CHROMOSOME ANALYSIS OF PARALLEL SHORT-TERM CULTURES FROM 4 TESTICULARGERM-CELL TUMORS

Cytogenetic analysis has been carried out on 17 parallel short-term cu ltures from four malignant testicular teratomas of intermediate differ entiation (MTI), two of them combined with seminomas. Clonal developme nt was seen in three tumors, with most of the variation involving diff erent rearrangements of chromosome 1. Two copies of the i(12p), charac teristic of testicular germ-cell tumors, were present in the two tumor s with yolk sac elements, a single i(12p) and a 12q - were found in an MTI that had metastasized, and a rearrangement of chromosome 12 conta ining centromeric chromatin from chromosome 18 was found instead of th e i(12p) in a mixed tumor. A 13p + marker containing Q-negative materi al was seen in two of the tumors, with a der(7)t(Y;7) in one. Chromoso mes 1, 3, 6, 7, 8, 12, 17, and X were invariably overrepresented eithe r as complete or partial trisomies, and chromosomes 4, 5, 13, and 18 w ere underrepresented in all four tumors, strengthening the idea that t umor suppressor genes on the latter four chromosomes, all of which sho w some loss of heterozygosity with DNA markers, may be important in tu mor progression.