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C R I D U C H A T SYNDROME by: Olivia Gerald 12|o9|2011 Mrs. Abrams

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

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  1. CRI DU CHAT SYNDROME by: Olivia Gerald 12|o9|2011 Mrs. Abrams Period 3A Life Science

  2. 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.

  3. 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.

  4. 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

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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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