Case studies of three "XXYY" children.
D002648:Child; D002675:Child, Preschool; D006801:Humans; D007804:Language Development; D008297:Male; D011578:Psycholinguistics; D012729:Sex Chromosome Aberrations / Q000150:complications*; D013064:Speech Disorders / Q000209:etiology* / Q000628:therapy; D013070:Speech Therapy