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Cri-du-chat Syndrome
Sunday, 20 July 2003
Monday, 18 July 2005
Cat Cry Syndrome, Chromosome 5p deletion syndrome, 5p minus syndrome

What

Cri-du-chat (“cry of the cat” in French) syndrome describes a group of symptoms caused by a particular genetic anomaly (chromosomal deletion), with the most notable symptoms being mental retardation and the characteristic high-pitched cry of an affected newborn.

Who

The syndrome occurs in about 1 out of every 20,000 to 50,000 births, and is diagnosed in infancy. There is no racial preference, but girls are more often affected with a female to male ratio of 1.4 to 1.

Signs and Symptoms

The following may be seen:

  • Distinctive high-pitched cry, which may eventually disappear after 2 years of age.
  • Low birth weight and decreased muscle tone
  • Poor sucking and swallowing
  • Small head, round face with full cheeks, flat nasal bridge, down-turned mouth, small jaw, and low-set ears
  • Eyes can be wide-set, downward-slanting, and crossed, with epicanthal folds (redundant folds of the eyelid)
  • Short fingers and single palmar creases
  • May also have heart defects
  • Less frequently seen are defects of the extremities, lip and palate, and kidney malformations Additional findings later in childhood and adolescence include:
  • Severe mental retardation and global developmental delay
  • Failure to thrive
  • Increased muscle tone
  • Premature graying of the hair
  • Small, narrow, asymmetric face with dropped jaw and open mouth due to weak facial muscles, short philtrum (midline groove from the bottom of the nose to the upper lip), and teeth that are not aligned properly
  • Scoliosis (improper curvature of the spine)
  • Short fingers
  • Recurrent upper respiratory infections, ear infections, severe constipation
  • Hyperactivity, aggressive behavior, tantrums, repetitive and self-injurious behaviors, hypersensitivity to sound, clumsiness, obsessive attachments to objects
  • Small testicles

.

Possible Causes

The syndrome is a result of deletion of part of the short arm (called the p arm) of chromosome 5, and studies have shown two regions where the critical genetic material is located. In 80-85% of cases, this deletion occurs spontaneously soon after fertilization of the egg by a sperm, and is in other words a new mutation. 80% of these deletions occur on the chromosome donated by the father, but no specific cause has been found. In the remaining 10-15% of all cases, the deletion results from a balanced translocation in one of the parents. A balanced translocation means that the normal number of chromosomes are present, but that 2 parts of different chromosomes have switched with each other; the carrier is usually not affected, but when they try to have children, the resulting products of fertilization may end up with a part of the genetic material that is duplicated and another part that is completely missing (see http://www.conceivingconcepts.com/learning/articles/balanced.html for a more in-depth explanation). In these children, there is not only a deletion of chromosome 5p, there is also an extra copy of genetic material from another part of the genome, which can result in more severe signs and symptoms in addition to the above.

Diagnosis

In addition to the recognition of the characteristic physical and historical features, genetic studies can be done both before and after birth to confirm the diagnosis. Prenatal diagnosis is possible using procedures that obtain fetal cells, such as chorionic villus sampling or amniocentesis. After birth, the studies are performed on blood obtained from the baby. Conventional and higher-resolution cytogenetic studies (taking a picture of an individual’s chromosomes and examining for abnormalities) will look for the deletion on chromosome 5p. However, they miss very small deletions, in which case a technique called fluorescence in situ hybridization (FISH) is helpful. Using a specific probe designed to compliment known sequences in the critical regions of the chromosome, scientists can essentially scan for those parts. If two signals fluoresce, then there is no deletion, but if only one lights up, that indicates the critical region is missing on the other chromosome and confirms the diagnosis. No other studies are needed for diagnosis, however the child may undergo imaging of the brain and skeleton, ultrasound of the heart, swallowing studies, and developmental testing to characterize and manage their symptoms individually.

Treatment

There is no specific treatment for the disease, and care is directed at the affected individual’s symptoms and needs. These children will require frequent doctors’ appointments to manage feeding problems, frequent infections, constipation, and any heart defects that may need intervention. Dental referral should be made as soon as tooth misalignment is noticed. Children should also be referred early to a developmental specialist or center that can provide occupational, physical, and speech therapy. As they grow older, they will need special education services. Some parents may try behavioral modification programs, or even medication, to control the child’s hyperactivity and obsessive behaviors. Referral to a genetic specialist and genetic counseling services are important components of assisting the family with an affected child. Females with cri-du-chat are able to give birth, with a 50% chance of having an affected child with each pregnancy. For the parents of an affected child, the risk of having another child with the syndrome is very low unless either the mother or father is a carrier for a balanced translocation, as described above. In these cases, the recurrence risk is significantly higher and will depend on the structure of the translocation and how it divides after fertilization.

Prognosis

The prognosis for children with cri-du-chat syndrome is highly variable, though most will have normal lifespans unless they have significant heart defects. Their social skills usually do not advance past those of a normal 6-year-old child, and their language skills may be further behind. By the time they are adolescents, some are able to walk, communicate either verbally or with sign language, and clean and feed themselves.

Connect with other parents

In the spirit of community and support, Madisons Foundation offers the unique service of connecting parents of children with rare diseases. If you would like to be connected to other parents of children with this disease, please fill out this brief form.

Weblinks

The 5p- Association
An association dedicated to providing information and support to those affected by this disease. Well-designed site that also has links to other resources that could be helpful for families.

Chromosome Deletion Outreach, Inc.
Founded by parents of children with chromosomal disorders, this non-profit group provides a network of support, including message boards, articles, and newsletters.

The Cri-du-chat Syndrome Support Group
A nice website aimed at providing support for families affected by this disease, based out of Britain. There is a photoboard, messageboard and chat room among other support options. Cri-du-chat Support Group of Australia http://www.criduchat.asn.au/ Useful website with parental support links.

The Family Village
Central resource to other useful links.

National Organization for Rare Disorders
A fee is charged for some useful information from a reliable source.

Google Search for Cri-du-chat Syndrome

References and Sources

• Chen H (2005). eMedicine: Cri-du-chat syndrome. www.emedicine.com/ped/topic504.htm • Stewart DR (2003). MedlinePlus Medical Encyclopedia: Cri du chat syndrome. www.nlm.nih.gov/medlineplus/ency/article/001593.htm • OMIM www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=123450