<<Disclaimer: Verify this information before applying it to your situation.>> The recent post on identical twin risk for celiac disease raises an important point on the gene(s) for celiac disease. Identical twins are genetically identical. They share all the same genes. If one has the gene(s) for a disease then the other has the same genes. The studies on the concordance of celiac disease between identical twins suggests that it is less than 100% , more like 70%. This tells us that the disease does have a strong base in genes, but something else is needed, some environmental factor to trigger the disease in a genetically susceptible host. On testing the gentically identical twin. As the risk for celiac disease so high (75%) in a seemingly unaffected twin a very careful search for it should be made and the blood tests alone may not be precise enough to rule it out entirely. There is also a possibility that the twin may not have the disease at this point but may develop it later in life and it may present differently from the other twin. The twin studies serve to illustrate the difference between a disease that is strictly genetic in it nature and one that has a genetic susceptibility. many people can have the genes but never get the disease. This is not medical advice Joseph Murray MD Coordinator, Celiac Disease Clinic University Of Iowa Iowa City IA 52242