Cri du chat syndrome, like Wolf-Hirschhorn syndrome, does not strictly belong to the group of microdeletion syndromes, since the deletion on the short arm of chromosome 5 is often of a size that is already visible in conventional chromosomal analysis. Smaller deletions can be detected by molecular cytogenetics or by chromosomal microarrays (CMA). Deletion 5p is one of the most common autosomal deletions with a frequency of about 1:15,000 to 1:50,000. About 80% are de novo deletions and about 10 to 15% result from a parental balanced structural aberration.
The syndrome name is derived from the striking high-pitched cry of affected newborns, which is pathognomonic for the syndrome. The infants usually have muscle hypotonia, microcephaly, epicanthus and downward slanting eyelid folds, clinodactyly and, occasionally, cardiac defects. Development is significantly delayed, especially with regards to speech, and the IQ of adolescents and adults is in the range of the most severe intellectual disability (< 20). Life expectancy is not significantly reduced unless complex cardiac defects are present. With smaller or interstitial deletions, patients often have only partial symptoms, such as the prominent cry as newborns but with no signs of dysmorphia or a less pronounced developmental disorder.
Elmakky et al. 2014, Eur J Med Genet 57:145 / Mainardi 2006, Orphanet J Rare Dis I:33 / Zhang et al. 2005, Am J Hum Genet 76:312