is a defect in the closure of the neural tube during fetal development. The neural tube is a narrow channel that folds and closes between the 3rd and 4th weeks of pregnancy to form the brain and spinal cord of the embryo. Anencephaly occurs when the 'cephalic' or head end of the neural tube fails to close, resulting in the absence of a major portion of the brain, skull, and scalp. Infants with this disorder are born without a forebrain (the front part of the brain) and a cerebrum (the thinking and coordinating part of the brain). The remaining brain tissue is often exposed (not covered by bone or skin). A baby born with anencephaly is usually blind, deaf, unconscious, and unable to feel pain. Most cases are stillborn, although some infants have been reported to survive for a few hours or even a few days. Reflex actions such as breathing and responses to sound or touch may occur. Source: Genetic and Rare Diseases Information Center (GARD), supported by ORDR-NCATS and NHGRI.