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Cri du chat syndrome, also called deletion 5p syndrome, or 5p minus, is a rare genetic disorder due to a missing portion of chromosome 5. It was first described by Lejeune in 1963. The 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.
Signs and symptoms
Its name, meaning cry of the cat, is from the distinctive mewing sound made by infants with the disorder. As babies, patients tend to be squirmy with a mewing cry, ascribed to abnormal laryngeal development. The cry becomes less distinctive with age. Individuals with cri du chat syndrome are often underweight at birth. 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. Characteristic facial features include a round face, epicanthal folds, low set ears, strabismus, facial asymmetry and downward slanting palpebral fissures.
Genetics
Cri du chat syndrome is due to a partial deletion of the short arm of chromosome number 5. Approximately 85% of cases results from a sporadic de novo deletion, while about 15% are due to unequal segregation of a parental chromosome translocation. Although the size of the deletion varies, a deletion at region at 5p15.3 is responsible for the unique cry and the critical region of 5p15.2 is responsible for the other features. The deletion is of paternal origin in about 80% of cases in which the syndrome is de novo. Genetic counseling and genetic testing may be offered to families with Cri du chat syndrome.
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