MDM2 AMPLIFICATION IN A PRIMARY ALVEOLAR RHABDOMYOSARCOMA DISPLAYING A T(2-13)(Q35-Q14)

This report describes a case of rhabdomyosarcoma associated with a 2;1 3 translocation and multiple double minute chromosomes. The origin of the amplified DNA was identified using comparative genomic hybridizati on, which pinpointed a unique spot at 12q13 --> q14. Band 12q13 has be en shown to contain several genes that are occasionally amplified in o ther sarcomas. Fluorescence in situ hybridization to tumor metaphases with probes specific for this region indicated that the double minutes contained the MDM2 gene but not the CDK4 gene. MDM2 amplification was further quantified by Southern hybridization, which showed a mean val ue of 25 copies per haploid genome. This is the first example of MDM2 amplification in a rhabdomyosarcoma.