Cri-du-chat syndrome

Cri-du-chat (cat cry) syndrome is a chromosomal condition that results when a piece of chromosome 5 is missing. Infants with the condition often have a high-pitched cry that sounds like that of a cat. The disorder is characterized by severe mental retardation and delayed development, distinctive facial features, small head size (microcephaly), low birth weight, and weak muscle tone (hypotonia) in infancy.

This condition affects an estimated 1 in 20,000 to 50,000 live births. The disorder is found in people of all ethnic backgrounds and is slightly more common in females.

Cri-du-chat syndrome is a chromosomal condition related to chromosome 5.

Cri-du-chat syndrome is caused by a deletion of the end of the short (p) arm of chromosome 5 (a chromosomal change that can also be written as 5p-). The signs and symptoms of the condition are probably related to the loss of multiple genes in this region. Researchers have not yet identified all of the genes or determined why a lack of these genes leads to the characteristic features of the disorder. They have discovered, however, that a larger deletion tends to result in more severe mental retardation and developmental delays in people with cri-du-chat syndrome.

Most cases of cri-du-chat syndrome result from a deletion that occurs as a random event during the formation of reproductive cells (eggs or sperm) or early in fetal development.

About 10 percent of people with the disorder inherit the chromosome with a deleted segment 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. Balanced translocations usually do not cause any medical problems; however, they can become unbalanced as they are passed to the next generation. A deletion in the short arm of chromosome 5 is an example of an unbalanced translocation, which is a chromosomal rearrangement with extra or missing genetic material. Unbalanced translocations can cause birth defects and other health problems such as those seen in cri-du-chat syndrome.

You may find the following resources about cri-du-chat syndrome helpful.

• MedlinePlus - Health Information (3 links)
• Educational resources - Information pages (3 links)
• Patient support - For patients and families (6 links)

You may also be interested in these resources, which are designed for healthcare professionals and researchers.

• Gene Tests - DNA tests ordered by healthcare professionals
• PubMed - Recent literature
• OMIM - Genetic disorder catalog

See How are genetic conditions and genes named? in the Handbook.

The Handbook provides basic information about genetics in clear language.

• What does it mean if a disorder seems to run in my family?
• What is a chromosome?
• Can changes in chromosomes cause disorders?
• Are chromosomal disorders inherited?

These links provide additional genetics resources that may be useful.

• Genetics and health
• Resources for Patients and Families
• Resources for Health Professionals

chromosome ; deletion ; developmental delay ; gene ; mental retardation ; muscle tone ; rearrangement ; sign ; symptom ; translocation

You may find definitions for these and many other terms in the Genetics Home Reference Glossary.