Similar MLLT1 insertion/deletion variants were not identified in other TARGET tumours (neuroblastoma, osteosarcoma, acute lymphocytic and myelogenous leukaemia, unpublished), nor have they been reported in dbSNP 134 or 135 (ref. 7), COSMIC v69 (ref. 8), or in the 1000 Genomes Pilot Projects 1, 2, and 3 (ref. 9). This evidence concerns the gene MLLT1 and osteosarcoma.