Cat Eye Syndrome

Cat eye syndrome (CES) is a rare condition usually caused by a small section of the short arm (p) as well as the long arm (q) of human chromosome 22 being present in a trisomic manner (three times) or a tetrasomic manner (four times) instead of the normal two. This implies that there’s presence of an extra small chromosome derived from chromosome 22, which happens to be smaller than chromosome 21. Chromosome 21 is usually the smallest chromosome in human beings. Technically, this chromosome represents a duplication and inversion of the chromosome band 22q11p. The name cat eye was derived from the cat-like appearance of the iris of the victim’s eye ("Medical Definition of Cat eye syndrome", 2016).

The cat eye syndrome is medically referred to as a constitutional chromosome abnormality displayed by the combination of no anal opening (aka anal atresia) and a cat-like slit of the iris of the patient’s eye (aka vertical coloboma). The presence of the syndrome can occur at birth or even before birth. The following can also occur frequently:

•         kidney anomalies

•         heart malformations

•         tissue tags or pits in front of the ears and

•         down slanting eye slits (palpebral fissures)

Unlike many other constitutional chromosome abnormalities, there’s usually near-normal or normal development with this type of syndrome. Victims of cat eye syndrome also exhibit near-normal or normal intelligence. Synonyms for the cat eye syndrome include ("Cat Eye Syndrome", 2011):

•         Chromosome 22, Partial Trisomy (22pter-22q11)

•         CES

•         Schmid-Fraccaro Syndrome

•         Chromosome 22, Inverted Duplication (22pter-22q11)

•         Chromosome 22, Partial Tetrasomy (22pter-22q11)

Some of the major features associated with cat eye syndrome include the following (Timoney & MacNicholas, 200, p. 20):

•         Performance and behavior – mild conductive deafness

•         Nose – minimal epicanthal folds and a depressed nasal bridge

•         Ears – prominent anthelices, Preauricular skin tags or fistulae, atresia of auditory canals and hypoplastic ear lobes

•         Head and Neck – retrognathia and micrognathia

•         Urogenital System – hydronephrosis, bladder fistula, and kidney hypoplasia or aplasia

•         Eyes – occasional microphthalmia, hypertelorism, coloboma, microphthalmia, and downslanting palpebral fissures

•         Gastrointestinal System - mobile caecum and anal atresia 

•         Growth and development – mild to moderate growth retardation and mental retardation

•         Cardiovascular system - tricuspid atresia, ventricular septal defect, persistence of left superior vena cava, anomalous pulmonary venous return, absence of the inferior vena cava, and tetralogy of Fallot.

Only one person can have the cat eye syndrome between 50,000 to 150,000 individuals in the world. As mentioned earlier, it affects many body parts including the heart, ears, eyes, and kidneys. A child born with this condition might experience mild learning or developmental delays, problems with speech, or behavior issues. He or she may also have a below average height and have missing ribs, fused vertebrae, dislocated hips or a curved spine (medically known as scoliosis). Moreover, kids with the cat eye syndrome may also experience trouble when hearing because of the way their ears are shaped ("What Is Cat Eye Syndrome?” 2016) These impairments are likely to affect the performance of children with CES in the classroom since they can tend to score very low grades. Poor grades can be attributed to their inability to see and hear well or perceive sound or even write well due to weak limbs or curved spine. Their general body weakness and defects can also lead to frequent absenteeism in school.