Typing for major histocompatibility complex class II antigens in thyroid tissue blocks: association of Hashimoto's thyroiditis with HLA-DQA0301 and DQB0201 alleles

Genetic Susceptibility to Joint Occurrence of Polycystic Ovary Syndrome and Hashimoto's Thyroiditis: How Far Is Our Understanding?

Polycystic ovary syndrome (PCOS) and Hashimoto’s thyroiditis (HT) are endocrine disorders that commonly occur among young women. A higher prevalence of HT in women with PCOS, relative to healthy individuals, is observed consistently. Combined occurrence of both diseases is associated with a higher risk of severe metabolic and reproductive complications. Genetic factors strongly impact the pathogenesis of both PCOS and HT and several susceptibility loci associated with a higher risk of both disorders have been identified. Furthermore, some candidate gene polymorphisms are thought to be functionally relevant; however, few genetic variants are proposed to be causally associated with the incidence of both disorders together.

General and Specific Genetic Polymorphism of Cytokines-Related Gene in AITD

Autoimmune thyroid disease (AITD) shows the highest incidence among organ-specific autoimmune diseases and is the most common thyroid disease in humans, including Graves' disease (GD) and Hashimoto's thyroiditis (HT). The susceptibility to autoimmune diseases is affected by increased autoantibody levels, susceptibility gene polymorphisms, environmental factors, and psychological factors, but the pathogenesis remains unclear. Various cytokines and related genes encoding them play important roles in the development and progression of AITD. CD152, an expression product of the CTLA-4 gene, downregulates T cell activation. The A/A genotype polymorphism in the CT60 locus may reduce the production of thyroid autoantibodies. The C1858T polymorphism of the PTNP22 gene reduces the expression of its encoded LYP, which increases the risk of GD and HT. GD is an organ-specific autoimmune disease involving increased secretion of thyroid hormone, whereas HT may be associated with the destruction of thyroid gland tissue and hypothyroidism. These two diseases exhibit similar pathogenesis but opposite trends in the clinical manifestations. In this review, we focus on the structure and function of these cytokines and related genes in AITD, as well as the association of polymorphisms with susceptibility to GD and HT, and attempt to describe their differences in pathogenesis and clinical manifestations.

Immunogenetics of Hashimoto's thyroiditis

Hashimoto's thyroiditis (HT) is an organ-specific T-cell mediated disease. It is a complex disease, with a strong genetic component. To date, significant progress has been made towards the identification and functional characterization of HT susceptibility genes. In this review, we will summarize the recent advances in our understanding of the genetic input to the pathogenesis of HT.

HLA-DRB1 polymorphism determines susceptibility to autoimmune thyroiditis in transgenic mice: definitive association with HLA-DRB1*0301 (DR3) gene

Familial clustering of autoimmune thyroid diseases has led to studies of their association with human major histocompatibility complex (MHC) class II genes. One such gene implicated in Hashimoto's thyroiditis (HT) is HLA-DR3, but the association is weak and is contradicted by other reports. On the other hand, murine experimental autoimmune thyroiditis (EAT), a model for HT, presents a clear linkage with MHC class II. Moreover, it is inducible with thyroglobulin (Tg), the common autoantigen in either species. Immunization of HLA-DRB1* 0301 (DR3) transgenic mice with mouse or human Tg resulted in severe thyroiditis. In contrast, transgenic mice expressing the HLA-DRB1*1502 (DR2) gene were resistant to EAT. Our studies show that HLA-DRB1 polymorphism determines susceptibility to autoimmune thyroiditis and implicate Tg as an important autoantigen.