Cri du chat syndrome is a group of symptoms that result from missing a piece of chromosome number 5. The syndrome’s name is based on the infant’s cry, which is high-pitched and sounds like a cat.

The cri du chat syndrome is caused by the deletion of information on chromosome 5. It is likely that multiple genes on chromosome 5 are deleted. One deleted gene, called TERT (telomerase reverse transcriptase) is involved in control of cell growth, and may play a role in how some of the features of cri cu chat develop.

The cause of this rare chromosomal deletion is not known, but it is expected that the majority of cases are due to spontaneous loss of a piece of chromosome 5 during development of an egg or sperm. A minority of cases result from one parent carrying a rearrangement of chromosome 5 called a translocation.

Between 1 in 20,000 and 1 in 50,000 babies are affected. This disease may account for up to 1% of individuals with severe mental retardation. Infants with cri du chat syndrome commonly have a distinctive cat-like cry. They also have an extensive grouping of abnormalities, with severe mental retardation being the most important.

• High-pitched cry sounds like a cat
• Low birth weight and slow growth
• Small head (microcephaly )
• Wide-set eyes (hypertelorism)
• Downward slant to the eyes (palpebral fissures)
• Small jaw (micrognathia )
• Low-set ears (may be malformed)
• Skin tags just in front of the ear
• Partial webbing or fusing of fingers or toes
• Single line in the palm of the hand (simian crease )
• Mental retardation
• Slow or incomplete development of motor skills

In addition to the other findings (listed with Symptoms), physical examination may show:

• Inguinal hernia
• Diastasis recti (separated abdominal muscles)
• Low muscle tone
• Epicanthal folds, an extra fold of skin over the inner corner of the eye
• Incompletely or abnormally folded external ears
• A missing portion of the short arm of chromosome 5 seen on chromosome analysis (if not, a more detailed type of genetic test called FISH analysis may reveal that a small piece of this chromosome is missing)
• An abnormal angle to the base of the skull seen on lateral skull x-ray

No specific treatment is available for this syndrome. The mental retardation must be addressed, and counseling is recommended for the parents.

Parents of a child with this syndrome should have genetic counseling and a karyotype test to determine if one parent has a rearrangement of chromosome 5.

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The outcome varies but mental retardation is the norm. Half of children learn sufficient verbal skills to communicate. The cat-like cry becomes less apparent with time.

Complications depend on the extent of mental retardation and physical abnormalities. Complications may include:

• Inability to care for self
• Inability to function in society

This is a diagnosis that is generally made in the hospital at birth. Your health care provider will discuss the findings with you. On discharge, it's important to maintain regular contact with your health care provider and other care givers. Genetic counseling and testing is recommended for all families with a history of this syndrome.

The exact cause of this genetic disorder is unknown, therefore prevention is also unknown.