CCRRII DDUU

CCHHAATT

SYNDROMESYNDROME

by: Olivia by: Olivia GeraldGerald

12|o9|12|o9|20112011

Mrs. AbramsMrs. AbramsPeriod 3APeriod 3A

Life ScienceLife Science

What is Cri-du-Chat What is Cri-du-Chat Syndrome?Syndrome? Cri-du-chat is French for Cri-du-chat is French for

“cry of the cat”, referring to “cry of the cat”, referring to

the distinctive, high-the distinctive, high-

pitched, catlike cry made pitched, catlike cry made

by children afflicted by this by children afflicted by this

disorder.disorder. Caused by partial Caused by partial

deletion of chromosome 5p.deletion of chromosome 5p. Becomes less noticeable Becomes less noticeable

as the child gets older, as the child gets older,

making it difficult for making it difficult for

doctors to diagnose cri-du-doctors to diagnose cri-du-

chat after age two.chat after age two.

Partial deletion of the 5 pair Partial deletion of the 5 pair chromosome.chromosome.

The CauseThe Cause Cri-du-chat is caused by a deletion on the short Cri-du-chat is caused by a deletion on the short

arm of chromosome 5p – the length of the arm of chromosome 5p – the length of the deletion may vary.deletion may vary.

Multiple genes are missing as a result of this Multiple genes are missing as a result of this deletion, and each may contribute to the deletion, and each may contribute to the symptoms of the disorder.symptoms of the disorder.

One of the deleted genes known to be involved is One of the deleted genes known to be involved is HTERT (human telomerase reverse HTERT (human telomerase reverse transcriptase).transcriptase).

HTERT helps to keep the information in DNA HTERT helps to keep the information in DNA functioning properly.functioning properly.

If HTERT is damaged, mental illnesses such as If HTERT is damaged, mental illnesses such as cri-du-chat occur.cri-du-chat occur.

SYMPTOMS

Normal brain Normal brain sizesize

TOP: Normal ear position/sizeTOP: Normal ear position/sizeBOTTOM: Ear position/size with cri-du-chatBOTTOM: Ear position/size with cri-du-chat

MicrocephalyMicrocephaly Low-set earsLow-set ears

Brain size with Brain size with cri-du-chatcri-du-chat

SYMPTOMS Babies with cri-du-chat are usually small at birth, and may have Babies with cri-du-chat are usually small at birth, and may have

respiratory problems. Often, the larynx doesn’t develop correctly, respiratory problems. Often, the larynx doesn’t develop correctly, which causes the signature catlike cry.which causes the signature catlike cry.

Mental retardation: the more extensive the deletion is of Mental retardation: the more extensive the deletion is of chromosome 5p, the more severe this symptom.chromosome 5p, the more severe this symptom.

Small head (microcephaly).Small head (microcephaly). Small jaw (micrognathia).Small jaw (micrognathia). Downward slant of the eyes.Downward slant of the eyes. Wide-set eyes.Wide-set eyes. Abnormally shaped/positioned ears.Abnormally shaped/positioned ears. Webbed fingers or toes.Webbed fingers or toes. Single line in the palm of the hand (simian crease).Single line in the palm of the hand (simian crease). Hanging skin in front of the ears.Hanging skin in front of the ears. Slow or incomplete development of basic skills.Slow or incomplete development of basic skills.

Inheritance of Cri-Inheritance of Cri-du-Chatdu-Chat The deletion that causes cri-du-The deletion that causes cri-du-

chat syndrome is caused by a chat syndrome is caused by a dominant trait. dominant trait.

CTNND2 is an important gene CTNND2 is an important gene that is lost when a portion of that is lost when a portion of the 5 pair chromosome is the 5 pair chromosome is deleted.deleted.

CTNND2 gene usually makes CTNND2 gene usually makes the delta catenin protein. This the delta catenin protein. This protein works in the nervous protein works in the nervous system and helps with cell system and helps with cell movement.movement.

