We drew our study population from the 77,469 subjects in the screening group. Initially, we identified 129 subjects with incident CLL in the database; of these subjects, 123 had given their consent to participate in research studies. Forty-six of the 123 subjects had available prediagnostic cryopreserved whole blood. For one subject, the stored blood contained an insufficient number of cells for our analysis. Therefore, 45 subjects with CLL were eligible for our study. For all subjects, a blood sample had been obtained at least 3 months before the date of diagnosis. We also included 10 subjects without a CLL diagnosis as negative controls.
