November 29, 2005
Genetics and Heredity
Question from Center Barnstead, New Hampshire, USA:
My fiance has type 1 diabetes. He is 30 and has had diabetes since age four. His father also has type one diabetes. My fiance’s brother did not develop diabetes, but died at age 18. My fiance’s paternal grandfather also has diabetes. Those are the only family members on his side of the family who we know have been diagnosed. Type 1 and type 2 diabetes do not run in my family. What are the chances that our child(ren) will develop diabetes? How early can it be diagnosed? Are there special precautions to take during or after pregnancy when baby is at risk for developing diabetes? Is it likely to be diagnosed within toddlerhood? Any thoughts or stats you have would be appreciated. The diabetes specialists we’ve seen (haven’t spoken with genetics crew yet) have just indicated that, obviously, it is possible because of the family history.
Answer:
The risk of a child developing diabetes when father has type 1 diabetes is approximately 4 to 6%. With other family members also having type 1 diabetes, the risk goes up, perhaps to the 6 to 10% range. There are not many things that one can do to prevent diabetes, at the moment, that are safe. Some experimental interventions are theoretically promising, but we worry about side effects particularly when interfering with normal immune system, cancer, etc.
There are two nutritional interventions that are also promising, but not conclusive. One is breast feeding infants for as long as a year, exclusively. This was originally thought to provide protection via the mom’s immune system but, more recently, it has been concluded that breast feeding also, obviously, avoids other nutritional triggers such as those from cow milk proteins and those from wheat/gluten. Therefore, avoiding cow milk proteins in formula feeding and also strictly avoiding all wheat/gluten products has some research support for prevention of type 1 diabetes in a genetically susceptible child.
Lastly, if one knew the genetic HLA type of the parents and then the child, an expensive proposition, then one could better assess genetic risk. This is more a research tool at the moment but also has some theoretical promise.
So, the bottom line is: the risk for a child under such circumstances are about 90% against developing type 1 diabetes.
SB