Thus, the aim and novelty of the present study were to evaluate the serum BDNF, tropomyosin receptor kinase B (TrkB, the main BDNF receptor) and neurofilament light chain protein (Nfl, a biomarker of neurodegeneration) in infants hospitalized with bronchiolitis at discharge and their correlation with the clinical manifestations and RSV infection severity. The gene discussed is BDNF; the disease is bronchiolitis.