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Disease Profile

Cat eye syndrome

Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.

1-9 / 100 000

US Estimated

Europe Estimated

Age of onset





Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease.


Autosomal recessive Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype.


dominant X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.


recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder.


Mitochondrial or multigenic Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.


Multigenic or multifactor Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.


Not applicable


Other names (AKA)

Schmid-Fraccaro syndrome; CES; Chromosome 22 partial tetrasomy;


Chromosome Disorders; Congenital and Genetic Diseases; Digestive Diseases;


Cat eye syndrome is a chromosome abnormality that affects many different parts of the body. The signs and symptoms of the condition vary widely but may include abnormalities of the eyes, ears, anal region, heart and/or kidney.[1][2] In people affected by cat eye syndrome, each cell has at least one small extra (duplicate) chromosome made up of genetic material from chromosome 22. This extra genetic material leads to the characteristic signs and symptoms of the condition.[3] Most cases of cat eye syndrome occur sporadically in people with no family history of the condition. Treatment is symptomatic.[2]


The signs and symptoms of cat eye syndrome vary, but may include:[1][2][4]

  • Iris coloboma
  • Anal atresia (opening to the anus is missing)
  • Skin tags or pits in front of the ears
  • Unusually shaped ears
  • Conductive hearing loss
  • Hypertelorism (widely spaced eyes)
  • Downward slanting palpebral fissures (outside corners of the eyes point downward)
  • Strabismus
  • Cleft lip and/or palate
  • Congenital heart defects
  • Urinary tract problems
  • Skeletal abnormalities
  • Developmental delay
  • Mild to moderate intellectual disability

This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

Medical Terms Other Names
Learn More:
80%-99% of people have these symptoms
Anal atresia
Absent anus
Preauricular pit
Pit in front of the ear
Preauricular skin tag
30%-79% of people have these symptoms
Abnormal localization of kidney
Abnormal localisation of kidneys
Abnormality of cardiovascular system morphology
Abnormality of the ribs
Rib abnormalities
Chorioretinal coloboma
Birth defect that causes a hole in the innermost layer at the back of the eye
Downslanted palpebral fissures
Downward slanting of the opening between the eyelids
Hip dysplasia
Wide-set eyes
Widely spaced eyes

[ more ]

Intellectual disability, mild
Mental retardation, borderline-mild
Mild and nonprogressive mental retardation
Mild mental retardation

[ more ]

Intrauterine growth retardation
Prenatal growth deficiency
Prenatal growth retardation

[ more ]

Iris coloboma
Cat eye
Muscular hypotonia
Low or weak muscle tone
Renal hypoplasia/aplasia
Absent/small kidney
Absent/underdeveloped kidney

[ more ]

Short stature
Decreased body height
Small stature

[ more ]

5%-29% of people have these symptoms
Abnormality of the genital system
Genital abnormalities
Genital abnormality
Genital anomalies
Genital defects

[ more ]

Hearing impairment
Hearing defect

[ more ]

Abnormally small eyeball
Percent of people who have these symptoms is not available through HPO
Abnormal heart morphology
Abnormality of the heart
Abnormally shaped heart
Heart defect

[ more ]

Absent radius
Missing outer large bone of forearm
Autosomal dominant inheritance
Biliary atresia
Cleft palate
Cleft roof of mouth
Growth abnormality
Abnormal growth
Growth issue

[ more ]

Intestinal malrotation
Low-set ears
Low set ears
Lowset ears

[ more ]

Little lower jaw
Small jaw
Small lower jaw

[ more ]

Renal agenesis
Absent kidney
Missing kidney

[ more ]

Stenosis of the external auditory canal
Narrowing of passageway from outer ear to middle ear
Total anomalous pulmonary venous return


Cat eye syndrome is most often caused by a chromosome abnormality called an inverted duplicated 22. In people with this condition, each cell has at least one small extra (duplicate) chromosome made up of genetic material from chromosome 22. This extra genetic material leads to the characteristic signs and symptoms of cat eye syndrome.[3]


A diagnosis of cat eye syndrome is often suspected based on the presence of characteristic signs and symptoms. Genetic testing can then be ordered to confirm the diagnosis. This testing may include:[2][5]

  • Karyotype a karyotype is a laboratory test that produces an image of a person's chromosomes.
  • FISH a laboratory technique that is used to detect and locate a specific DNA sequence on a chromosome. During FISH, a chromosome is exposed to a small DNA sequence called a probe that has a fluorescent molecule attached to it. The probe sequence binds to its corresponding sequence on the chromosome.

In some cases, cat eye syndrome can be diagnosed before birth. If suspicious features are observed on prenatal ultrasound, follow up testing such as an amniocentesis or chorionic villus sampling may be ordered to further investigate a diagnosis.[2][5]

Testing Resources

  • The Genetic Testing Registry (GTR) provides information about the genetic tests for this condition. The intended audience for the GTR is health care providers and researchers. Patients and consumers with specific questions about a genetic test should contact a health care provider or a genetics professional.


    Because cat eye syndrome affects many different systems of the body, medical management is often provided by a team of doctors and other healthcare professionals. Treatment for this condition varies based on the signs and symptoms present in each person. For example, congenital heart defects; anal atresia; cleft lip and/or palate; and certain skeletal abnormalities may require surgery. Children with delayed motor milestones (i.e. walking) may be referred for physical therapy or occupational therapy. Special education services are often necessary for children with intellectual disability.[1][2][4]


    Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

    Organizations Supporting this Disease

      Learn more

      These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

      Where to Start

      • MedlinePlus Genetics contains information on Cat eye syndrome. This website is maintained by the National Library of Medicine.
      • The National Organization for Rare Disorders (NORD) has a report for patients and families about this condition. NORD is a patient advocacy organization for individuals with rare diseases and the organizations that serve them.

        In-Depth Information

        • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
        • Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
        • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
        • PubMed is a searchable database of medical literature and lists journal articles that discuss Cat eye syndrome. Click on the link to view a sample search on this topic.


          1. Cat-eye syndrome. Orphanet. January 2016; https://www.orpha.net/consor/cgi-bin/OC_Exp.php?lng=en&Expert=195.
          2. Cat Eye Syndrome. NORD. 2017; https://www.rarediseases.org/rare-disease-information/rare-diseases/byID/1085/viewAbstract.
          3. Chromosome 22. Genetics Home Reference. September 2016; https://ghr.nlm.nih.gov/chromosome/22.
          4. Rosa RF, Mombach R, Zen PR, Graziadio C, Paskulin GA. Clinical characteristics of a sample of patients with cat eye syndrome. Rev Assoc Med Bras. July-August 2010; 56(4):462-465.
          5. Cat Eye Syndrome. OMIM. 2009; https://www.ncbi.nlm.nih.gov/omim/115470. Accessed 12/15/2016.

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