Cat Eye Syndrome is the more common name for a condition
involving a partial trisomy or tetrasomy of part of chromosome
22. A small extra chromosome (humans normally have only 2) made
up of the top half of chromosome 22 – the “p” arm, as well as
the portion of the long arm of chromosome 22 down to the
breakpoint q11.2, is found to be present either three times
(trisomy) or four times (tetrasomy ).
Cat Eye Syndrome is also known in the literature as
Schmid-Fraccaro Syndrome, Partial Tetrasomy 22, or Inv
Dup(22)(q11) (Inverted Duplication).It is often referred to as Cat Eye Syndrome as some of
the people affected may have coloboma of the iris – which make
their eyes appear to look like cat’s eyes. This feature however,
is only reported in about half of the known cases. The earliest
reports stem back over 100 years ago, but the first association
Clinically, this is one of the more variable syndromes. People
who have Cat Eye Syndrome can be anywhere from normal to
suffering from severe malformations.
This has proven true
of the people who have joined our group, who have this
Some of the features seen in people with CES include coloboma of
the iris, anal atresia, ear tags and/or ear pits, heart defects,
and kidney malformations, but because of the variability, there
have been reports of malformations affecting almost every organ.
Cognitively, people with CES can be considered either normal
intelligence, or have varying degrees of mental delay, although
it is rare to see severe mental impairment in this condition.
The condition usually arises spontaneously, but our group does
have some members who have CES and have passed it on to their
One of the best write ups on the condition is found at the