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From Illinois, USA:

Can you give me any information on the protein GAD and how it corresponds to type 1 diabetes? I have a four year old daughter who was diagnosed with type 1 about 2 months ago.


In the commonest form of diabetes in Caucasian children the process is triggered in a genetically susceptible person exposed by a so far unknown environmental process. As the islet cells are damaged, there is a leak of many proteins from their cytoplasm which may in turn provoke an antibody response. The antibodies that have been most commonly measured are islet cell antibodies (ICA), IA-2, and for more specific proteins anti insulin antibodies (IAA) or anti glutamic acid decarboxylase antibodies (GAD). GAD is a protein that is normally present in all cells. in the related condition of the Autoimmune Polyglandular Syndrome there may also be antibodies to other tissues such as the thyroid or to transglutaminase reflecting damage to the upper intestinal mucosa in celiac disease or to 21-hydoxylase indicating involvement of the suprarenal [adrenal] gland. These antibodies are thought to be a reflection of cell dissolution and not in themselves damaging.

One purpose of antibody testing is to distinguish in new onset cases between Typeá1A or autoimmune diabetes in which the test is positive from Typeá1B, which is common in Hispanic and African American children where the test is negative. In this latter type, the similar insulin dependant onset may be succeeded by a period in which the diabetes can be managed with oral hypoglycemic medications or just by diet and exercise.

Antibody testing is also widely used as a means to detect susceptibility in siblings and parents, an important step at a time when it may be possible to prevent overt clinical diabetes. The same process has been used, as it has been in New Zealand school children, to prevent Type 1A diabetes in a population at large.

As you can imagine there is a considerable literature on this subject which,if you are technically inclined, you can access through PubMed.


Original posting 8 Mar 2000
Posted to Research: Causes and Prevention


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Last Updated: Tuesday April 06, 2010 15:09:10
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