CD40LG and B-cell chronic lymphocytic leukemia: Subsequently, Corbingi et al. [23] in a retrospective study, divided a cohort of 1505 CLL patients, diagnosed between 1987 and 2016, into four groups: (1) 149 (9.9%) IgG+ve, (2) 73 (4.8%) IgM+ve, (3) 200 (13.3%) hypo-γ, and (4) 1083 (72%) with normal Ig levels and no PP.