In November, 1963, Lejeune et al1 reported on three cases of infants who exhibited certain congenital abnormalities in common, including a strange, high-pitched, plaintive cry which Lejeune considered to be reminiscent of the cry of a cat. Chromosome analyses of these patients had revealed that in all cases one of the chromosomes of the 4-5 group was lacking a portion of the short arm. Lejeune feels that the deleted chromosome is number 5.
After this first report, Lejeune and his group studied two additional children with the same syndrome. From Prof. J. A. Böök, he also received information about a sixth case which was later referred to separately (Böök et al2). The original three cases and the additional three were presented in a second paper on the subject by Lejeune et al3 in April, 1964. The presence of the characteristic cry in all of the cases studied
MACINTYRE MN, STAPLES WI, LaPOLLA J, HEMPEL JM. The "Cat Cry" Syndrome. Am J Dis Child. 1964;108(5):538-542. doi:10.1001/archpedi.1964.02090010540014