What is anencephaly?

Anencephaly is defined as a severe congenital condition characterized by the absence of a major portion of the brain, skull, and scalp. Specifically, individuals with this condition are born without parts of the brain and specifically, the cerebrum, which is responsible for vital functions such as thinking, sensation, and movement. The condition arises during the early stages of fetal development when the neural tube, which eventually forms the brain and spinal cord, fails to close completely.

This condition is associated with a very limited life expectancy, as the majority of affected infants die shortly after birth. The focus on the congenital nature highlights that anencephaly is a developmental defect that occurs prenatally, distinguishing it from other conditions.

The other choices do not pertain to the definition of anencephaly. The presence of extra limbs or a birth defect affecting the heart describes different congenital disorders. Improvement of brain function does not correlate with the life-threatening implications of anencephaly. Therefore, the accurate understanding of anencephaly is encapsulated well in the choice describing it as a congenital absence of brain and spinal cord.