Molecular detection of metastatic retinoblastoma cells by reverse transcription polymerase reaction for interphotoreceptor retinoid-binding protein mRNA: A case report

BACKGROUND. In the current study, the authors report a 4 year old girl with disseminated retinoblastoma. To find sensitive and specific molecular markers for detection of retinoblastoma cells in blood and marrow, the authors evaluated three photoreceptor-associated gene transcripts by using reverse transcription polymerase chain reaction (RT-PCR). METHOD. Samples of bone marrow and blood were obtained from healthy donors and the patient. RT-PCR was performed to detect the cone α′-subunit of cGMP phosphodiesterase (cone α′-PDE), the rod β-subunit of cGMP (rod β-PDE), and the interphotoreceptor retinoid-binding protein (IRBP) gene transcript in RNA extracted from the samples. RESULTS. While no expression of rod β-PDE or IRBP was detected in any of the normal samples, expression of cone α′-PDE was detected in two out of seven normal marrow samples. Expression of rod β-PDE was not detected in the patient samples. Expression of IRBP was detected in the patient samples obtained from iliac bone marrow before intensive chemotherapy but not thereafter. CONCLUSION. RT-PCR for IRBP was a useful method for detecting metastatic retinoblastoma cells as well as for evaluating the therapeutic effects of treatment in this particular case.