Constitutional karyotypes in retinoblastoma.

The improvement of chromosome banding techniques has much increased the frequency of detected forms of retinoblastoma. Ten rearrangements involving 13q14 were observed in a series of 105 retinoblastoma patients including: five de novo deletions, one of them with suspected mosaicism; one de novo apparently balanced translocation; four deletions due to three familial insertions. Such a mechanism could account for pedigrees showing transmission of the tumor through unaffected carriers. Apparently unrelated rearrangements were also observed. Clinical aspects of these constitutional rearrangements are briefly discussed. Comparison with the literature data is presented.