Karyotype of a patient with cri du chat syndrome (also known as Cat cry syndrome), computer illustration. Cri du chat syndrome is a group on syndromes including mental retardation, high-pitched cry sounds (like a cat), microcephaly, low birth weight, hypertelorism, a small jaw, low-set ears, partial webbing of fingers or toes, skin tags in front of the ear, slow development of motor skills, and a simian crease in the palm of the hand. The syndrome is caused by missing information on chromosome 5.