The genetic link links type 1 diabetes, autoimmune thyroid disease; Test requested
The authors of a review article explore the role of HLA antigens in type 1 diabetes and autoimmune thyroid disease.
A recent review article finds genetic links between type 1 diabetes (T1D) and autoimmune thyroid disease (AITD) and calls for regular screening for autoimmune endocrine disease in the children of these patients.
The review, published on March 10, 2021, in Frontiers in endocrinology, notes that T1D and AITD are the most common chronic autoimmune diseases in the world, but they are not the only endocrine and non-endocrine disorders that come together. T1D and AITD in particular, the authors wrote, tend to appear in families, as seen in autoimmune polyendocrinopathy (AP).
“The close relationship between these 2 diseases is largely explained by the sharing of a common genetic background,” they wrote.
The authors explored in detail the role of HLA antigens in people with a genetic predisposition to develop autoimmune disease. “There is a correlation between the carriage of certain HLA class II alleles and an increased likelihood of developing the most common autoimmune diseases, including T1D and AITD,” the authors wrote.
They explained that HLA genes are important messengers in general, and that proteins that receive HLA class II messages in particular are important in signaling T cells, which play a major role in the adaptive immune system. The authors discussed the processes in which an immune response elicits recognition by the T cell receptor on the surface of CD4 + T cells, which in turn activates B cells to produce autoantibodies, triggering an additional immune response.
“In patients with autoimmune diseases, such as T1D and AITD, autoantibodies are synthesized and lymphocytes often infiltrate the target organ, resulting in inflammation and even partial destruction,” have explained the authors. “Because antigen presentation and subsequent activation of T cells are considered key components of the immune response, it is of the utmost importance to study the peculiarities of antigen presentation as well as the structure and characteristics of HLA proteins in particular. “
The review examines other rare variants long known to be involved in immune regulation that can make a person susceptible to both T1D and AITD, some of which have previously been targets in highly effective therapies: They include the cytotoxic antigen associated with T lymphocytes (CTLA4). , non-receptor type 22 protein tyrosine phosphatase (PTPN22), interleukin-2 receptor (IL2Ra), vitamin D receptor (VDR) and tumor necrosis factor-a (TNF).
Genes and environmental factors both have a role in T1D and AITD, which the authors say are “multifactorial autoimmune endocrine diseases”, in which a few genes may increase the risk of both conditions. HLA, the authors write, “remains the largest contributor to overall risk, while additional genetic interactions are likely to confer protection or sensitivity.”
Different genes are associated with the risk of disease in people of different racial or ethnic backgrounds, which strengthens the case for the combined role of genetics, epigenetics, and environmental factors in the development of autoimmune disorders. According to the authors, this strengthens the case for genetic testing of patients with monoglandular autoimmunity, such as T1D and Addison’s disease, as well as their first-degree relatives.
“In view of the possible long interval between the first manifestation of PA and the subsequent development of other autoimmune endocrinopathies, regular and long-term observation of patients is warranted,” they wrote. “In addition, screening for autoimmune endocrine diseases is recommended regularly, especially for the offspring of patients with T1D and AITD and AP III variant.”
Frommer L, Kahaly GJ. Type 1 diabetes and autoimmune thyroid disease: the genetic link. Endocrinol before. 2021; 10 (12): 618213. doi: 10.3389 / fendo.2021.618213.