Cat eye syndrome is the result of a genetic defect in chromosome 22, which causes an extra chromosome fragment.
This article reviews common characteristics and symptoms of cat eye syndrome. You’ll also learn the causes, diagnostic methods, treatment, and outlook for the condition.
Incidence of Cat Eye Syndrome
Cat eye syndrome affects both males and females. It occurs in about one in 50,000 to one in 150,000 individuals.
If you have CES, you’re most likely the only one in your family to have the condition. That’s because it’s usually a spontaneous chromosomal abnormality as opposed to a gene that’s inherited. However, in some cases, the abnormal chromosome can be passed down from parents to children.
Symptoms
If you or your child has CES, you may experience a wide range of symptoms. About 80% to 99% of individuals with cat eye syndrome have the following three symptoms:
Small growths of skin (tags) of the outer earsDepressions in the skin (pits) of the outer earsAn absence or obstruction of the anus (anal atresia)
Other common symptoms include:
Absence of tissue from the colored part of one or both eyes (iris coloboma) Congenital heart defects Rib abnormalities Downward slanting openings between the upper and lower eyelids Defects of the urinary tract or kidneys Short stature Cleft palate Wide-set eyes Intellectual disability
Causes
According to the National Organization for Rare Disorders (NORD), the exact cause of cat eye syndrome is not entirely understood.
In some cases, the chromosomal abnormality occurs randomly due to an error in how a parent’s reproductive cells divide. In these cases, your parent has normal chromosomes.
In other cases, it appears to result from a balanced translocation in one of your parents.
Translocations occur when portions of certain chromosomes break off and are rearranged. This results in shifting genetic material and an altered set of chromosomes.
If a chromosomal rearrangement is balanced—meaning it consists of an even exchange of genetic material with no genetic information extra or missing—it’s usually harmless to the carrier.
It’s very rare, but balanced translocation carriers may carry a slight risk of passing down a chromosomal abnormality to their children.
In other rare cases, a parent of an affected child may have the abnormal chromosome in some of their body cells. In some instances, they manifest certain mild features of the disorder.
This chromosomal abnormality may be transmitted through several generations in some families. However, the expression of associated features may be variable. As a result, only those with multiple or severe features may be identified.
Diagnosis
If you have cat eye syndrome, you were born with it. Your healthcare provider will diagnose you or your child based on your symptoms.
Genetic testing, such as a karyotype, can confirm the presence of the specific genetic defect in chromosome 22—tripling or quadrupling of parts of the chromosome—that’s associated with CES.
Treatment
CES is treated based on the symptoms you or your child has. Some children may need surgery to repair birth defects in their anus or heart.
Most people with cat eye syndrome have a normal life expectancy unless they have life-threatening physical problems such as a severe heart defect.
They can experience developmental delays, especially in activities that require muscle and mental coordination.
