COMPARATIVE GENOMIC HYBRIDIZATION OF GERM-CELL TUMORS OF THE ADULT TESTIS - CONFIRMATION OF KARYOTYPIC FINDINGS AND IDENTIFICATION OF A 12P-AMPLICON

Comparative genomic hybridization (CGH) was carried out on 15 primary testicular germ cell tumors (TGCT) of adolescents and adults and two m etastatic residual tumors after chemotherapeutic treatment. The result s were compared with karyotypic data obtained form the same tumor spec imens after direct harvesting of metaphases or short-term in vitro cul ture. Both techniques revealed that the most consistent abnormality in primary TGCT is gain of 12p-sequences. Although in most cases overrep resentation of the complete short arm was observed, CGH revealed a spe cific amplification of 12p11.1-p12.1 region in two independent primary tumors. In addition, loss of (parts of) chromosome 13 (always involvi ng q31-qter), and gain of (parts of) chromosome 7 (mostly involving q1 1), (parts of) chromosome 8, and the X chromosome were detected in mor e than 25% of the rumors by this latter technique. Loss of 6q15-q21 in both residual tumors analyzed may suggest a role for this anomaly in acquired resistance to chemotherapeutic treatment. Overall, the CGH an alyses confirmed gains and losses of certain chromosomal regions in TG CT as observed by karyotyping, and thus support their role in the deve lopment of these neoplasms. The amplification of a restricted region o f 12p in primary TGCT confirms and extends our previous observations a nd, as such, represents an important step forward in the identificatio n of gene(s) on 12p relevant far the pathogenesis of these tumors.