Cri du chat is a rare syndrome (1 in 50,000 live births) caused by a deletion on the short arm of chromosome 5. The name of this syndrome is French for "cry of the cat," referring to the distinctive cry of children with this disorder. The cry is caused by abnormal larynx development, which becomes normal within a few weeks of birth. Infants with cri du chat have low birth weight and may have respiratory problems. Some people with this disorder have a shortened lifespan, but most have a normal life expectancy.

Where does the abnormal chromosome 5 come from? In 80 percent of the cases, the chromosome carrying the deletion comes from the father's sperm.