In the multivariable analysis, higher baseline serum IgM levels were associated with increased risk of severe infections (HR: 1.005; 95% CI: 1.002 to 1.009; p=0.006), whereby a higher baseline total CD19+ B cell number (HR: 0.995, 95% CI: 0.991 to 0.999; p=0.011) and TMP/SMX pophylaxis (HR: 0.232; 95% CI: 0.087 to 0.623; p=0.004; figure 2A) with decreased risk of severe infections. The gene discussed is CD19; the disease is infection.