Cat eye syndrome

Overview

Cat eye syndrome (CES) is a rare chromosomal disorder named for a distinctive eye abnormality seen in some cases—coloboma of the iris—which gives the eye a cat-like appearance. However, not all individuals with CES have this feature. The condition is characterized by a wide range of signs and symptoms, including ocular defects, anal atresia, ear anomalies, heart defects, kidney malformations, and developmental delays. The severity and specific features can vary greatly among individuals, even within the same family.

Causes

Cat eye syndrome is caused by the presence of an extra small chromosome, known as a marker chromosome, which includes duplicated genetic material from chromosome 22. This extra chromosome is often made up of two copies of a portion of the long arm (q arm) and short arm (p arm) of chromosome 22, including a region known as 22q11. This genetic duplication occurs sporadically (de novo) in most cases, meaning it is not inherited from the parents. However, rare familial cases with inherited marker chromosomes have been reported.

Symptoms

The symptoms of Cat eye syndrome can range from mild to severe and may involve multiple organ systems. Common features include:

• Iris coloboma: A key feature in some cases, where the iris is not fully formed, giving a “cat-eye” appearance

• Anal atresia: Absence or blockage of the anal opening

• Preauricular pits or tags: Skin tags or small holes near the ears

• Ear malformations: Including low-set or abnormally shaped ears

• Heart defects: Such as atrial septal defect (ASD) or total anomalous pulmonary venous return (TAPVR)

• Kidney abnormalities: Including malformations or absent kidneys

• Facial features: Wide-set eyes (hypertelorism), small jaw, or cleft palate

• Growth and developmental delays: Varying degrees of intellectual disability and learning difficulties

• Hernias or other gastrointestinal issues

Diagnosis

Diagnosis of Cat eye syndrome is typically confirmed through genetic testing. Key diagnostic methods include:

• Chromosomal analysis (karyotyping): Detects the presence of the extra marker chromosome derived from chromosome 22

• Fluorescence in situ hybridization (FISH): Used to specifically identify duplicated material from 22q11

• Comparative genomic hybridization (CGH) or microarray: Provides a more detailed look at chromosomal duplications or deletions

• Physical examination: Clinical assessment based on the presence of characteristic features

• Imaging studies: Echocardiogram, abdominal ultrasound, or brain imaging may be used to assess organ involvement

Treatment

There is no cure for Cat eye syndrome, and treatment is supportive and tailored to the individual’s specific symptoms and needs. A multidisciplinary team approach is often necessary. Management may include:

• Surgical correction: For anal atresia, heart defects, or kidney malformations

• Ophthalmologic care: Management of eye abnormalities, including possible surgery for colobomas

• Hearing aids or surgical interventions: For ear malformations or hearing loss

• Speech, physical, and occupational therapy: To support developmental progress

• Special education services: For intellectual or learning disabilities

• Regular monitoring: Ongoing follow-up with cardiology, nephrology, genetics, and developmental specialists

Prognosis

The prognosis for individuals with Cat eye syndrome depends on the severity and range of symptoms. Some individuals may have only mild physical differences and normal intelligence, while others may face significant medical challenges and developmental delays. With appropriate medical care, early intervention, and supportive therapies, many individuals with CES can lead fulfilling lives. Regular monitoring and individualized care plans are essential to manage complications and promote the best possible outcomes.