MDM4 and neoplasm: Isolated amplification of DNA sequences at chromosomal regions other than 7p11.2 was found in 10/80 cases (13%); this included isolated amplification of 4q12 (where the PDGFRA gene is coded) in 4/80 cases (5%), 12q14.1 (where the CDK4 gene is coded) in 3/80 cases (4%), 1q32.1 (this chromosomal region contains the MDM4 gene) in another 2/80 tumors (3%) and 16q in one tumor (1%) without any annotated gene being coded in the amplified DNA sequences from this later chromosomal region (Table 1).