 At least 40 % of people with aphthous stomatitis have a positive family history , suggesting that some people are genetically predisposed to suffering with oral ulceration . HLA @-@ B12 , HLA @-@ B51 , HLA @-@ Cw7 , HLA @-@ A2 , HLA @-@ A11 , and HLA @-@ DR2 are examples of human leukocyte antigen types associated with aphthous stomatitis . However , these HLA types are inconsistently associated with the condition , and also vary according to ethnicity . People who have a positive family history of aphthous stomatitis tend to develop a more severe form of the condition , and at an earlier age than is typical . 
