From Memphis, Tennessee, USA:
At the time of diagnosis of type 1 diabetes three months ago, my four year old daughter had no symptoms. Her increased blood sugar was caught by a yearly well-child exam. Her islet-cell antibody test was negative and no other antibody tests were done (GAD). We assumed that her diabetes was likely caused by exposure to the Coxsackie virus approximately six months before diagnosis, and recently, my 19 month old daughter had the Coxsackie virus.
I realize that siblings of people with type 1 diabetes generally have a 5-7% chance of also developing the disease. Does a known exposure to an environmental stressor that caused type 1 diabetes in a sibling increase the percentage probability that the sibling will develop it? If so, what would the likely percentage be?
I neither know of nor have been able to find any figures that show the degree to which an enteroviral infection might modify the overall risk figure for typeá1A (autoimmune) in an exposed first degree relative. That said, I think that there are still some questions that you might discuss with your older daughter's doctor.
There has indeed been some evidence, especially from Finnish studies, that Coxsackie infections can induce a form of autoimmune diabetes through a process called molecular mimicry where fragments of the virus resembling more usual autoantigens become bonded to antigen presenting cells in such a way as to induce autoimmunity to islet cells. However, it is usual to develop conventional antibodies especially anti-insulin antibodies. In a number of more recent studies, this notion has been accepted for cytomegalovirus infections, but is now disputed in relation to the Coxsackie viruses.
The negative islet cell antibody screening test rather suggests that your eldest daughter may not have type 1A diabetes even though it is by far the most common form in Caucasian families in the US. The matter could still be settled by repeating the antibody test, but for the now more conventional one for anti-GAD, anti-insulin and ICA 512/IA2. If your first daughter is indeed antibody negative, then it might be that she has typeá1B diabetes, a form in which insulin independence may recur after a number of months. This is rare in Caucasian families, but greater than 50% of new onset cases in African American and Hispanic families. Yet another possibility, especially as her diabetes was discovered as an abnormal random blood sugar is that she might have typeá2 diabetes, even without being significantly overweight.
Original posting 11 Jun 2002
Posted to Research: Causes and Prevention
Last Updated: Tuesday April 06, 2010 15:09:33
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