We know that about 30% of all the genetic regions in the genome that are linked to coeliac disease are also linked to other autoimmune diseases, and that this overlap is especially large for type 1 diabetes. We are really interested in finding out what these regions do exactly, and hope in that way to find out what the shared disease mechanism between type 1 diabetes and coeliac disease is. This would help us predict who is more likely to develop both in the future, but unfortunately, we are not there yet.
As for Dermatitis herpetiformis (DH), we are not really sure why DH happens in some coeliac patients. Unlike other autoimmune diseases, we don’t know the genetic link behind DH, so it’s hard for us to understand how some individuals get DH and others don’t.