CTLA4 and agammaglobulinemia: Similar to CTLA4+/- patients, LRBA deficiency also confers increased risk of recurrent respiratory tract infections, and most patients with homozygous or biallelic mutations in LRBA are also diagnosed in early childhood with hypogammaglobulinemia (57%), B cell lymphopenia, particularly affecting memory B cells and plasmablasts (58–60), while heterozygous carriers are healthy.