A. Importantly, Damle et al showed a strong correlation between expression of CD38 and the presence of unmutated V genes, suggesting that surface phenotyping might be able to identify patients with a poorer prognosis without the requirement for immunoglobulin gene sequencing. We have analyzed the immunoglobulin V genes in 39 of our patients (25 with familial CLL) to investigate this question further. DNA was extracted from peripheral blood lymphocytes and subjected to polymerase chain reaction (PCR) amplification using primers for the VH and VL genes, as previously reported. 7, 8 The amplified fragment was ligated into pMOS Blue T-vector and transformed into MOS Blue competent cells (Amersham Life Science, Buckinghamshire, England). Recombinant plasmids were purified from transformed bacteria and selected by restriction analysis. Nucleotide sequencing was performed as previously reported. 8 Inserts were sequenced in 2 directions and from multiple