Importantly, CTLA-4 polymorphisms have been linked to autoimmune conditions including type I diabetes (96, 97), Hashimoto's thyroiditis (97, 98), systemic lupus erythematous (99, 100) and celiac disease (101), indicating possible roles for non-hematopoietic tissue CTLA-4 in the ontogeny and progression of autoimmune disease. Here, CTLA4 is linked to Hashimoto thyroiditis.