Cat Eye Synrome is a very rare malformation involving Chromosome 22. The short arm (p) and a small section of the long arm (q) are present three (trisomic) or four times (tetrasomic) instead of the usual two times. The additional chromosome 22 usually arises spontaneously (de novo), though it has been reported to have been passed down in families, and some reports show the parents as mosaic for the marker chromosome but who show no phenotypic (outer) symptoms of the syndrome.