Chronic Lymphocytic Leukemia (CLL) is one of the most frequent tumors in Western countries. CLL represents 35% of all leukemias with an incidence of 3-7 per 100.000 habitants and reaches 12-15/100.000 in people over 60 years. The disease is heterogeneous; there are patients who have a long clinical evolution with a stable disease whereas others follow a progressive course with a median survival of 5-8 years. This heterogeneity is due to the existence of two major molecular groups, characterized respectively by the presence or absence of somatic mutations in immunoglobulin genes. Different genetic alterations have been identified associated with particular clinical presentations and evolution. There is also evidence of genetic predisposition, but the initiating genetic alterations are largely unknown in both sporadic and inherited cases. Today, there is no curative therapy for CLL.

As a contributing member of the ICGC, the CLL Consortium will generate a comprehensive catalogue of genetic alterations in 500 independent tumors. Normal and tumour samples with highly purified tumor cell content (>95%) and normal samples with <5% tumor cell contamination will be included.