Quantification of additional short arms of chromosome 12 in germ cell tumours using the polymerase chain reaction

Male germ cell tumours are characterised by the over-representation of 12p sequences, most often in the form of isochromosome i(12p). This study describes the development of a quantitative detection system for additional copies of 12p employing the polymerase chain reaction (PCR). The validity of this method was assessed on two i(12p) containing tumour cell lines in which the number of i(12p) was determined by fluorescence in situ hybridisation. Fourteen primary male germ cell tumours were analysed using the PCR-based method. While 3/8 seminomatous germ cell cancers did not contain any additional 12p, all 6 non-seminomatous tumours did and the severity of the disease correlated with the respective copy number. The ease of the PCR-based method makes it possible for the quantification of additional 12p to become a routine diagnostic and prognostic tool for testicular germ cell tumours, thereby helping to define the role of the i(12p) anomality in larger retrospective studies.