Genetic Involvement in Type I Diabetes

One of the services offered on our GGC web site is called “Ask a Geneticist a Question”. This service is designed to provide expert, professional responses to genetic and health questions.

Recently a site visitor from Massachusetts submitted a question concerning juvenile diabetes. The viewer wanted to know what genetic factor or combination of genes had to be present in a child in order to contract the disease. Because diabetes is such a common complex disease in our society, I wanted to share this information with you.

Type 1 diabetes (juvenile type diabetes) is commonly diagnosed in children and young adults. The disease is characterized by a lack of insulin production which is needed to transport glucose from the blood into the cells of the body. Consequences associated with type 1 diabetes include hypoglycemia or low levels of blood glucose, hyperglycemia or high glucose levels that prompt many complications, and ketoacidosis or high ketone or acid levels which can accumulate and lead to diabetic coma.

Dr. Steve Skinner, a GGC clinical geneticist, responded to this specific question stating:

“Type 1 diabetes (juvenile type) is an autoimmune disorder, meaning that the body's own immune system attacks itself causing the destruction of the islet cells in the pancreas. Viruses are one of the environmental triggers thought to set off the autoimmune response. There does appear to be a genetic predisposition or susceptibility to the development of type 1 diabetes. There are at least 18 different genetic locations on 8 different chromosomes that are associated with this genetic predisposition. Each of these 18 genetic locations may contain several genes associated with diabetes. Some of the gene variations at these locations can cause an increase risk and some can give a protective effect. Many of these individual genes have not been determined yet. There is no available test that looks at the many variations possible at all these locations to give an individual risk factor. The two most well known genes associated with an increased risk are located in the HLA locus on chromosome 6. The alleles HLA DR3 and HLA DR4 give an increased risk for developing type 1 diabetes. The HLA DR2 allele appears to have some protective effect. Having a certain combination of genes does not mean an individual will automatically develop diabetes, but they are at increased risk compared to others with a different genetic make-up.”

For additional information on this condition you may visit The American Diabetes Association web site at www.diabetes.org.

Special thanks to Steve Skinner, M.D.