Chromosome 22 Central

Compassion, Connection, Community. Stronger, together. Since 1996.

Chromosome 22 Central

Cat Eye Syndrome / Schmid Fraccaro Syndrome

Cat Eye Syndrome (CES) is a rare chromosome disorder. The name of this disorder arises due to the presence of a vertical coloboma of the iris which gives the eyes the appearance of “cat eyes,” however only half of people born with this condition have this feature.

It is also known in the medical literature as:

  • CES
  • Schmid-Fraccaro Syndrome
  • Chromosome 22 Partial trisomy or tetrasomy
  • Inverted duplication (22)(q11)

Cat-Eye syndrome is the more common name for a condition involving a partial trisomy or tetrasomy of part of chromosome 22. In most cases, a small extra “third” chromosome made up of part of chromosome 22 – the top half of chromosome 22 – the “p” arm, as well as the portion of the long arm of chromosome 22 down to the breakpoint q11.2, is found to be present either three times (trisomy) or four times (tetrasomy). Typically, this disorder arises randomly due to an error during meiosis in one of the parent’s reproductive cells. Parents who also have CES can pass it on to their children.

Common features

Clinically, CES is one of the more variable syndromes, with symptoms ranging from few and minor to severe malformations. 

  • Ears can be misshapen (both outer and inner ears), or have small ‘pits’, or extra bit of skin ‘tags’, along with possible hearing loss.
  • Eye differences:
    • The hallmark feature of cat-eye syndrome is a coloboma. This typically affects the iris in one or both eyes but can extend to other parts of the eye. In severe cases, it can affect vision.
    • Duane anomaly/syndrome
    • Strabismus
    • Hypertelorism
    • Inner epicanthic folds
    • In rare cases, reports of clouding of the cornea or absent iris have been seen.
  • Heart issues include but are not limited to Total anomalous pulmonary venous return (TAPVR), Tetralogy of Fallot, and atrial and ventricular septal defects.
  • Cleft palate has been reported (this is an incomplete closure of the roof of the mouth)
  • Renal (kidney) malformations: absence of 1 or both kidneys, hydronephrosis (swelling of the kidneys), extra kidneys, underdeveloped kidneys.
  • Hernias and other intestinal malformations such as gut malrotation, and Hirschsprung’s disease (a birth defect in which nerves are missing from parts of the intestine.) 
  • Anal atresia (AKA imperforate anus)
  • Growth hormone deficiency, shorter stature
  • Limb differences and other skeletal differences
  • Biliary Atresia (blocked bile ducts)
  • In males, there are reports of undescended testes and hypospadias.
  • Many people born with CES have normal intellectual development, however mild to moderate intellectual disability is seen. It is rare for people with CES to have severe intellectual disability, but it has been reported. 

It is important to remember that people affected by CES will rarely have all of these features, and may only have a few, or none at all. All people affected by CES will present differently.

There are reports of this condition being seen as a mosaic form – where only some of the cells have the extra chromosome 22 material.

It has been suggested in many medical journals that this condition may be underreported as people may have so few features that they are not brought to medical attention. It has been previously suggested that cat-eye syndrome is seen in 1:50,000 to 1:150,000 births (Schinzel et al, 1981), however, it is impossible to know how common this disorder is.

Below are suggested links to learn more and connect with others:

C22C Recognizes the work of Cat Eye Syndrome International, a family group based in Italy. Visit them at Cat Eye Syndrome International

What is Cat Eye Syndrome?

Video from Cat Eye Syndrome International