Cretinism is a congenital disease caused by lack of thyroid hormone in late fetal life and early infancy which interferes with normal development, including that of the brain. It may be due to congenital inability to secrete the hormone or, in certain areas of the world, to lack of dietary iodine (which is needed for hormone formation). The typical appearance, with coarse skin, puffy face, large tongue, and slow responses, usually enables early diagnosis.