Phenotypic variability of cat-eye syndrome

Cat-Eye syndrome (CES) is a disorder with a variable pattern of multiple co ngenital anomalies of which coloboma of the iris and anal atresia are the b est known. CES is cyogenetically characterised by the presence of an extra bisatellited marker chromosome, which represents an inverted dicentric dupl ication of a part of chromosome 22 (inv dup(22)). We report on three CES-patients who carry an inv dup(22) diagnosed with FIS H studies. They show remarkable phenotypic variability The cause of this va riability is unknown. Furthermore, we review clinical features of 71 report ed patients. Only 41% of the CES-patients have the combination of iris colo boma, anal anomalies and pre-auricular anomalies. Therefore, almost 60% of the CES-patients are hard to recognize by their phenotype alone. Mild to mo derate mental retardation was found in 32% (16/50) of the cases. Mental ret ardation occurs more frequently in male CES-patients. There is no apparent phenotypic difference between mentally retarded and mentally normal CES-pat ients.