Cat-eye syndrome. Cat-eye syndrome is a rare disease with very varied signs and symptoms, including defects in the iris of the eye called “colobomas,” which are holes in the eye’s iris that can look like a second pupil or a black slot in the eye. The edge of the pupil (this gives the pupil an irregular shape similar to a cat’s eye), marks or depressions in the skin in the region in front of the ears, narrowing or closing of the anal opening (atresia of the anus), heart or kidney defects and intellectual disability (limitations in your mental functioning and skills such as communication, self-care, and social skills). It occurs when an individual has a small additional chromosome 22 and the two normal copies of chromosome 22. The diagnosis of cat eye syndrome is made by studying chromosomes called a karyotype that shows the presence of the additional chromosome.
Cat’s eye syndrome is a rare entity characterized by antimongoloid palpebral fissures, bilateral ocular coloboma, anorectal, cardiac, and renal malformations, preauricular pits or folds, and cognitive disability. It is characterized by significant phenotypic variability, from patients with a slightly apparent phenotype to those with severe abnormalities. The case of a two-year-old female patient with global developmental delay, brachycephaly, narrow forehead, left palpebral ptosis, bilateral congenital cataracts, bilateral preauricular pits, heart disease caused by ASD type ostium secundum, and persistent Ductus is presented. , hypoplastic left kidney and moderate hypotonia, suggestive clinical aspects of the entity in which the karyotype reports a supernumerary marker chromosome, derived from chromosome 22 (47, XX, + del (22) (per-q12)), anomaly associated with the syndrome cat’s eye. When carrying out the analysis of the mother, it is found that she is a carrier of a balanced translocation between chromosomes 11 and 22. The case is reviewed and compared with previous reports in the literature.
Cat-Eye syndrome is characterized by two main features: anal atresia and coloboma of the iris, from which the syndrome’s name derives. However, patients present a wide range of symptoms: only 41% present the classic features of anal anomalies, coloboma of the iris, and points and marks on the preauricular skin. Other more variable features include moderate hypertelorism with downward sloping palpebral fissures, heart defects, cleft palate, and urinary tract or skeletal abnormalities. Moderate intellectual deficits are present in 32% of patients. The estimated prevalence in the general population is 1 in 74,000. Five out of six cases present a karyotype showing the presence of a small supernumerary chromosome derived from the proximal part of chromosome 22. Generally, this marker is bicentric and satellite due to an inverted duplication [invdup (22)]. It is often seen in the mosaic. The presence of this extrachromosomal marker is the most relevant diagnostic criterion for the syndrome. No correlations have been identified between the severity of the intellectual deficit and the presence of malformations and the degree of mosaicism or the length of the duplications. However, patients with small markers on chromosome 22 who do not have euchromatin are not associated with phenotypes. Inverted duplication of chromosome 22 generally occurs de novo, and transmission is possible in both sexes, with a risk of transmission to offspring of approximately 50%. Prenatal diagnosis is possible by a karyotype and Fluorescent In Situ Hybridization (FISH). Surgery is required in patients with anal atresia and severe cardiac complications. A few patients with multiple severe malformations have died in childhood, but life expectancy is not significantly reduced in patients with few or moderate manifestations.
How is this pathology treated?
The truth is that there is no specific treatment for the cat-eye syndrome. However, most people who have it have a good prognosis. This depends on the severity of the disease, but many of the defects can be corrected thanks to current therapeutic options.
We must remember that this syndrome, beyond producing characteristic eyes, can affect many other parts of the body. It is a chromosomal defect that causes alterations in appearance, digestive system, and intellectual level. Therefore, its approach does not depend on a single specialty.
The signs and symptoms are highly variable, and none of the characteristics is always present in those affected. Only 41% of patients with the syndrome present a classic combination of anomalies characterized by coloboma of the iris, anal anomalies, and anomalies in the region in front of the ears (pre-atrial). Signs and symptoms can include:
• Ears with low implantation, presence of skin folds in front of the ear (90% of cases), presence of depression in the skin in the region in front of the ear • Anomalies of the eyes: coloboma of the retina (layer that covers the back of the eye that is responsible for vision), present in 50% of cases, increased space between the eyes (hypertelorism) (50% of cases), palpebral fissures sloping down (50% of cases), Iris coloboma (50% of cases), choroidal coloboma (choroid is the middle layer of the eye, which contains blood vessels and connective tissue that supplies nutrients to the inner part of the eye), abnormally very small eyes (microphthalmia) • Atresia of the anus • Genital abnormalities: abnormal communication between the genitalia and the urinary bladder or urogenital fistula (90% of cases), absence of uterus • Kidney abnormalities: small kidneys, abnormal location of the kidney (50% of cases) , kidney absent • Abnormalities of the bones: hip bone abnormalities (50% of cases), rib abnormality (50% of cases), absence of the forearm bone (radius) • Cognitive deficit (50% of cases) • Poor growth of a baby while in the womb during pregnancy (50% of cases) • Malformation of the heart (50% of cases) • Decreased muscle tone (50% of cases) • Short stature (50% of cases ) • Deafness • Absence of the forearm bone (radius) • Biliary atresia (obstruction of the drainage system (biliary tree) from the liver to the intestine) • Cleft palate (cleft palate) • Moderate intellectual disability • Intestinal malarotation (bowel malformation which is present at birth where the parts of it are located in different places than normal because there was a defect during its formation) • Very small jaw (micrognathia)