Prediction of retinoblastoma and osteosarcoma: linkage analysis of families by using polymorphic markers around RB1 locus.

PURPOSE Linkage analysis at the retinoblastoma gene (RB1) locus is required for identification of individuals at risk of developing retinoblastoma and osteosarcoma. Identification of disease causing mutations is necessary for accurate risk prediction. However, the usefulness of direct mutation analysis is impeded by the size and complexity of the RB1 gene. The authors report an alternative polymerase chain reaction (PCR)-based method for genotyping the RB1 locus using polymorphic microsatellite markers for the prediction of risk of developing the disease. MATERIALS AND METHODS For this purpose, we have used 2 intragenic microsatellite markers of the RB1 gene, D13S153 and RB1.20 VNTR, and 2 flanking markers D13S218 and D13S176. The segregations of the 4 polymorphic markers within and flanking the RB1 gene were analyzed in 3 families with osteosarcoma and 2 families with retinoblastoma. RESULTS AND CONCLUSION Our results showed that linkage analysis of families by using the intragenic and flanking markers could be applied to detect carriers and for prenatal diagnosis in families with retinoblastoma and osteosarcoma. Moreover, this PCR-based genotyping is simpler and faster than other conventional methodologies.