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Diagnosis and Treatment

Diagnosis

Diagnosis criteria typically requires at least two of the ocular coloboma, anal atresia, and renal malformations; or one of the above accompanied by minor symptoms; or the combination of any five or more minor symptoms [1]. Cat Eye Syndrome is estimated to afflict 1 in 50,000 to 1 in 150,000 [2].

Preauricular pits and tags, and mild retardation of development and growth– which have a frequency of occurrence of 87% and 50% respectively—are other serious symptoms that encourage a CES diagnosis [3].

These diagnoses are verified cytogenetically: usually in the form of FISH (fluorescence in-situ hybridization) analysis. FISH confirms the presence of a “Type I” or “Type II” Cat Eye Syndrome chromosomes [4]. “Type I” is the more common cause of CES [5]. Researchers have been unable to find a correlation between chromosome type and phenotype severity due to conflicting clinical findings.

FISH analysis of CES patient

What is FISH analysis?

Although FISH is often used by medical professionals there is currently no standard test used to diagnose CES. Cytogenetic blood testing is another popular method used. Both will confirm the presence of the supernumerary marker chromosome [6]. In rare cases the marker chromosome will not be present. It is theorized that this occurs when the marker chromosome in present during embryonic development but disappears afterwards [7]. Only a handful of CES patients have been noted to have this variation of CES.

Individuals who would like to obtain more information are encouraged to contact local health services to access cytogenetic services. Those in the Greater Vancouver area can obtain this service through Vancouver Coastal Health lab services.

Prenatal diagnosis of CES is also made possible by FISH. Further details, such as fetal phenotype, can be obtained via 3D ultrasounds: however, the phenotype may not be definitive as case studies have shown individuals to develop new symptoms over time. See picture of a 3D ultrasound. Amniocentesis is another prenatal diagnostic method through the search for the presence of the supernumerary marker chromosome.

Treatment

Treatment is largely dependent on the phenotype of the patient and the severity of symptoms. Ocular coloboma cannot be corrected; however, eyesight can be improved using prescription eyewear in mild cases. In addition, heart and anal malformations and hernias can usually be corrected using surgery. Skin tags can also be removed by simple procedures.

Health professionals will judge which treaments to use on a case-by-case basis.

Those interested in participating in clinical trials can go to the Chromosome 22 Central webpage and our News webpage to see a list of ongoing trials.

Condition specific treatment options:

Pulmonary venous malformations– estimated frequency is 29-43% [8]; Generally accepted to occur at birth and commonly causes large visible bumps in the skin. The majority of malformations can be treated individually by placing medical glue or alcohol in the affected site to prevent it from filling from blood. The procedure is minimally invasive and requires a short recovery period [9].

Anal atresia-- estimated frequency is 73-81% [13]; Due to the serious consequences of anal atresia, surgery is usually performed soon after birth to correct the problem. It is confirmed using x-ray or ultrasonography prior to treatment. Recovery is usually fast and without complications [10].

Preauricular tags/pits– common trait found in infants; in most cases tags and pits do not need to be treated. Pits will usually cause less physiological problems than tags but infections may occur. Minor surgery can be performed if hearing problems are a concern and will be recommended by a physician [11].

Hypogonadotropic hypogonadism is a condition experienced by very few CES patients. However, in 1998 a 17 year old boy with CES did show hypogonadotropic hypogonadism resulting in the patient having short stature and no secondary second characteristics. He had no pubic hair, facial hair, and decreased bone and muscle mass. Hormonal replacement therapy was started and after one year the secondary sex characteristics developed resulting in the patient increasing in height by 12 cm, by weight by 8 kg and bone age became that of a 16 year old. This case study is an example of Hormonal replacement therapy being an excellent treatment for hypogonadotropic hypogonadism, a rare but possible symptom of Cat Eye Syndrome [12].

Hyperactivity– If severe this can be dealt with prescription medication and psychological counselling. This treatment option is commonly used in non-CES and DiGeorge Syndrome patients experiencing hyperactivity.

References

1. Chen, H. (2006). Cat eye syndrome. Atlas of genetic diagnosis and counseling (pp. 136-137,138). Totowa, New Jersey: Humana Press.

2. Win, T.N., Roberts, S., & Laws, D. (2007).

Duane syndrome associated with the Cat Eye Syndrome: a case report. 21, April 20, 2012. 289-291.

3. Elliot, P., Lambiase, P.D., & Kumar, D. (2011). Inherited cardiac disease. New York, New York: Oxford University Press.

4. Liehr, T., Pfeiffer, R. A., & Trautmann, U. (1992).

Typical and partial cat eye syndrome: Identification of the marker chromosome by FISH. 42(2), March 20, 2012. 91-96.

5. Bartsch, O., Rasi, S., Hoffmann, K., & Blin, N. (2005). FISH of supernumerary marker chromosomes identifies six diagnostically relevant intervals on chromosome 22q and a novel type of bisatellited SMC(22). 13(5). 592-598.

6. Mears, A.J., et al. (1994). Molecular characterization of the marker chromosome associated with Cat Eye Syndrome. 55(1), May 15, 2012. 134-142

7. Neu, R.L., Assemany, S.R., & Gardner L.I. (1970). Cat eye syndrome with normal chromosomes. 949(1).

8. Rosa, R.F.M., et al. (2010). Clinical characteristics of a sample of patients with Cat Eye Syndrome. 56(4), April 20, 2012. 462-466.

9. http://www.hopkinsmedicine.org/vascular/conditions/malformations

10. http://www.merckmanuals.com/home/childrens_health_issues/birth_defects/digestive_tract_defects.html

11. http://www.nlm.nih.gov/medlineplus/ency/article/003304.htm

12. Masukawa, Hiroko., et al. (1998). Cat Eye Syndrome with Hypogonadotropic Hypogonadism. Internal Medicine, 37(10), 853-856.

13. Knijnenburg, J., et al. (2012). A 600kb triplication in the cat eye syndrome critical region causes anorectal, renal and preauricular anomalies in a three-generation family. 20(9), August 27, 2012. 986-989.