MRGPRX2 is a multiligand receptor expressed by MCs (14), which responds to a broad variety of exogenous and endogenous stimuli, e.g., insect venom, drugs, neuropeptides such as cortistatin (CST) and substance P (SP), eosinophil granule proteins including major basic protein (MBP) and eosinophil cationic protein (ECP), and infections (15–19). The gene discussed is RNASE3; the disease is infection.