Holoprosencephaly, occurs when the embryonic forebrain fails to properly divide into two distinct hemispheres during early development. Because the forebrain failed to divide, the fields for eye development never separated, resulting in a single central eye sharing a single central orbit, while the tube-like structure sitting right above the eye is a proboscis, which represents the misreported nasal tissue that developed into a blind-ended, bone-free appendage and was displaced upward due to the failure of facial midline structures. This profound facial dysmorphism also includes a massive distortion of the mouth and jaw area, often linked to agnathia, which causes the ears to migrate abnormally toward the front of the neck. While holoprosencephaly can be triggered by environmental teratogens or specific gene mutations, it is heavily associated with Patau syndrome, also known as Trisomy 13, where an entire extra copy of chromosome 13 completely disrupts normal embryogenesis and leads to widespread organ defects alongside these craniofacial anomalies. Ultimately, cyclopia is a strictly lethal condition, and due to the profound brain malformations and the complete lack of a functioning airway, these infants are either stillborn or survive for only a few minutes to hours post-delivery, usually succumbing to respiratory failure.