<prompt> Answer this question truthfullyWhat is the definition of Behçets disease?  <response>: <reason> Common risk factors in the development of Behcet disease may be occupational, environmental, genetic, and viral. Behçets disease can affect people in any age, but the most common age is 2030 years old. Behçets disease is more common in Middle East and Japan then in other race. It is rare in America. Researches demonstrate that the presence of the gene HLA B51 is a risk factor for Behçets disease. 