
August 15, 2007
Genetics and Heredity
Question from Glen Ridge, New Jersey, USA:
My eight-year-old son has two sisters and a father with type 1 diabetes. He has celiac disease, as does his father and one of his sisters. I have hypothyroidism. We have a lot of autoimmune issues, as you can see. Every time my son seems a little thirstier or crankier than usual or simply more tired than usual, I stick his finger and check his blood sugar. Rightfully so, our endocrinologist told me to leave him alone. He said that if I get nervous, I should just check his urine. My son is part of the TrialNet study and, every year, we anxiously wait for his results. So, here is my why DOESN’T my son have type 1 diabetes? How likely is it (best guess?) that he will get it? Why does my family have so many autoimmune issues?
Answer:
The last question is probably the easiest for me to guess at – you have certain genes on the short arm of the 6th chromosome in what is called the HLA region. These are susceptibility genes that increase or decrease chances for disease like autoimmune diseases. It is likely that these are in the B8, B15, DR3, DR4 subgroups which increase autoimmune disorders like type 1 diabetes, thyroiditis, celiac disease. You should ask your medical team if they have actually HLA typed your family since this would explain some of the clustering you described. Whether or not one or another person actually gets one of these diseases depends upon things that we do not totally understand, i.e., exposure to cows’ milk proteins, gluten/wheat, other environmental factors such as viruses and other chemicals.
I would think that occasional checking of blood glucose levels in this child is not so difficult or onerous and, so, would check myself with blood glucose levels and not with urine glucose levels. I leave this to you and your family to decide.
SB