Abstract
We report a case of Down syndrome (DS) associated with chronic thyroiditis having positive various autoantibodies and mild hypothyroidism. A boy aged 3 years and 9 months showed growth disturbance. Tests revealed mild hypothyroidism and various autoantibodies. There were several antithyroid antibodies, as well as ANA, anti-dsDNA, anti-RNP antibody but no clinical features of lupus. Although anti-dsDNA antibody is negative in Hashimoto's thyroiditis, our DS patient with chronic autoimmune thyroiditis showed various antinuclear antibodies, including anti-dsDNA. The immunological mechanism of chronic immune thyroiditis in DS patients may differ from that in Hashimoto's thyroiditis. In DS patients, chronic autoimmune thyroiditis may be influenced by immune abnormalities associated with trisomy 21.
