Neither of these factors, including Rai stage and β2‐microglobulin, were associated with IgG levels in a study by Mauro et al., but low IgA was more frequently found in patients with splenomegaly and CD38 positivity and low IgM was found in those with higher lymphocyte counts and in Rai stage 0–II.6 This evidence concerns the gene CD40LG and Splenomegaly.