Source: Endocrine Society
As part of researching whether autoimmune diseases are related to each other, this time we present two independent studies in this field, namely a study of twins in Sweden and a study of a gene that affects several autoimmune diseases of the Center for Applied Genomics at Children’s Hospital of Philadelphia.
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 were presented at ENDO 2019, the Endocrine Society’s annual meeting in New Orleans, USA.
“These results contribute to our understanding of what causes autoimmunity and how autoimmune diseases are related,” said Jakob Skov, M.D., the study’s lead investigator and a Ph.D. 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.”
Autoimmune diseases tend to run in families. The basis of twin studies is to examine concordance rates—the likelihood of both twins in a pair having the same disease. Higher concordance rates in identical than in non-identical twins point to genetic influence. This information is typically used to calculate heritability—a measure of how much of the variation in disease risk is due to genetic factors. Skov and his co-workers also looked at the likelihood of both twins in a pair having different autoimmune diseases—which they named “pseudoconcordance” – and compared these rates to measure autoimmune clustering.
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; celiac disease, or gluten intolerance; and type 1 diabetes, are strongly influenced by genes with heritability greater than 85 percent, 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.
“Our results indicate that Addison´s disease and vitiligo often overlap with other disorders, whereas celiac disease more rarely associates with the other diseases,” Skov said.
As many autoimmune diseases occur in families, and because individual patients often have more than one autoimmune condition, there is a possibility that these conditions have a common genetic predisposition. Dr. Hakon Hakonarson, director of the Center for Applied Genomics at the Children’s Hospital of Philadelphia (CHOP), conducted a study covering 10 clinically different autoimmune diseases that occurred in childhood: type 1 diabetes, celiac disease, juvenile idiopathic arthritis, often variable immune deficiency , systemic lupus erythematosus, Crohn ‘s disease, ulcerative colitis, psoriasis, autoimmune thyroiditis and ankylosing spondylitis.
The research presents a systematic analysis of multiple diseases that occur in children at the same time. Hakonarson, who said: “27 gene signals have been discovered, one of which encodes a ligand for the CD40 receptor, which is linked to Crohn’s disease, ulcerative colitis and celiac disease. This ligand may present a promising target for the treatment of these diseases.”
Among several diseases, genes with stronger expression in B cells have been observed. For example, “diseases such as lupus or juvenile idiopathic arthritis have B cell dysfunctions, which may lead to the development of therapies to address excessive expression. ” (Hakonarson, 2019).
Such research provides insight into the possibilities of treating multiple autoimmune diseases simultaneously and more accurately targeting gene networks in inhibiting specific autoimmune diseases. Also, such research has a significant impact on the early diagnosis of multiple autoimmune diseases.
The article is a translation of The Endocrine Society.
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