Gains in chromosomes 7, 8q, 15q and 17q are characteristic changes in malignant but not in benign peripheral nerve sheath tumors from patients with Recklinghausen's disease.

In order to investigate typical genomic alterations in patients with Recklinghausen's disease (NF1) we studied one from each of the six patients with NF1 several benign and/or malignant tumors. By means of comparative genomic hybridization (CGH) gained results from six benign neurofibromas and 14 malignant peripheral nerve sheath tumors (MPNSTs) were compared with four benign peripheral nerve sheath tumors (BPNSTs) from patients without NF1. In all 14 MPNSTs DNA sequence copy number changes were detected with a mean value of 13.5 imbalances per sample. The most frequent gains were in 8q, 17q (12 tumors each), 7p, 15q (ten tumors each), and 7q (nine tumors). We found ten high-level amplifications in nine of the 14 samples. In two cases, the high-level amplification involved 7p14-pter and 17q24-qter as well. The most frequent loss was in 17p (seven tumors). The benign neurofibromas from NF1-patients and the sporadic BPNSTs revealed only partially DNA sequence copy number changes without any distinct pattern. The gains of #7, 8q, 15q, and 17q were found exclusively in MPNSTs but not in neurofibromas and are supposed to be associated with malignant tumor progression. In comparison of the results of the 14 MPNSTs from NF1-patients with the results of previously published 20 sporadic MPNSTs, we found that the gain of 8q occurs most frequently in both tumor groups. Of course additionally in the sporadic MPNSTs there were more frequent gains of 5p, #6, and statistically significant gains of 20q. On the other hand in the MPNSTs from NF1-patients the most frequent gains were found in #7, and statistically significant in 15q, and 17q.