[3] The prognosis for patients with CES varies depending on the severity of the condition and their associated signs and symptoms, especially when heart or kidney abnormalities are seen.

It may be hereditary and parents may be mosaic for the marker chromosome, but show no phenotypic symptoms of the syndrome.

[7] This sSMC may be small, large, or ring-shaped, and typically includes 2 Mb, i.e. 2 million DNA base pairs, termed the CES critical region, located on its q arm(s) between its band 11 and terminus (area notated as 22pter→q11)(also see small supernumerary marker chromosomes in cat eye syndrome).

[9] An ultrasound exam may be used by a doctor to detect a birth defect that might be CES before a baby is born.

These tests may include:[medical citation needed] The abnormalities common to CES were first cataloged in 1899,[10] and described in association with a small marker chromosome in 1965.