TELOMERIC ASSOCIATIONS IN THE PROGRESSION OF CHROMOSOME-ABERRATIONS IN PEDIATRIC SOLID TUMORS

Telomeric association (tas) is a cytogenetic phenomenon iri which chro mosome ends fuse to form dicentric, multicentric, and ring chromosomes . We observed clonal tas in six pediatric solid tumors of various type s and histological grades studied using short-term in situ culture and G-banding techniques. These tumors included a neurilemoma, an undiffe rentiated (embryonal) sarcoma of the liver (UESL), two anaplastic astr ocytomas (AA), one case of glioblastoma multiforme (GBM), and a neurob lastoma (NB) of the kidney. Cytogenetic data from all six tumors demon strated multiple numerical and structural aberrations including tas. T he tas appeared to be a secondary aberration in these tumors, however, it was possible to follow the progression of the telomeric chromosome aberrations in several cases. In all but one cdse (UESL) the loss of chromosome segments occurred. Tas of 11p was observed in three of the six tumors, two of which showed the subsequent loss of 11p (AA and AB) , In addition, tas of 4p was seen in three tumors, two of which showed clonal fas of 4p with 22q. Tas of 10p, 21p, and 22q were all observed in at least two different tumors. The clonal telomeric fusions of 4p with 22q, recurring tas of 11p, and the subsequent loss of the short a rm of II demonstrated here, suggests that some chromosome regions are subject to nonrandom instability and sometimes loss.