1. Health

Cat Eye Syndrome

Caused by Genetic Defect in Chromosome 22


Updated June 14, 2014

Close up of woman's eye.
Dougal Waters/Digital Vision/Getty Images
Cat eye syndrome, named after how it affects the appearance of the eyes, is caused by a genetic defect in chromosome 22. There is a wide range of symptoms associated with the syndrome. Cat eye syndrome affects both males and females, and is estimated to occur in 1 in 74,000 individuals. Many individuals born with the syndrome are the only ones in their families who have it.


About 41 percent of individuals with cat eye syndrome have three symptoms in common:
  • absence of tissue from the colored part of one or both eyes (iris coloboma)
  • small growths of skin (tags) or depressions in the skin (pits) of the outer ears
  • an absence or obstruction of the anus (anal atresia)
In addition, individuals with cat eye syndrome may have:

Many other less common birth defects have been noted in individuals with cat eye syndrome.


Since cat eye syndrome is inherited, a child is born with it. Diagnosis is usually based on the symptoms present. Genetic testing can confirm the presence of the specific genetic defect in chromosome 22 (tripling or quadrupling of parts of the chromosome) that is associated with the syndrome.


Treatment of cat eye syndrome focuses on the symptoms the individual has. Some children may need surgery to repair birth defects in the anus or heart. Life expectancy is not significantly reduced in those individuals who do not have life-threatening physical problems (such as a severe heart defect).


Cat Eye Syndrome.” Chromosome 22 Central. Chromosome 22 Central Inc. 11 Apr 2007 <http://www.nt.net/~a815/cateye.htm>.

Godinho, R.N., I.J. Keogh, G.M. Morales, N. Calixto, & T.M. Gonsalves. "Partial tetrasomy of chromosome 22: genetic and surgical implications for otolaryngologists." Ear Nose Throat Journal 83(2004): 748, 750, 752.

Schinzel, A., W. Schmid, M. Fraccaro, L. Tiepolo, O. Zuffardi, J.M. Opitz, J. Lindsten, P. Zetterqvist, H. Enell, C. Baccichetti, R. Tenconi, & R.A. Pagon. "The "cat eye syndrome": dicentric small marker chromosome probably derived from a no.22 (tetrasomy 22pter to q11) associated with a characteristic phenotype. Report of 11 patients and delineation of the clinical picture." Human Genetics 57(1981): 148-158.

Turleau, C. "Cat-eye syndrome." OrphaNet. Dec 2005. OrphaNet. 11 Apr 2007 <http://www.orpha.net/consor/cgi-bin/data.php?ActType=Pat&Form=Pat&PatId=246.0>.

  1. About.com
  2. Health
  3. Rare Diseases
  4. Information by Disease Type
  5. Chromosome Disorders
  6. Cat Eye Syndrome Genetic Birth Defect

©2014 About.com. All rights reserved.

We comply with the HONcode standard
for trustworthy health
information: verify here.