NEW YORK (Reuters Health) - New research suggests that certain gene variants that increase the risk of type 1 diabetes also raise the risk of celiac disease, according to research published online today by The New England Journal of Medicine.

People with celiac disease can't tolerate gluten -- a protein in wheat, rye and barley that is also found in spelt, durum semolina, couscous, and many processed foods. Ingredients like modified starches and MSG, as well as condiments like soy sauce, can all contain gluten.

When celiacs eat food containing the "edible glue," it triggers an immune response that damages the small finger-like villi in the intestinal wall, which absorb nutrients from food. When they are damaged, a person can become malnourished; some celiacs suffer from osteoporosis or iron deficiencies. The disease is treated by going on a gluten-free diet, which allows the small intestine to recover.

"It has been known for a long time that there is clinical overlap of about 3 percent between the two diseases," senior author Dr. John A Todd told Reuters Health. "Because of this, we knew there might be shared genes."

"The big surprise is that almost every celiac disease gene is involved in type 1 diabetes, and that the causes of these diseases overlap considerably," he added. "Even though the clinical overlap is small, the basic (underlying) overlap was much larger than we expected."

Todd, at the University of Cambridge, UK, and co-investigators evaluated the relationships between non-HLA loci associated with type 1 diabetes and celiac disease. Their analysis was based on genotyping of DNA from 8064 patients with type 1 diabetes, 3064 parent-diabetic child trios, 2560 patients with celiac disease, and 9339 controls.

In a genetic analysis of over 20,000 subjects, the researchers confirmed the existence of 11 genetic regions associated with celiac disease, three of which are also linked to type 1 diabetes.

Of 21 genetic regions associated with type 1 diabetes, two have an association with celiac disease.

Also, seven genetic regions on chromosome 2 are shared between the two diseases.

"Our results spotlight that much more research needs to go into investigating the environmental factors involved and why autoimmune diseases are increasing," Todd said.

Also, he added, "More research should be directed to identifying common genetic factors and investigating whether there are benefits for type 1 diabetics knowing they are positive for celiac."

SOURCE: The New England Journal of Medicine, December 10, 2008.

Copyright © 2006 Reuters Limited. All rights reserved. Republication or redistribution of Reuters content, including by framing or similar means, is expressly prohibited without the prior written consent of Reuters. Reuters shall not be liable for any errors or delays in the content, or for any actions taken in reliance thereon. Reuters and the Reuters sphere logo are registered trademarks and trademarks of the Reuters group of companies around the world.