One of the most frequent associations is with gastrointestinal autoimmune disorders, including celiac disease (CD) and gluten-related conditions (GRC) (i.e., non-celiac gluten/wheat sensitivity—NCGS; incidental finding of positive anti-tissue transglutaminase antibodies—anti-tTG—without clinical symptoms or histological confirmation of CD), whose frequency is elevated in patients with HT (2%–9% of overall HT patients) (4, 6–8). The gene discussed is TGM2; the disease is Cowden disease.