[Retinoblastoma gene analysis in a patient with osteosarcoma following previous bilateral retinoblastoma].

In a native osteosarcoma specimen of a patient cured of a bilateral retinoblastoma eight years before we found a homozygous deletion of a 7.5 kb Hind III-fragment within the retinoblastoma gene and a hemizygous deletion of the same fragment in its constitutional cells. In a native osteosarcoma tissue of a lung metastasis of a patient with sporadic osteosarcoma the Rb-gene-analysis did not reveal any deletion within the gene. This might be due to the fact that the used c-DNA-probe did not detect point mutations. Nevertheless, the possibility of additional or alternative transforming events should be kept in mind.