The role of retroelements of the human genome in the development of type 1 diabetes mellitus

Retroelements (retrotransposons and endogenous retroviruses) are a class of mobile genetic elements that move in the genome by inserting their own reverse transcribed transcripts. They serve as drivers of epigenetic regulation; therefore, individual characteristics of the distribution of retroelements in the genome influence the development of multifactorial diseases. Type 1 diabetes mellitus is a multifactorial disease with an immune response against pancreatic β cells. The role of heredity in the development of the disease is estimated at 88%, and the role of allelic variants of various genes is determined. There are also other specific types of diabetes mellitus, which account for more than 2% of cases of diabetes mellitus and are monogenic diseases with an autosomal dominant mode of inheritance due to germline mutations in the MODY genes, including HNF4A, GCK, HNF1A, HNF1B. Most patients with type 1 diabetes have the protein product and ribonucleic acid (RNA) of the insulin inhibitor HERV-W-Env, which is caused by abnormal expression of the human endogenous retrovirus (HERV). An assumption has been made about the role of retroelements in the development of type 1 diabetes mellitus. This is due to their involvement in the phylogenetic formation of the endocrine system, since in evolution retroelements turned out to be sources of regulatory sequences of hormone genes, nuclear hormone receptors and binding sites for them. Type 1 diabetes mellitus is associated with the integration of HERV into the HLA-DQ gene region, with allelic variants and sizes of VNTR variable tandem repeats (part of the SVA retroelements), which regulate the expression of the insulin gene and other hormones. For this reason, it is likely that the development of type 1 diabetes mellitus may be based on individual characteristics of the distribution of HERVs in the human genome and their dynamic changes in ontogenesis. HERVs also play a role in the etiopathogenesis of diabetes mellitus through the activation of an autoimmune response, the triggering factors of which are exogenous viral infections and stress. Thus, retroelements are involved in various mechanisms of the development of type 1 diabetes mellitus, which reflects their global regulatory influence on endocrine regulation.