Chromosome 5p deletion syndrome; 5p minus syndrome; Cri du chat syndrome
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.
Causes, incidence, and risk factors
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 (for which the syndrome was named)
- 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
Signs and tests
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.
- karyotyping (chromosome analysis) should show a missing portion of the short arm of chromosome 5. If it does not, a more detailed type of genetic test (FISH analysis) may reveal that a small piece of this chromosome is missing.
- lateral skull X-ray may show an abnormal angle to the base of the skull.
No specific treatment is available for this syndrome. The mental retardation must be addressed, and counseling is recommended for the parents.
If a child is found to have this syndrome, his parents should have genetic counseling and a karyotype test to make sure that they do not have rearranged chromosomes that predispose to the child missing part of chromosome 5.
5p- (pronounced 5p minus) Society 1-888-970-0777; http://www.fivepminus.org
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.
- inability to care for self
- inability to function in society
Calling your health care provider
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.
by David A. Scott, M.D.
All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.