I also have the same combination, ulcerative colitis, Coeliac disease and autoimmune hepatitis. The specialist thought that was unusual, maybe not so. I had Coeliac disease diagnosed around 2 years of age (went off the diet in my late teens as I was diagnosed as not having celiac disease, Ulcerative Colitis in my late 20's and autoimmune hepatitis in my 40's diagnosed when I went back on the diet (I was asymptomatic, only had the test by chance). My theory is this is related to stress. The last 2 diseases hit at times of extreme stress, maybe activating my rogue immune system. Because I was asymptomatic, sticking to the celiac disease diet is hard as I don't feel any different if I eat gluten. I am now on long term immunosuppressants. 3 autoimmune diseases is plenty.