Cri du ChatChromosome 5P Deletion Syndrome

Aravind Nair

Genetic Cause of Cri Du Chat

Cri Du Chat is a genetic disorder caused by a deletion on the short arm of Chromosome 5

Various genes are deleted and each contributes towards the disorder

TERT (Telomerase Reverse Transcriptase) – important during cell division because it helps keep the tips of chromosomes (telomeres) intact

Inheritance

There are two types of genetic disorders: hereditary and non-hereditary

Hereditary disorders are those that are passed from parents to their offspring

Non-hereditary disorders CANNOT be passed from parents to offspring and are RANDOM occurrences

Cri Du Chat is a NON-HEREDITARY disorder caused by a random deletion in a section of Chromosome 5 and has nothing to do with the genetic makeup of the parents

However, it is important to note that in about 80% of the cases of Cri du Chat, the deleted Chromosome 5 is paternal

Symptoms Small at birth

Larynx does not develop correctly – causes the “cat-like cry” Small head Round Face Small Chin Wide Eyes Folds over skin/eyes Small bridge of nose Various internal problems

Heart defects Muscular/skeletal problems Hearing/Sight problems

Walking/Talking issues Behavioral problems (aggression, hyperactivity) Mental Retardation

Risk Factors

Very Rare disorder: Affects estimated 1 in 20,000 to 50,000 births

Found in all ethnic backgrounds

Most common in females

Most cases seem to occur in development of egg/sperm

Most cases result when one parent carries a translocation of chromosome 5

Translocation: Rearrangement of parts between the chromosomes that are not members of the same pair

Can be balanced: Fully functional which causes no physical differences

Treatments/Testing

Symptoms may be individually treated, but there is no cure for the disorder

If there are no major organ defects and critical medical conditions, life expectancy is normal

Speech/Language Therapy

Doctors usually diagnose Cri du Chat by the “cat cry”

New tests for diagnosing Cri du Chat in the womb

Sample of tissue from outside the sac where the baby develops (chorionic villus sampling [CVS])

Sample of amniotic fluid that surrounds the baby (amniocentesis)

Sources

http://learn.genetics.utah.edu/content/disorders/chromosomal/cdc/

http://www.genome.gov/19517558

http://www.healthline.com/health/cri-du-chat-syndrome#Causes2