Complexity of 12q13-22 amplicon in liposarcoma: microsatellite repeat analysis.

The 12q13-22 amplicon from four liposacroma specimens evaluated by comparative genomic hybridization was studied analyzing 55 microsatellite markers by PCR. All four specimens were informative in at least 34 loci; an amplification or allelic imbalance was identified with four to 17 markers. The amplicons were discontinuous; there were non-amplified marker loci between the amplified marker loci. These findings indicate the presence of separate amplicons in the 12q13-22 region. Evidence of the concomitant gain of one allele and loss of the other allele was found with several markers in one tumor and with one marker in two tumor specimens. Southern blotting showed amplification of CDK4 and MDM2 in all four specimens.