What is a defining characteristic of Cat Eye Syndrome?

Cat Eye Syndrome is defined by the presence of a supernumerary chromosome, specifically an additional chromosome 22, leading to a tetrasomy of the 22q11 region. This extra genetic material is responsible for the characteristic features associated with the syndrome, which can include coloboma (a defect in the eye), ear anomalies, and anal atresia, among others.

In the case of Cat Eye Syndrome, the presence of the additional chromosome enhances the expression of these developmental issues. The genetic mechanism typically involves a duplication or extra copy of the 22nd chromosome, which is salient in understanding the associated clinical manifestations.

Other chromosomal abnormalities referenced, such as deletions on different chromosomes, are linked to other syndromes or disorders and do not characterize Cat Eye Syndrome. Understanding this distinct genetic marker helps in diagnosing and providing genetic counseling related to Cat Eye Syndrome.