Chromosome features of two retinoblastomas.

Giemsa-banded chromosomal analysis of two unilateral retinoblastoma tumors from unrelated patients with normal constitutional chromosomes revealed near-diploid karyotypes with multiple structural rearrangements. The two tumors shared aberrations of trisomy 1q, monosomy 16 and 17, and 21p+. Other aberrations were unique to each tumor. One tumor expressed a del(13) and trisomy 6p.