Mosaicism for trisomy 3q arising from an unbalanced, de novo t(3;15)

We report on a 2% year old girl who is dysmorphic, developmentally delayed, and mosaic for an unbalanced, de novo translocation between chromosomes 3 and 15. The karyotype from peripheral blood lymphocytes is 46,XX (50) and the karyotype from skin fibroblasts is 46,XX (28)/46,XX,der(15)t(3; 15) (q11;p11) (23). The mechanism for the generation of this unbalanced, de novo translocation is discussed.