- Mutations in the gene encoding paired box domain (PAX8) are not a frequent cause of congenital hypothyroidism (CH) in Iranian patients with thyroid dysgenesis. Mahjoubi, F., Mohammadi, M.M., Montazeri, M., Aminii, M., Hashemipour, M. Arq. Bras. Endocrinol. Metabol (2010)