Increased Incidence of Extrathyroidal Congenital Malformations in Japanese Patients with Congenital Hypothyroidism and Their Relationship with Down Syndrome and Other Factors

Much remains unknown regarding extrathyroidal congenital malformations (ECMs) in patients with primary congenital hypothyroidism (PCH) and Down syndrome (DS). Here, we investigated the frequency of ECMs in patients with PCH, particularly among patients with or without DS.In a retrospective review of questionnaires based on medical records, ECMs were identified in 1520 patients with PCH and were compared with congenital malformations among...