Significant reductions in the annual rate of respiratory tract infections (rate ratio: 0.34; 95% confidence interval [CI]: 0.19, 0.59) and serum IgM levels (treatment effect: –1.09 g/L; 95% CI: –1.78, –0.39, P = 0.002) were observed in leniolisib-treated individuals versus standard of care. The gene discussed is CD40LG; the disease is Respiratory tract infection.