C r i d u c h a t syndrome by olivia gerald 12 o9 2011 mrs abrams period 3a life science
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C R I D U C H A T SYNDROME by: Olivia Gerald 12|o9|2011 Mrs. Abrams Period 3A Life Science. What is Cri-du-Chat Syndrome?.

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C r i d u c h a t syndrome by olivia gerald 12 o9 2011 mrs abrams period 3a life science

CRI

DU

CHAT

SYNDROME

by: Olivia Gerald

12|o9|2011

Mrs. Abrams

Period 3A

Life Science


What is cri du chat syndrome

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.


The cause

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.


Symptoms

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


Symptoms1

SYMPTOMS

  • Babies with cri-du-chat are usually small at birth, and may have respiratory problems. Often, the larynx doesn’t 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.


Inheritance of cri du chat

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.


Inheritance of cri du chat1

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.


Diagnosis treatment

Diagnosis & Treatment

  • Doctors most often identify cri-du-chat by looking at the patient’s 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.


Statistics

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 3:4.

  • Approximately 30% of infants with cri-du-chat have heart defects.

  • About 1/3 of infants lose the catlike cry at age 2.


Interesting facts

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 father’s sperm rather than the mother’s eggs.

  • If pairs of chromosomes don’t 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.


Bibliography

BIBLIOGRAPHY

  • WEBSITES:

    http://medical-dictionary.thefreedictionary.com/cri+du+chat+syndrome

    http://ghr.nlm.nih.gov/condition/cri-du-chat-syndrome

    http://en.wikipedia.org/wiki/Cri_du_chat

  • BOOKS:

    EncyclopediaBritannica

    Webster’s Encyclopedia


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