Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online.Zadik Barak Levin Syndrome (ZBLS) is a congenital disorder in humans. Presenting conditions include primary hypothyroidism, cleft palate, hypodontia, and ectodermal dysplasia. It is the result of an embryonic defect in the mesodermal-ectodermal midline development.Congenital disorder involves defects in or damage to a developing fetus. It may be the result of genetic abnormalities, the intrauterine (uterus) environment, errors of morphogenesis, or a chromosomal abnormality. The outcome of the disorder will further depend on complex interactions between the pre-natal deficit and the post-natal environment.Congenital disorders vary widely in causation and abnormalities. Any substance that causes birth defects is known as a teratogen.