Human testicular cancer. Changes in autosomal dosage

Fourteen males with testicular tumor were studied by Southern blot hybridization. Probes detecting restriction fragment length polymorphisms at loci on 14 autosomes were used. In comparison with DNA from normal tissue, clear differences in allele dosage were observed in tumor DNA at loci mapping to the short and/or long arm of chromosomes 5, 7, and 12 in six patients with testicular germ cell tumor. In three patients, all three chromosomes were affected. Tumor DNA of the same patients also showed an imbalance between the sex chromosomes, with a relative deficiency of DNA of Y-chromosomal and a concurrent excess of DNA of X-chromosomal origin. Restriction fragment length polymorphisms from chromosomes 1, 3, 9, 11, 13, 16, 17, 18, 19, 21, and 22 did not show any consistent changes in tumor DNA. Possible consequences of the above alterations as a result of gene dosage effects, oncogene activation, and unmasking of tumor suppressor genes are discussed.