MYD88-Mutated Chronic Lymphocytic Leukaemia/Small Lymphocytic Lymphoma as a Distinctive Molecular Subgroup Is Associated with Atypical Immunophenotypes in Chinese Patients

Chronic lymphocytic leukaemia/small lymphocytic lymphoma (CLL/SLL) is a heterogeneous disease in Western and Chinese populations, and it is still not well characterized in Chinese patients. Based on a large cohort of newly diagnosed CLL/SLL patients from China, we investigated immunophenotypes, genetic abnormalities, and their correlations. Eighty-four percent of the CLL/SLL patients showed typical immunophenotypes with scores of 4 or 5 points in the Royal Marsden Hospital (RMH) scoring system (classic group), and the remaining 16% of patients were atypical with scores lower than 4 points (atypical group). Trisomy 12 and variants of TP53, NOTCH1, SF3B1, ATM, and MYD88 were the most recurrent genetic aberrations. Additionally, unsupervised genomic analysis based on molecular genetics revealed distinctive characteristics of MYD88 variants in CLL/SLL. By overlapping different correlation grouping analysis from genetics to immunophenotypes, the results showed MYD88 variants to be highly related to atypical CLL/SLL immunophenotypes. Furthermore, compared with mantle cell lymphoma (MCL), the genetic landscape showed potential value in clinical differential diagnosis of atypical CLL/SLL and MCL patients. These results reveal immunophenotypic and genetic features, and may provide insights into the tumorigenesis and clinical management of Chinese CLL/SLL patients.