BALF concentrations of NGF and neurotrophin-3 (NT-3) were significantly increased, and immunoreactivity against NGF, BDNF, NT-3, and tyrosine protein kinase receptors (TrkA, TrkB, and TrkC) in granulomas was found in patients with sarcoidosis using immunohistochemical analysis [33]. The gene discussed is NTRK2; the disease is sarcoidosis.