Definition
Cri du chat (a French phrase that means "cry of the cat")
syndrome is a group of symptoms that result when a piece of chromosomal
material is missing (deleted) from a particular region on chromosome 5.
Children born with this chromosomal deletion have a characteristic mewing
cat-like cry as infants that is thought to be caused by abnormal
development of the larynx (organ in the throat responsible for voice
production). They also have unusual facial features, poor muscle tone (
hypotonia
), small head size (microcephaly), and
mental retardation
.
Description
Jerome Lejeune first described cri du chat syndrome in 1963. Cri du chat
syndrome is also called 5p minus syndrome or chromosome 5p deletion
syndrome because it is caused by a deletion, or removal, of genetic
material from chromosome 5. The deletion that causes cri du chat syndrome
occurs on the short or p arm of chromosome 5. This deleted genetic
material is vital for normal development. Absence of this material results
in the features associated with cri du chat syndrome.
A high-pitched mewing cry during infancy is a classic feature of cri du
chat. Infants with cri du chat also typically have low birth weight, slow
growth, a small head (microcephaly), and poor muscle tone (hypotonia).
Infants with cri du chat may also have congenital heart defects, language
difficulties, delayed motor skill development,
scoliosis
, and varying degrees of mental retardation. Behavioral problems such as
hyperactivity may also develop as the child matures.
Demographics
It has been estimated that cri du chat syndrome occurs in one of every
50,000 live births. According to the 5p minus Society, approximately 50 to
60 children are born with cri du chat syndrome in the United States each
year. The syndrome can occur in all races and in both sexes.
Causes and symptoms
Cri du chat is the result of a chromosome abnormality—a deleted
piece of chromosomal material on chromosome 5. In 90 percent of children
with cri du chat syndrome, the deletion is sporadic. This means that it
happens randomly and is not hereditary. If a child has cri du chat due to
a sporadic deletion, the chance the parents could have another child with
cri du chat is 1 percent. In approximately 10 percent of children with cri
du chat, there is a hereditary chromosomal rearrangement that causes the
deletion. If a parent has this rearrangement, the risk for their having a
child with cri du chat is greater than 1 percent.
An abnormal larynx causes the unusual cat-like cry made by infants that is
a hallmark feature of the syndrome. As children with cri du chat get
older, the cat-like cry becomes less noticeable. This can make the
diagnosis more difficult in older children. In addition to the catlike
cry, individuals with cri du chat also have unusual facial features. These
facial differences can be very subtle or more obvious. Microcephaly (small
head size) is common. During infancy many children with cri du chat do not
gain weight or grow normally. Approximately 30 percent of infants with cri
du chat have a congenital heart defect. Hypotonia (poor muscle tone) is
also common, leading to problems with eating and slow, but normal
development. Mental retardation is present in all children with cri du
chat, but the degree of mental retardation varies between children.
A doctor should be consulted if a child exhibits symptoms typical of cri
du chat syndrome.
Diagnosis
During infancy, the diagnosis of cri du chat syndrome is strongly
suspected if the characteristic cat-like cry is heard. If a child has this
unusual cry or other features seen in cri du chat syndrome, chromosome
testing should be performed. Chromosome analysis provides the definitive
diagnosis of cri du chat syndrome and can be performed from a blood test.
Chromosome analysis, also called karyotyping, involves staining the
chromosomes and examining them under a microscope. In some cases the
deletion of material from chromosome 5 can be easily seen. In other cases,
further testing must be performed. Fluorescence in-situ hybridization
(FISH) is a special technique that detects very small deletions. The
majority of the deletions that cause cri du chat syndrome can be
identified using the FISH technique.
Treatment
As of 2004, there is no cure for cri du chat syndrome. Treatment consists
of supportive care and developmental therapy.
Prognosis
Individuals with cri du chat have a 10 percent mortality during infancy
due to complications associated with congenital heart defects, hypotonia,
and feeding difficulties. Once these problems are controlled, most
individuals with cri du chat syndrome have a normal lifespan. The extent
of mental retardation and other symptoms depends on the site of the
chromosomal deletions, with larger deletions resulting in more serious
symptoms. With extensive early intervention and special schooling, many
cri du chat children can develop adequate social, motor, and language
skills.
Prevention
As of 2004, cri du chat syndrome had no known prevention.
Parental concerns
Cri du chat syndrome can be detected before birth if the mother undergoes
amniocentesis
testing or chorionic villus sampling (CVS). This testing would only be
recommended if the mother or father is known to have a chromosome
rearrangement, or if they already have a child with cri du chat syndrome.
Families may wish to seek counseling regarding the effects of the syndrome
on relationships within the
family
. Many people respond with guilt,
fear
, or blame when a genetic disorder is diagnosed in the family, or they may
overprotect the affected member. Support groups are often good sources of
information about cri du chat syndrome; they can offer helpful suggestions
about living with it as well as emotional support.
ResourcesBooks
Key, Doneen.
Do You Want to Take Her Home?: Trials and Tribulations of Living Life as
a Handicapped Person Due to Multiple Birth Defects.
Lancaster, CA: Empire Publishing, 2001.
Moore, Keith L., et al.
Before We Are Born: Essentials of Embryology and Birth Defects.
Kent, UK: Elsevier—Health Sciences Division, 2002.
5p- Society.
7108 Katella Ave. #502, Stanton, CA 90680. Web Site:
http://www.fivepminus.org.
Alliance of Genetic Support Groups.
4301 Connecticut Ave. NW, Suite 404, Washington, DC 20008. Web site:
http://www.geneticalliance.org.
Cri du Chat Society.
Department of Human Genetics, Box 33, MCV Station, Richmond VA 23298.
Telephone: 804/786-9632.
Cri du Chat Syndrome Support Group.
Web site: http://www.cridchat.u-net.com.
National Organization for Rare Disorders (NORD).
PO Box 8923, New Fairfield, CT 06812-8923. Web site:
http://www.rarediseases.org.
"Cri du chat syndrome."
Medline Plus.
Available online at
http://www.nlm.nih.gov/medlineplus/ency/article/001593.htm
(accessed November 16, 2004).
Judith Sims Holly Ann Ishmael, M.S.
