Participants with Plasmodium infection and splenomegaly had a higher proportion of raised plasma/serum IgM (60.0% vs 18.4%, P = .006), and adults with splenomegaly had a higher proportion of neutropenia (60.0% vs 11.1%, P = .011) (Supplementary Table 4). The gene discussed is CD40LG; the disease is neutropenia.