A photo of a one-eyed kitten named Cy drew more than a little skepticism when it turned up on various websites, but medical authorities have a name for the bizarre condition."Holoprosencephaly" causes facial deformities, according to the US National Institute for Neurological Disorders and Stroke.
In the worst cases, a single eye is located where the nose should be, according to the institute's Web site.
Traci Allen says the kitten she named Cy, short for Cyclops, was born on December 28 with the single eye and no nose.
"You don't expect to see something like that," the 35-year-old Allen said from her home in Redmond, Oregon.
Allen said she stayed up all night with the deformed kitten on her recliner, feeding Cy a liquid formula through a syringe.
She says she cared for the kitten the next day as well, until it died that evening.
Allen had taken digital pictures that she provided to The Associated Press.
Some bloggers have questioned the authenticity of the photo distributed on January 6.
AP regional photo editor Tom Stathis said he took extensive steps to confirm the one-eyed cat was not a hoax.
Stathis had Allen ship him the memory card that was in her camera.
On the card were a number of pictures - including holiday snapshots, and four pictures of a one-eyed kitten.
The kitten pictures showed the animal from different perspectives.
Fabricating those images in sequence and in the camera's original picture format, from the varying perspectives, would have been virtually impossible, Stathis said.
Meanwhile, Cy the one-eyed cat may be dead, but it has not left the building.
Allen said she's keeping the cat's corpse in her freezer for now, in case scientists would like it for research.
She said one thing's for certain: "I'm not going to put it on eBay."
AP - Associated Press
So.. What is Holoprosencephaly?
Holoprosencephaly is a type of cephalic disorder. This is a disorder characterized by the failure of the prosencephalon (the forebrain of the embryo) to develop. During normal development the forebrain is formed and the face begins to develop in the fifth and sixth weeks of human pregnancy. (The condition also occurs in other species, as with Cy, the Cyclops kitten.) Holoprosencephaly is caused by a failure of the embryo's forebrain to divide to form bilateral cerebral hemispheres (the left and right halves of the brain), causing defects in the development of the face and in brain structure and function.
There are four classifications of holoprosencephaly.
- Alobar holoprosencephaly, the most serious form in which the brain fails to separate, is usually associated with severe facial anomalies.
- Semilobar holoprosencephaly, in which the brain's hemispheres have a slight tendency to separate, is an intermediate form of the disease.
- Lobar holoprosencephaly, in which there is considerable evidence of separate brain hemispheres, is the least severe form. In some cases of lobar holoprosencephaly, the patient's brain may be nearly normal.
- Middle Interhemispheric Variant of Holoprosencephaly (MIHV) -- where the middle of the brain (posterior frontal and parietal lobes) are not well separated.
What are the Causes?
The cause of holoprosencephaly (HPE) is currently unknown. Often, no specific cause can be identified. Suggested risk factors include maternal diabetes, infections during pregnancy (syphilis, toxoplasmosis, rubella, herpes, cytomegalovirus), and various drugs taken during pregnancy (alcohol, aspirin, lithium, thorazine, anticonvulsants, hormones, retinoic acid). Women with previous pregnancy loss and first trimester bleeding are also more likely to have a child diagnosed with holoprosencephaly.
Although many children with holoprosencephaly have normal chromosomes, specific chromosomal abnormalities have been identified in some patients (trisomy of chromosome 13, also known as Patau syndrome). There is evidence that in some families, HPE is inherited (autosomal dominant as well as autosomal or X-linked recessive inheritance). Features consistent with familial transmission of the disease (e.g., a single central maxillary incisor) should be carefully assessed in parents and family members.
Several genes have been identified that play a role in holoprosencephaly, specifically SHH, ZIC2, TGIF, and SIX3.
Armand Marie Leroi describes the cause of cyclopia as a genetic malfunctioning during the process by which the embryonic brain is divided into two. Only later does the visual cortex take recognizable form, and at this point an individual with a single forebrain region will be likely to have a single, possibly rather large, eye (at such a time, individuals with separate cerebral hemispheres would form two eyes).
Increases in expression of such genes as Pax-2, as well as inhibition of Pax-6, from the notochord have been implicated in normal differentiation of cephalic midline structures. Inappropriate expression of any of these genes may result in mild to severe forms of holoprosencephaly.
The Extreme Form is Called Cyclopia:
Cyclopia (also cyclocephaly or synophthalmia) is a rare form of holoprosencephaly and is a congenital disorder (birth defect) characterized by the failure of the embryonic prosencephalon to properly divide the orbits of the eye into two cavities. Its incidence is 1 in 16,000 in born animals, and 1 in 250 in embryos.
Typically, the nose is either missing or replaced with a non-functioning nose in the form of a proboscis. Such a proboscis generally appears above the central eye, and is characteristic of a form of cyclopia called rhinencephaly or rhinocephaly.
Although cyclopia is very rare, several cyclopic human babies are preserved in medical museums (e.g. The Vrolik Museum, Amsterdam). There are also two known cases of children with Down Syndrome being born with one eye.
Some extreme cases of cyclopia have been documented in cats. In such cases, the nose and mouth fail to form, resulting in suffocation shortly after birth.
What Causes Cyclopia?
Genetic problems or toxins can cause problems in the embryonic forebrain-dividing process.
One highly teratogenic alkaloid toxin that can cause cyclopia is cyclopamine or 2-deoxyjervine, found in the plant Veratrum californicum (also known as corn lily or vetch weed). The mistake of ingesting Veratrum californicum while pregnant is often due to the fact that hellebore, a plant with which it is easily confused, is recommended as a natural treatment for vomiting, cramps, and poor circulation, three conditions that are quite common in pregnant women. Expecting mothers with diabetes and alcoholic mothers have a two-hundred fold chance of having a cyclopic child, most likely due to excessive amounts of toxins entering the body. Cyclopia occurs in the womb when a certain signaling protein is inhibited and causes the brain to stay a whole instead of having two distinct hemispheres, which also means one optic lobe and one olfactory lobe resulting in one eye.
