Anencephaly is a severe congenital condition where a major portion of the brain, skull, and scalp is absent. It occurs during early fetal development when the neural tube does not close properly, leading to incomplete formation of the brain. Infants born with anencephaly are typically stillborn or die shortly after birth, as the condition is incompatible with sustained life. There is no cure for anencephaly, and it is often detected during prenatal screenings.