
November 28, 2004
Diagnosis and Symptoms, Genetics and Heredity
Question from DeKalb, Illinois, USA:
My nine year old daughter was diagnosed type 1 just a little more than a week ago. Her father was type 1, onset at age 17. He passed away when she was two. Before she was born, because I was an older mom, I had amniocentesis. In the medical information they took from my husband and me, we let them know that he was type 1, juvenile onset. We asked them to check her genetically for diabetes, as well as the other genetic issues that children of older parents face (just so we could be prepared for it since type 1 was in both our families). In the report, they did not find that she was at risk for type 1. In fact, when I saw some of the symptoms of diabetes, I dismissed them because I thought her genetic information had cleared her from being at risk. Did the geneticist make a mistake? Or, were there other factors that came about for her to get diabetes?
Answer:
There is no specific gene for type 1 diabetes so, it is unlikely that the geneticists made a mistake. It would depend upon what tests they did, however, and what they were looking for. Knowing specific HLA gene types for you and her father, they would theoretically be able to see if she had the same or different HLA haplotypes on the amniocentesis. But, this just provides very generalized risk information. The actual risks percentages for mothers having a child with diabetes are in the 2 to 5% range and for father’s having a child with diabetes in the 3 to 6% range. This does not help much in your situation. The best genetic counseling advice that one can provide for children of those with type 1 diabetes is that ANY symptoms that sound like diabetes should be investigated and not dismissed since that is the only sure way to know. There are research protocols available that look for these genes and also look at antibodies, but they are all not as specific as we would like them to be.
SB