Holoprosencephaly

• Failure of the prosencephalon (the embryonic forebrain) to sufficiently divide into the double lobes of the cerebral hemispheres.
• The result is a single-lobed brain structure and severe skull and facial defects.
• In most cases of holoprosencephaly, the malformations are so severe that babies die before birth.
• In less severe cases, babies are born with normal or near-normal brain development and facial deformities that may affect the eyes, nose, and upper lip