1998; Bar‐On et al. 2002]. Further key features of HSAN IV are a deficit of temperature sensing [Ismail et al. 1998; Axelrod 2002] and developmental delay which becomes apparent within the first decade [Rosemberg et al. 1994]. Recently it has been shown that lack of TRKA signaling increases the susceptibility of patients to infections, in particular to Staphylococcus aureus, through a monocyte/macrophage‐specific NGF/TRKA pathway [Beiglman et al. 2009; Hepburn et al. 2014]. The gene discussed is NTRK1; the disease is infection.