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An inherited neurodevelopmental disorder with large phenotypic variability, ranging from nearly normal to severe malformations of many organs.

Schmid-Fraccaro Syndrome; Partial Tetrasomy of Chromosome 22; Coloboma-Anal Atresia Syndrome; Ocular Coloboma-Imperforate Anus Syndrome.

In 1879 the Swiss ophthalmologist O. Haab was the first to describe a syndrome of anal atresia combined with coloboma. However, the extra chromosome 22 responsible for the syndrome was detected by W. Schmid from Zurich, Switzerland, and M. Fraccaro from Pavia, Italy, who named it cat eye syndrome (CES) because of the inferior coloboma (resulting in a vertical, cat-like pupil) and the downslanting palpebral fissures, although more than 50% of patients have no signs of coloboma.

In Switzerland, the incidence has been estimated to be 1 in 50,000-150,000 live births. This most likely is representative of other countries, as no racial predilection has been reported.

Autosomal dominant. Trisomy or tetrasomy 22 (22q11). The additional chromosome 22 generally arises de novo from one of the parents.

Not fully described.

Clinical features (mainly coloboma, anal atresia, and preauricular pits/tags) may lead to the diagnosis. However, because of the wide clinical spectrum of this disorder, the final diagnosis is made by fluorescent in situ hybridization (FISH), which shows the presence of an extra marker chromosome derived from chromosome 22 (partial extra chromosome or duplication) containing two copies of the CES region.

Clinical variability is remarkable, with the spectrum of features ranging from only minimally affected individuals to those with the full picture of malformations and lethal outcome. Minimally affected patients may show only downslanting palpebral fissures and preauricular pits or tags. However, CES usually is characterized by the combination of coloboma of the iris (unior bilateral), total or partial coloboma of the choroidea and/or optic nerve, microphthalmia (most often unilateral), downslanting palpebral fissures, preauricular tags and/or pits, and anal atresia with rectovesical, rectovaginal, or rectovulvar fistulas in females and rectovesical, rectourethral, or rectoperineal fistulas in males. Other frequently encountered anomalies include renal anomalies (absence of one or both kidneys, supranumeric kidneys, renal hypoplasia, hydronephrosis) and congenital cardiovascular malformations (tetralogy of Fallot, total anomalous pulmonary venous drainage, persistent left superior vena cava, Eisenmenger complex) in more than one third of patients. Additional craniofacial stigmata may include aniridia, cataract, hypertelorism, strabismus, inner epicanthic folds, flat nasal bridge, choanal atresia, cleft lip and palate, mandibular hypoplasia, additional ear malformations (reduction of the auricles to several tags only and atresia of the external auditory canal), and hypothalamic growth hormone deficiency (without severe growth retardation). Skeletal anomalies may present as absence or synostosis of ribs, scoliosis, vertebral fusions, and limb malformations (radial aplasia, duplication of the hallux, absent toes and sirenomelia). Visceral anomalies include pulmonary segmentation defects, intestinal malrotation, biliary atresia, Hirschsprung disease, Meckel diverticulum, umbilical hernia, uterus hypoplasia and vaginal atresia in girls, and hypospadia in boys. Cases of CES in combination with spina bifida or myelomeningocele have been reported. ...

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