5p syndrome, also known as cri-du-chat syndrome, is a rare genetic disorder caused by the loss (deletion) of a piece on the short arm of chromosome 5. The name ("cat crying syndrome") comes from the typical high-pitched cry of affected babies, which is reminiscent of a cat meowing.

Children with 5p syndrome usually show developmental delay, mental retardation, low muscle tone (hypotonia) and characteristic facial features such as a round face, wide-set eyes and low-set ears. Feeding and speech difficulties and motor problems are also common.