MspI digestion of PCR-amplified DNA from patients with giant cell tumor of bone as compared to positive and negative control DNA. Lane 1, heterozygous positive control showing both the 316-bp (mutant allele) and 235-bp (normal allele) fragments; lanes 2–10, GCT patients showing normal 235-bp fragments after digestion; lane 11, normal control; lane 12, normal control DNA but uncut with MspI showing the 316-bp fragments. Lanes 2 and 4 represent DNA from GCT patients without telomeric associations observed in short-term cultured cells. Lanes 3, 5, and 6–10 represent DNA from GCT patients with telomeric associations observed in short-term cultured cells, with lanes 3, 5, and 6 having 11p terminus involved in telomeric associations in at least one of 30 cells while the remaining GCT patients with telomeric associations did not have 11p involvement.