Environmental factors also play a role in the etiology of the disease, such as stress, humidity, cold infectious agent and cigarette smoking It has been suggested that developed ra might be a response to an incentive in a genetically susceptible host Environmental factors also play a role in the etiology of the disease，such as stress, humidity, cold, infectious agent and cigarette smoking  It has been suggested that developed RA might be a response to an incentive in a genetically susceptible host