In addition, it is possible that there is currently an underreported association between MECP2, anxiety (panic disorder, phobias, generalized anxiety disorder) and stress-related disorders (posttraumatic stress disorder), and future studies in the field should screen for MECP2 variants and also methylation levels (mCA and mCpG) of specific MeCP2 target genes (CRH, AVP, BDNF), which early in development are sensitive to the environment and modulate the response to stressors later in life. The gene discussed is BDNF; the disease is stress-related disorder.