Hyperthyroidism, a form of thyrotoxicosis, is a clinical state characterized by inappropriately high tissue thyroid hormone levels.1 The prevalence of hyperthyroidism ranges from 0.1% to 2.9% worldwide2 and is approximately 1.2% (0.5% overt and 0.7% subclinical) in the United States. This evidence concerns the gene TG and hyperthyroidism.