Unlike other anomalies of the medical world that affect only human animals, Cyclopia is one that effects both human and non-human animals. In fact, the majority of reports come from the animal world for a number of reasons. Sadly, when a report is found of a creature with this abnormality there are often misguided rumors of animal/human relationships, evil workings, and all other manner of nonsense. In reality, the condition is due to a genetic mutation and improper expression of proteins during the division of embryonic cells.
Put simply, Cyclopia which is also known by the names of Cyclocephaly, Holoprosencephaly , or Synopthalmia is the formation of only one orbit which results in a single-eyed individual. In addition to malformation of the eye there are several other deformation of the structures of the nasal passages, mouth, and in fact the brain itself.
Due to an improperly expressed SHH gene, the brains in individuals with Cyclopia does not divide into two hemispheres but rather remain as a single unit. As a result of this these individuals are left with only one of the optic and temporal lobes.
Shh is the only one of these vertebrate genes that is known to be expressed in the midline developing central nervous system. Shh is expressed early during development of the vertebrate notochord and floor plate and controls patterning of ventral cell fates of the anterolateral mesoderm, somites and motor neuron outgrowth and is expressed along the entire rostrocaudal extent of the nervous system, including the ventral forebrain and eye. ( Mutations in the C-Terminal Domain of Sonic Hedgehog Cause Holoprosencephaly; Human Molecular Genetics; Volume 6 Issue 11; 1 October 1997, Pages 1847–1853)
As there is only one of each of these crucial lobes of the brain the resulting structures form incorrectly. The nasal passages form as a single unit if at all. In many cases of Cyclopia the nose and mouth do not form or form in a way that suffocates the idividual shortly after birth. The orbits of the eyes do not divide as there is only one optic lobe present. As a result of this all other structures of the eye remain as one unit.
The main cause of Cyclocephaly is an improper expression of one of the many genes that play an important role in the formation of the brain and head of the embryo. This can be the result of genetic mutation or toxins. In fact, the toxin cyclopamine which is found in corn flower is often believed to be the cause of those cases found in grazing animals such as horses, sheep, and goats.
The abnormiality is believed to occur in 1 out of every 16,000 animals, and nearly 1 in every 200 aborted fetuses. Embryos with this abnormality often do not survive to the neonate stage and if they do many are stillborn or suffocate soon after death due to malformation of nasal and facial structures.
While the earliest documented case of cyclopia was a baby born in 1793 to a 36-year-old Swedish woman, many cases come from much more recent times.
In December of 2005 a kitten who would later be named Cy was born in Oregon. The kitten survived only one day.
A baby girl was born in 2006 in India with the condition, presenting with only a single eye in the center of her forehead. The child also survived only one day as her brain was not separated into the typical double hemisphere and she had no nasal structures which caused her problems.
In 2011 a shark fetus was found in Mexico with ony one large eye on the top of its head. This animal did not make it to birth.
A baby boy was born in India with hydrocephaly, and a severe form of cyclopia that caused him to only survive one day.
Another kitten was born in 2012 with a severe form of cyclopia. The kitten, later named Clyed was born with a single eye on top of its forehead and no nasal structures.The kitten suffocated shortly after birth.
Most recently a goat was born in May of 2017 in India with no true nasal structure, a deformed mouth, and only a single eye in the center of its face. While this little one lived longer than previous cases it too died due to severe deformation.
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