Most cases of cri du chat syndrome are not inherited.The deletion occurs most often as a random event during the formation of reproductive cells (eggs or sperm) or in early fetal development.The Human Phenotype Ontology (HPO) provides the following list of features that have been reported in people with this condition.Much of the information in the HPO comes from Orphanet, a European rare disease database.You can use the Medline Plus Medical Dictionary for definitions of the terms below. The size of the deletion varies among affected individuals but studies suggest that larger deletions tend to result in more severe intellectual disability and developmental delay than smaller deletions.The signs and symptoms of cri du chat syndrome are probably related to the loss of multiple genes on the short arm of chromosome 5.If available, the list includes a rough estimate of how common a feature is (its frequency).
They are working to determine how the loss of other genes in this region contributes to the characteristic features of cri du chat syndrome.Infants with this condition often have a high-pitched cry that sounds like that of a cat.The disorder is characterized by intellectual disability and delayed development, small head size, low birth weight, weak muscle tone in infancy, and distinctive facial features.Most affected individuals do not have a history of the disorder in their family.
About 10 percent of people with cri du chat syndrome inherit the chromosome abnormality from an unaffected parent.
In these cases, the parent carries a chromosomal rearrangement called a balanced translocation, in which no genetic material is gained or lost.