For example, the NLGN1 gene is localized in excitatory synapses and plays an important role in learning and memory; knockout of NLGN1 can lead to loss of fear memory storage, and variation in NLGN1 may predispose individuals to experiencing higher levels of anxiety and fear, potentially increasing their risk of developing PTSD after a traumatic event [13]. This evidence concerns the gene NLGN1 and post-traumatic stress disorder.