The loss of CTNND2 may cause The loss of CTNND2 may cause severe brain damage in some severe brain damage in some patients.patients.

CTNND2 gene under a CTNND2 gene under a microscope.microscope.

Delta Delta catenin catenin protein.protein.

Inheritance of Cri-Inheritance of Cri-du-Chatdu-Chat

a aA Aa Aa

A Aa Aa

In this example:In this example:

P GENERATION:P GENERATION:AA= dominant allele for a = dominant allele for a person person withwith cri-du-chat. cri-du-chat.aa= recessive allele for a = recessive allele for a person person withoutwithout cri-du-chat. cri-du-chat.

FF11 GENERATION: GENERATION:

All offspring have the cri-du-All offspring have the cri-du-chat syndrome because they chat syndrome because they all inherit dominant allele all inherit dominant allele AA..

Diagnosis & Diagnosis & TreatmentTreatment

Doctors most often identify cri-du-chat by looking at the Doctors most often identify cri-du-chat by looking at the patient’s symptoms. The most common symptoms are the patient’s symptoms. The most common symptoms are the infant's cat-like cry, microcephaly (small head/brain), poor infant's cat-like cry, microcephaly (small head/brain), poor muscle tone, and mental retardation.muscle tone, and mental retardation.

Another method of diagnosing cri-du-chat syndrome takes Another method of diagnosing cri-du-chat syndrome takes place while the baby is still in its mother's womb. Doctors can 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 either test a tiny sample of tissue from outside the sac where the baby develops, or they can test a sample of the amniotic the baby develops, or they can test a sample of the amniotic fluid – the protective liquid in the womb from which a baby fluid – the protective liquid in the womb from which a baby gets nourishment.gets nourishment.

There is no specific treatment available for this disorder so There is no specific treatment available for this disorder so medical care is focused on the symptoms. Physical therapy is medical care is focused on the symptoms. Physical therapy is recommended to strengthen the muscles. To increase recommended to strengthen the muscles. To increase communication skills, a speech therapist can help the child communication skills, a speech therapist can help the child learn to use sign language. learn to use sign language.

StatisticsStatistics Approximately 90% of cases of cri-du-chat Approximately 90% of cases of cri-du-chat

syndrome result from a randomly-occurring syndrome result from a randomly-occurring deletion.deletion.

The remaining 10% occurs purely by inheritance.The remaining 10% occurs purely by inheritance. Cri-du-chat syndrome occurs in an estimated 1 in Cri-du-chat syndrome occurs in an estimated 1 in

20,000 to 50,000 newborns.20,000 to 50,000 newborns. Cri-du-chat can occur in all races and in both Cri-du-chat can occur in all races and in both

genders, although there is a slight female genders, although there is a slight female predominance. The male to female ratio is 3:4.predominance. The male to female ratio is 3:4.

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

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

Interesting FactsInteresting Facts The geneticist Jerome Lejeune identified cri-du-The geneticist Jerome Lejeune identified cri-du-

chat syndrome in 1963. He also discovered the chat syndrome in 1963. He also discovered the genetic abnormality that causes Down syndrome.genetic abnormality that causes Down syndrome.

In 80% of cri-du-chat cases, the chromosome In 80% of cri-du-chat cases, the chromosome carrying the deletion comes from the father’s carrying the deletion comes from the father’s sperm rather than the mother’s eggs.sperm rather than the mother’s eggs.

If pairs of chromosomes don’t line up correctly If pairs of chromosomes don’t line up correctly during metaphase in meiosis, the structure of a during metaphase in meiosis, the structure of a chromosome can be changed. When this happens chromosome can be changed. When this happens with chromosome 5, it causes cri-du-chat.with chromosome 5, it causes cri-du-chat.

Cri-du-chat is the most common syndrome Cri-du-chat is the most common syndrome caused by deletion.caused by deletion.

BIBLIOGRAPHYBIBLIOGRAPHY 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:Encyclopedia Britannica

Webster’s Encyclopedia