CRI

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• CRI
• DU
• CHAT
• SYNDROME
• by Olivia Gerald
• 12o92011
• Mrs. Abrams
• Period 3A
• Life Science

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What is Cri-du-Chat Syndrome?

• Cri-du-chat is French for cry of the cat,
  referring to the distinctive, high-pitched,
  catlike cry made by children afflicted by this
  disorder.
• Caused by partial deletion of chromosome 5p.
• Becomes less noticeable as the child gets older,
  making it difficult for doctors to diagnose
  cri-du-chat after age two.
• Partial deletion of the 5 pair chromosome.

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The Cause

• Cri-du-chat is caused by a deletion on the short
  arm of chromosome 5p the length of the deletion
  may vary.
• Multiple genes are missing as a result of this
  deletion, and each may contribute to the symptoms
  of the disorder.
• One of the deleted genes known to be involved is
  HTERT (human telomerase reverse transcriptase).
• HTERT helps to keep the information in DNA
  functioning properly.
• If HTERT is damaged, mental illnesses such as
  cri-du-chat occur.

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SYMPTOMS
Microcephaly
Low-set ears
Brain size with cri-du-chat
Normal brain size
TOP Normal ear position/size BOTTOM Ear
position/size with cri-du-chat
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SYMPTOMS

• Babies with cri-du-chat are usually small at
  birth, and may have respiratory problems. Often,
  the larynx doesnt develop correctly, which
  causes the signature catlike cry.
• Mental retardation the more extensive the
  deletion is of chromosome 5p, the more severe
  this symptom.
• Small head (microcephaly).
• Small jaw (micrognathia).
• Downward slant of the eyes.
• Wide-set eyes.
• Abnormally shaped/positioned ears.
• Webbed fingers or toes.
• Single line in the palm of the hand (simian
  crease).
• Hanging skin in front of the ears.
• Slow or incomplete development of basic skills.

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Inheritance of Cri-du-Chat

• The deletion that causes cri-du-chat syndrome is
  caused by a dominant trait.
• CTNND2 is an important gene that is lost when a
  portion of the 5 pair chromosome is deleted.
• CTNND2 gene usually makes the delta catenin
  protein. This protein works in the nervous system
  and helps with cell movement.
• The loss of CTNND2 may cause severe brain damage
  in some patients.

CTNND2 gene under a microscope.
Delta catenin protein.
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Inheritance of Cri-du-Chat
In this example P GENERATION A dominant
allele for a person with cri-du-chat. a
recessive allele for a person without
cri-du-chat. F1 GENERATION All offspring have
the cri-du-chat syndrome because they all inherit
dominant allele A.
a a
A Aa Aa
A Aa Aa
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Diagnosis Treatment

• Doctors most often identify cri-du-chat by
  looking at the patients symptoms. The most
  common symptoms are the infant's cat-like cry,
  microcephaly (small head/brain), poor muscle
  tone, and mental retardation.
• Another method of diagnosing cri-du-chat syndrome
  takes place while the baby is still in its
  mother's womb. Doctors can either test a tiny
  sample of tissue from outside the sac where the
  baby develops, or they can test a sample of the
  amniotic fluid the protective liquid in the
  womb from which a baby gets nourishment.
• There is no specific treatment available for this
  disorder so medical care is focused on the
  symptoms. Physical therapy is recommended to
  strengthen the muscles. To increase communication
  skills, a speech therapist can help the child
  learn to use sign language.

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Statistics

• Approximately 90 of cases of cri-du-chat
  syndrome result from a randomly-occurring
  deletion.
• The remaining 10 occurs purely by inheritance.
• Cri-du-chat syndrome occurs in an estimated 1 in
  20,000 to 50,000 newborns.
• Cri-du-chat can occur in all races and in both
  genders, although there is a slight female
  predominance. The male to female ratio is 34.
• Approximately 30 of infants with cri-du-chat
  have heart defects.
• About 1/3 of infants lose the catlike cry at age
  2.

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Interesting Facts

• The geneticist Jerome Lejeune identified
  cri-du-chat syndrome in 1963. He also discovered
  the genetic abnormality that causes Down
  syndrome.
• In 80 of cri-du-chat cases, the chromosome
  carrying the deletion comes from the fathers
  sperm rather than the mothers eggs.
• If pairs of chromosomes dont line up correctly
  during metaphase in meiosis, the structure of a
  chromosome can be changed. When this happens with
  chromosome 5, it causes cri-du-chat.
• Cri-du-chat is the most common syndrome caused by
  deletion.

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BIBLIOGRAPHY

• WEBSITES
• http//medical-dictionary.thefreedictionary.com/c
  riduchatsyndrome
• http//ghr.nlm.nih.gov/condition/cri-du-chat-synd
  rome
• http//en.wikipedia.org/wiki/Cri_du_chat
• BOOKS
• Encyclopedia Britannica
• Websters Encyclopedia