Patient P264, who also carried the known p.Ala181Glu variant in TNFRSF13B, was found to carry an undescribed variant (c.207C>A; p.Ser69Arg) in STAT3. Patient P101 had a history of decreased IgA levels in serum, autoimmune cytopenia, splenomegaly, enteropathy, ILD and recurrent pneumonias; whereas patient P264 suffered from recurrent respiratory infections, atopic dermatitis, mild lymphoproliferation, celiac disease, chronic diarrhea, and arthralgias. Here, TNFRSF13B is linked to susceptibility to pneumonia measurement.