Bilateral retinoblastoma with de novo constitutional balanced translocation t(2;9)(q11;p11)

Constitutional balanced translocations in alveolar rhabdomyosarcoma

Chromosomal analysis of tumor tissue from two children with alveolar rhabdomyosarcoma revealed t(1;5)(q32;q31) and t(1;22)(q21;q11.2) in all metaphases examined, respectively. Peripheral blood lymphocytes carried the same cytogenetic abnormality as that of the tumor cells in both patients. Parental lymphocytes were karyotypically normal in the patient with t(1;22), indicating a de novo constitutional translocation, but t(1;5) was paternally inherited in the other patient. The presence of constitutional translocations in these two children might have contributed to the development of alveolar rhabdomyosarcoma.

Constitutional karyotype in retinoblastoma. Case report and review of literature

High resolution karyotype was performed in 13 retinoblastoma patients. A mosaic pattern for del(13)(q14.1;q14.3) was found in a girl with sporadic bilateral retinoblastoma and midface dysmorphism. In addition, 162 cases of 13q aberrations were reviewed, including 140 retinoblastoma patients and 22 non-penetrance 13q14 deletions. Some epidemiological and genetic involvements are discussed.

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.