This finding may be explained by a study of adult 5-HT neurons in mice with methyl-CpG binding protein (MeCP2) knockout; this protein interacted with and augmented DEAF1 activity, induced 5-HT1A auto-receptors, and led to a sex-dependent behavioral phenotype: females had reduced anxiety, whereas males showed increased anxiety and reduced depression-like behaviors [31]. This evidence concerns the gene DEAF1 and major depressive disorder.