DefinitionCri du chat syndrome is a group of symptoms that result from missing a piece of chromosome number 5. The syndrome's name is based on the infant's cry, which is high-pitched and sounds like a cat.Alternative NamesChromosome 5p deletion syndrome; 5p minus syndrome; Cat cry syndromeCauses, incidence, and risk factorsCri du chat syndrome is rare. It happens when genetic information on chromosome 5 is missing. One missing piece, called TERT (telomerase reverse transcriptase) is involved in control of cell growth, and may play a role in how some of the features of this syndrome develop.Most cases are believed to occur during the development of the egg or sperm. A minority of cases result from one parent carrying a rearrangement of chromosome 5 called a translocation and passing this on