MDM2 and neoplasm: It is reasonable to assume that in the present tumor both MDM2 amplification and the fusion genes PTGES3-PTPRB, HMGA2-DYRK2, TMBIM4-MSRB3 and USP15-CNTN1 are located on the ring chromosome (Fig. 2) although lack of suitable material prevented us from determining this with certainty.