Cat eye syndrome (CES) is a malformation involving an extra marker chromosome derived from Chromosome 22. CES shows characteristic features such as ocular coloboma of the iris, giving the appearance of a vertical pupil, hence the name. However, over half of the reported cases do not manifest this feature. This chromosomal abnormality usually arises spontaneously, although there are reports of intergenerational family transmission. Transmission appears to be possible through both sexes. Some reports show the parents as mosaic for the marker chromosome but without phenotypic symptoms of the syndrome.