Similar to other SCIDs, JAK3 deficiency patients normally present with recurrent severe respiratory infections, refractory diarrhea, thrush, and/or retarded growth, characterized by irrecoverable infections mostly caused by opportunistic and/or multiple pathogens (2, 5, 6, 8, 14) or live-attenuated vaccination (5, 6, 8–11). Here, JAK3 is linked to respiratory tract infectious disorder.