Cat eye syndrome is a rare genetic disease that is characterized by disorders of the development of the eyes, the facial skeleton, and various anomalies of internal organs. Pathology occurs when there is a so-called additional marker chromosome in the human karyotype. The syndrome is manifested by a pathognomonic triad of signs: coloboma of the eye iris, atresia of the anus, deformities of the auricles. Defects in the formation of the heart, kidneys, liver are often observed, some patients also have mental retardation. Diagnosis of the syndrome is based on cytogenetic research. Symptomatic treatment: cardiac surgery, plastic correction of facial defects.
Q92.8 Other specified trisomies and partial autosomal trisomies
Cat eye syndrome (CES) has a synonymous name Schmid-Frakkaro syndrome. Its clinical signs were first described by the Swedish ophthalmologist Otto Haab in 1898, and the genetic basis was established only in 1965. Pathology is extremely rare: 1 case per 50-150 thousand live-born newborns. However, the problem does not lose its relevance in modern genetics, since specialists are required to detect the disease as early as possible, and to select an adequate comprehensive treatment.
The development of cat eye syndrome is associated with the presence of an additional marker chromosome in the patient’s karyotype, which is formed from the genetic material of chromosome 22 by inverted duplication of the 22pter → q11 site. As a result, there is a partial tetrasomy on the 22nd chromosome. Mosaic forms of the syndrome are also not excluded. Mutation occurs spontaneously during early embryogenesis. Specific provoking factors have not yet been established.
Chromosomal abnormality is associated with disorders of ontogenesis in the embryonic period, when all organs and tissues are laid. The formation of a coloboma is most likely due to the incorrect closure of the slit of the eyeglass, as a result of which the shape of the iris of the eye is disturbed. The formation of heart defects occurs at 3-8 weeks of intrauterine development under the influence of genetic mutations.
Typical manifestations of cat eye syndrome are determined immediately after birth. The infant has specific facial anomalies: brachycephalic head shape, protruding forehead, underdevelopment of the jaws, accompanied by difficulties in opening the mouth. Cleft soft and hard palate, drooping eyelids, asymmetry of facial features are also characteristic. In most patients, there is a deformation of the auricle, the appearance of periauricular processes.
A pathognomonic sign of the syndrome is a bilateral coloboma — a defect of the iris, which gives a resemblance to a cat eye. Atresia of the anus also occurs. Of the somatic defects, anomalies of the heart are common: pulmonary artery atresia, tetrad of Fallot, defects of the atrial or interventricular septum. Possible lesions of the gastrointestinal tract (fistulas, diverticula, megacolon), urogenital tract (kidney hypoplasia, hydronephrosis).
Severe chromosomal abnormalities in cat eye disease are associated with a delay in the physical development of the child. Such patients usually have low growth, which is caused by insufficient production of somatotropin. Disorders of the rate of puberty are common in patients of both sexes, the formation of primary hypogonadism is possible. In early childhood, frequent infections associated with insufficient immunity are of concern.
About 7% of embryos with gross defects die in the first months of intrauterine life. At the same time, the mother has a miscarriage. Cat eye syndrome, which is combined with multiple anomalies, has a high mortality rate in the postnatal period. The main causes of death are cardiac disorders, bacterial infections that have joined.
Defects in appearance, which are caused by coloboma and anomalies of the facial structure, often make it difficult for a child to socialize in a team, make him an object of ridicule by his peers. Against this background, depression, affective states, psychopathic disorders may occur. Cases of excessive aggression of patients directed at others are described. About 32% of patients suffer from mental retardation of varying severity.
The examination of the child is carried out by a pediatrician-neonatologist, according to the indications, a neurologist, cardiologist, geneticist are involved in the examination. It is possible to suspect the presence of cat eye syndrome by the pathognomonic triad: anal atresia, iris coloboma, ear deformities, which 41% of patients have. Advanced diagnostics includes laboratory and instrumental techniques:
- Cytogenetic study. To confirm the diagnosis, fluorescent hybridization with a DNA probe is necessary, with the help of which a characteristic chromosomal mutation is detected. A 72-hour culture of peripheral blood lymphocytes is used for the study.
- Echocardiography. Ultrasound of the heart with Dopplerography is the safest method of assessing the structural and functional features of the organ and visualization of congenital malformations. Angiography, CT or MRI of the heart are recommended to clarify the diagnosis.
- CT scan of the facial skull. The study is carried out for detailed visualization of anomalies of bone structures, determination of their depth and localization. When planning orthodontic care, the technique is supplemented by telerentgenography.
- Additional methods. Ophthalmoscopy is performed to diagnose disorders of the eye apparatus. If gastrointestinal malformations are suspected, an overview radiography or CT scan of the abdominal organs is prescribed. To identify problems with the urinary system, ultrasound of the kidneys and excretory urography are used.
There is no specific therapy for cat eye syndrome. Patients need the help of different specialists in accordance with the nature and severity of clinical manifestations. Treatment is aimed at preventing complications, improving the quality of life of the patient, restoring the normal phenotype. The following areas of medical care are distinguished:
- Proper care. Infants need correction of feeding, selection of orthodontic nipples, since breastfeeding is difficult due to the inability to fully open the mouth.
- Cardiac surgical correction. For heart defects accompanied by circulatory disorders, surgical intervention is recommended in the first or second year of a child’s life, and critical disorders are operated at the age of 3-6 months.
- Plastic surgery. To close the defects of the palate, eliminate facial asymmetry and other unaesthetic features of appearance, the help of plastic and maxillofacial surgeons is required. The terms of operations are set individually.
- Rehabilitation. For the correct development of speech, taking into account the anomalies of the structure of the articulatory apparatus, classes with a speech therapist are shown. In some cases, orthodontic correction is prescribed.
Prognosis and prevention
Patients with mild phenotypic manifestations of cat cry syndrome and the absence of severe somatic abnormalities have a normal life expectancy. A less favorable prognosis for cardiac defects, which are accompanied by heart failure, delayed physical development. Prevention of the syndrome includes medical and genetic counseling, prenatal diagnosis for couples with burdened heredity.