Mosaic tetrasomy 21 in severe mental handicap.
D002675:Child, Preschool; D002869:Chromosome Aberrations / Q000175:diagnosis*; D025063:Chromosome Disorders; D002904:Chromosomes, Human, 21-22 and Y; D005347:Fibroblasts; D006801:Humans; D008607:Intellectual Disability / Q000235:genetics; D008214:Lymphocytes; D008297:Male; D009030:Mosaicism