“…Congenital hypothyroidism is commoner in DS (Fort et al, 1984), although its aetiology is unclear. Early studies with proteinbound iodine (Simon et al, 1954), radioactive iodine uptake (Friedman, 1955) and T3 resin uptake (Pearse et at., 1963;Saxena & Pryles, 1965) showed that there was no consistent change in thyroid function associated with DS. However, acquired autoimmune thyroid disease is common and often occurs prematurely; thus, hyperthyroidism, and more particularly hypothyroidism, are well recognized to occur with increased frequency in DS (for review of early case reports see Aarskog, 1969).…”