Chromosomal imbalances revealed in primary rhabdomyo-sarcomas by comparative genomic hybridization.

Background: Previous cytogenetic studies revealed aberrations varied among the three subtypes of rhabdomyosarcoma. We profiled chromosomal imbalances in the different subtypes and investigated the relationships between clinical parameters and genomic aberrations.

Methods: Comparative genomic hybridization was used to investigate genomic imbalances in 25 cases of primary rhabdomyosarcomas and two rhabdomyosarcoma cell lines. Specimens were reviewed to determine histological type, pathological grading and clinical staging.

Results: Changes involving one or more regions of the genome were seen in all rhabdomyosarcomal patients. For rhabdomyosarcoma, DNA sequence gains were most frequently (> 30%) seen in chromosomes 2p, 12q, 6p, 9q, 10q, 1p, 2q, 6q, 8q, 15q and 18q; losses from 3p, 11p and 6p. In aggressive alveolar rhabdomyosarcoma, frequent gains were seen on chromosomes 12q, 2p, 6p, 2q, 4q, 10q and 15q; losses from 3p, 6p, 1q and 5q. For embryonic rhabdomyosarcoma, frequent gains were on 7p, 9q, 2p, 18q, 1p and 8q; losses only from 11p. Frequently gained chromosome arms of translocation associated with rhabdomyosarcoma were 12q, 2, 6, 10q, 4q and 15q; losses from 3p, 6p and 5q. The frequently gained chromosome arms of nontranslocation associated with rhabdomyosarcoma were 2p, 9q and 18q, while 11p and 14q were the frequently lost chromosome arms. Gains on chromosome 12q were significantly correlated with translocation type. Gains on chromosome 9q were significantly correlated with clinical staging.

Conclusions: Gains on chromosomes 2p, 12q, 6p, 9q, 10q, 1p, 2q, 6q, 8q, 15q and 18q and losses on chromosomes 3p, 11p and 6p may be related to rhabdomyosarcomal carcinogenesis. Furthermore, gains on chromosome 12q may be correlated with translocation and gains on chromosome 9q with the early stages of rhabdomyosarcoma.