3.14 The Influence of Genetic Background and Infectious Exposure on the Development of Chronic Lymphocytic Leukaemia and Other B-Cell Malignancies: Evidence from High-Sensitivity Screening in Leeds and Rural Uganda

Chronic lymphocytic leukaemia (CLL) is the most common leukaemia in the EU and US, but is reported to be rare in sub-Saharan Africa where splenic B-cell lymphoma is more frequent. However, accurate population incidence data are difficult to obtain. CLL-type monoclonal B-cell lymphocytosis (MBL) is detected in 5-20% of adults in the EU/US. The disorder always precedes but does not always progress to CLL. The age and sex distribution of cases with more than 10 CLL cells/μL matches that of clinical disease but with 100-fold higher prevalence. Non-CLL MBL is less common in the EU and US, with a prevalence of approximately 1%. Assessment of MBL in different populations may provide insight into the genetic and environmental factors that contribute to disease progression.