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Researchers using the world’s largest twin registry to study seven autoimmune diseases found the risk of developing the seven diseases is largely inherited, but that some diseases are more closely related than others.
“These results contribute to our understanding of what causes autoimmunity and how autoimmune diseases are related,” said Jakob Skov MD, the study’s lead investigator and a PhD student at the Karolinska Institute in Stockholm, Sweden. “We examined the risk of acquiring not only one specific disease, but any one in a cluster of conditions. The findings may be helpful in patient education and autoimmune risk counselling.”
By using data on 116,320 twins from the Swedish Twin Registry, which is managed by the Karolinska Institute, they found that Addison’s disease, a type of adrenal insufficiency; coeliac disease, or gluten intolerance; and Type 1 diabetes, are strongly influenced by genes with heritability greater than 85%, while environmental factors contribute to disease for Hashimoto’s hypothyroidism, a form of underactive thyroid; the skin disease vitiligo; Graves’ disease, an overactive thyroid; and atrophic gastritis, a chronic inflammation of the stomach.
Autoimmune clustering was high in Addison’s disease and vitiligo, the researchers found, but low in coeliac disease.
“Our results indicate that Addison’s disease and vitiligo often overlap with other disorders, whereas coeliac disease more rarely associates with the other diseases,” Skov said.
