February 9, 2015
Cri-du-chat syndrome gets its name from the French language meaning â€œcry of the cat.â€ It is called this because one of the symptoms is a high-pitched signature scream or cry that comes from infants with this syndrome. The cry comes from abnormal larynx development. Every chromosome has a p arm and a q arm that are attached at the centromere of the chromosome. P is the shorter arm and q is the longer arm. â€œCri-du-chat syndrome is caused by a deletion of the end of the short (p) arm of chromosome 5.â€ (Genetics Home Reference) Most of the critical information deleted that is responsible for this syndrome is located in band 5p15.2. The abnormality is written as 5p-. The affect of the deletion means that there are multiple ...view middle of the document...
â€ (Learn.Genetics) Once one of the gametes with a DNA break is fertilized, that child will develop Cri-du-chat syndrome. Chromosome 5 has about 900 genes, which are the instructions to build proteins. With cri-du-chat syndrome, and many other syndromes, the deletion of part of the chromosome would be like removing a segment of the instructions (genes). Through the development of babies without certain parts of instruction, abnormalities will occur.
The symptoms vary depending on how much of the chromosome is actually missing. The most common recorded symptoms are being small at birth, possible respiratory problems, and problems with larynx development. People with the syndromes may also have recognizable differences such as, a small head, round face, small chin, eyes far apart, a small bridge of the nose, and fold of skin over the eyes. Depending on how much of the DNA was deleted, people may also have differences that go on internally. A small amount of children have heart defects, muscular or skeletal problems, hearing or sight problems, or poor muscle tone. With time people can have difficulty walking and talking, they may experience behavioral problems as well. There is usually an acute intellectual disability as well. The life expectancy is normal.
Cri-du-chat affects between 1 in 20,000 and 1 in 50,000 babies. More people are starting to be diagnosed as research and studies further. In around 80% of the cases, the abnormal chromosome is carried with the sperm rather than with egg.
"Genetic Science Learning Center, University of Utah, http://learn.genetics.utah.edu."
National Library of Medicine (US). Genetics Home Reference [Internet]. Bethesda (MD): The Library; 2015 February 2. Cri-du-chat syndrome; [reviewed 2014 February; cited 2015 February 9]; [about 4 screens]. Available from: http://ghr.nlm.nih.gov/condition/cri-du-chat-syndrome