A girl afflicted with Cri du Chat Syndrome at ages six (left) and sixteen (right).

Cri du Chat Syndrome (CCS) is a group of symptoms resulting from a deletion of variable size on the arm of chromosome five. The syndrome gets its name from the sound of an affected infant's cat-like cry. First discovered in 1963 by Dr. Jerome Lejeune, CCS is caused by a random chromosomal mutation in the father's sperm 80 percent of the time. It is more prevalent in females by a ratio of 4:3 and is found in all ethnicities. This syndrome occurs in an estimated 1 in 20,000 to 50,000 newborns.

 High-pitched cry that sounds like a cat (about 1/3 of children lose the cry by the age of 2)  Downward slant to the eyes  Low birth weight and slow growth  Low-set or abnormally shaped ears  Mental retardation  Partial webbing  Simian crease (single line in the palm of the hand)  Slow or incomplete development of motor skills  Small head and jaw

Mental retardation is very common, but each case varies. About half of those with CCS are able to learn enough verbal skills to communicate with others, and the cat-like cry becomes less apparent over time, if not completely gone.

As shown above, CCS results from a deletion of the end of chromosome number five. Most cases of the syndrome are not inherited as the deletion is usually a random event during the formation of reproductive cells or early development. Affected individuals usually have no history of the syndrome in the family. About 10 percent of people with CCS inherit the abnormality. This is when an unaffected parent carries a balanced translocation, a chromosomal rearrangement where no genetic material is neither gained nor lost.

There is no specific treatment available for CCS. Parents should have genetic counseling and a karyotype test to determine if one parent has a rearrangement of chromosome number five. Unfortunately, there is no known prevention for CCS.