According to the latest issue of the journal Nature Genetics, the largest genetic study of post-traumatic stress disorder (PTSD) to date has identified 95 loci (i.e. positions in the genome) associated with PTSD risk, including 80 previously undiscovered loci. This result may help explain why some people suffer from PTSD. The discovery by researchers from the Massachusetts Institute of Technology and the Broad Institute at Harvard University confirms that heritability is a core characteristic of PTSD and once again confirms the genetic factors that contribute to the complexity of PTSD. Researchers have compiled data from 88 different genome-wide association studies, involving risk information for PTSD among over 1.2 million people in Europe, Africa, and the Americas. Data analysis revealed 95 loci closely related to PTSD, of which 43 seem to play a role in causing PTSD. Researchers have found that PTSD and depression share many common genetic characteristics. Although previous studies have found that the incidence of PTSD in women is higher than that in men, researchers have not found any evidence in their data. They examined the X chromosome and identified 5 loci associated with PTSD, but these changes on the X chromosome will have similar effects on both males and females. The study also found that the cerebellum, which controls movement and balance, may be associated with this disease. The intermediate neurons connecting motor neurons and sensory neurons are also associated with an increased risk of PTSD. Future research may help determine how key genes in these tissues and cells affect PTSD symptoms and behavior. (Lai Xin She)