Thyroid autoimmunity is familial.[1] The disease is said to be inherited as a dominant trait since it has been reported that as many as fifty percent of the first degree relatives of patients with some type of autoimmune thyroiditis present with thyroid antibodies in serum.[1] Some studies have even related it to chromosome 21 because of its high correlation with patients with Down’s syndrome and familial Alzheimer’s disease. This theory is controversial, since patients with Turner’s syndrome also present a high prevalence of autoimmune thyroiditis (up to fifty percent).[1]