Familial alobar holoprosencephaly, also known as cyclopia, is an uncommon and fatal congenital disability as well as an uncommon type of holoprosencephaly (HPE) that happens as a consequence of the unfinished separation of the prosencephalon into two distinct parts of hemispheres throughout organogenesis, resulting in a failed cleavage of the orbital cavity into the two cavities of the eyes. This is a gradual anterior terminal seizure of the neural plate.
Moreover, the nose is usually absent or substituted for a nonfunctional nose in the shape of a proboscis. A proboscis that arises over the middle part of the eye is a symptom of rhinocephaly or rhinencephaly. Although familial alobar holoprosencephaly occurs in one out of every 16,000 live babies, cyclopia occurs in as little as one out of every 100,000 infants, like stillbirths.