A post-mortem histology study suggested that BDNF expression is region-specific and that levels were higher in the cerebellum in Rett syndrome patients (Pejhan et al., 2020a) although a study by the same group using ELISA (quantifying protein levels) suggested BDNF levels were lower in all regions (Pejhan et al., 2020b); more detailed study of BDNF and IGF-1 expression in anxiety regions may be helpful for understanding its mechanism in Rett syndrome. The gene discussed is IGF1; the disease is Rett syndrome.