December 7, 2000
Research: Causes and Prevention
Question from Duluth, Minnesota, USA:
My four year old daughter was diagnosed at 28 months of age, and my 21 month old son was just diagnosed. My son tested negative for antibodies in the DPT-1 about a year ago. Is there a way to get a probability of future children developing type 1 diabetes? The only relative with type 1 is my husband's first cousin (a male diagnosed in college). Where can my husband and I get a blood test for HLA? Should the kids have this test too?
If you take a large cohort of Caucasian children in the U.S. or Western Europe, the chances of a future sibling getting autoimmune diabetes in childhood or the teen years where a parent or sibling already has the condition is about 6%, plus or minus 3%, depending on geography and genetic makeup.
For a variety of reasons I don’t believe that at the present time this figure can be further refined by HLA typing of you and your husband or the children, but it is interesting to speculate.
In the first place, your son was antibody negative nine months before he developed clinical diabetes. Therefore, he could be still negative in which case he would be classified as type�1B diabetes. About half of these children have at-risk HLA types and the other half neutral or even protective HLA types. Again, about half these children can manage for a time without insulin, but the relationship of this subgroup to HLA Type is not yet defined.
I think it is much more probable that both of the children have autoimmune or type�1A diabetes, and that the early negative antibody test was based on the less reliable ICA immunofluorescent screening test and not on the definitive three antibody anti-GAD,anti insulin and anti-ICA 512 one.
If you and your husband were typed you would know the incidence of high, moderate, low or even protective alleles that might be combined in future children, but without a much better understanding of what the environmental factors are that trigger autoimmunity, you would still not be able to assess risk more exactly If however you would like to try this approach rather than trusting to future advances in preventing and managing type 1 diabetes, you can arrange to get the tests done.