3Laboratório de Biologia Molecular, Centro de Transplante de Medula Óssea,

Chronic lymphocytic leukaemia (CLL) is a haematological malignancy for which reliable prognostic markers are needed in view of its clinical heterogeneity. In approximately 50 % of CLL patients, immunoglobulin (Ig) rearrange-ments are modified by somatic hypermutation (SHM), a process that represents a reliable prognostic indicator of fa-vourable progression. In this study, we investigated SHM in 37 Brazilian CLL patients and identified the preferential involvement of specific immunoglobulin gene families and segments through PCR-amplified fragments or subcloned fragments. Forty-one rearrangements were observed and 37 of them were functional. A 98 % homology cut-off with germinal sequences showed 18 patients (48.7%) with SHM. Unmutated cases showed a poorer clinical outcome. VH3 was the most frequent VH family, followed by VH4. The VH4-39 segment was the most frequently used, mainly in unmutated cases, while the VH3 family was predominant in mutated cases. The D3 and JH4/JH6 families were the most frequently observed. Key-words: chronic lymphocytic leukaemia, immunoglobulin rearrangements, somatic hypermutation. Received: August 29, 2007; Accepted: January 16, 2008. Chronic lymphocytic leukaemia (CLL) is the most frequent lymphoproliferative malignancy affecting adult