A variety of pleasant things including osteoporosis and bowel cancer, apparently. So it's probably worth paying some attention to. Particularly as the guy who I saw was initially very dubious about it being even worth doing the tests - he seems to think too many people are being diagnosed as coeliac when the situation isn't actually significant enough to warrant it. So if my test results convinced him even given that attitude, I fear they're probably bad enough to be worth not ignoring...