Today's Malady: Keeping One Eye Open

After much hullabaloo over Cy, the kitten born with one eye, I bring you Today's Malady: Holoprosencephaly, which is the condition that Cy suffered from.

What are the characteristics of Today's Malady?

According to this article by the National Institute of Neurological Disorders and Stroke, holoprosencephaly is the failure of the prosencephalon or forebrain to divide properly. A brain with holoprosencephaly may look like this, this (quite dramatic - this is the alobar form, meaning there is no division into hemispheres) or perhaps this (semilobar - there is a cleft representing some, but not sufficient, separation of hemispheres).

Causes of holoprosencephaly include chromosomal disorders such as trisomy 13, maternal diabetes, and of course, sporadic occurance with no known cause. Alobar and semilobar holoprosencephaly with features like those of Cy the Kitten are more common among embryos than among live births, as the conditions are generally incompatible with life.

This article over at Zygote: a Developmental Biology Website is quite informative, and includes pictures of the spectrum of holoprosencephaly from severe afflictions incompatible with life, to the more mildly afflicted who may have less severe facial deformities, but may have epilepsy, hydrocephalus (fluid on the brain), varying degrees of mental retardation, and other abnormalities.