Abstract
Retinoblastoma, a childhood malignancy derived from the retinal cell, develops by the two-hit inactivation of the RB1 gene on chromosomal region 13q14 with the incidence of 1 out of 15,000 birth. Tumors occur bilaterally in about 30% of the retinoblastoma patients, while the unilateral tumors develop in the other 70% of the patients. About 30–40% of the patients, including all cases of the familial and/or bilateral retinoblastoma and about 10% of the unilateral retinoblastoma patients, harbor the germline mutation of the RB1 gene and categorized into the hereditary retinoblastoma, in which phenotype of the tumor susceptibility segregates as an autosomal dominant trait with the prevalence of about 90%. When the tumors are treated in the early stage, the prognosis of the retinoblastoma is fairly good and satisfactory. However, the secondary tumors, including osteosarcomas and soft-tissue sarcomas, develop frequently in the teenage survivors of the retinoblastoma, especially in the patients who were received a radiation therapy, providing additional problems for the control of the hereditary retinoblastoma patients. Recently, DNA diagnosis of the retinoblastoma by the structural analysis of the RB1 gene has been established to identify the hereditary retinoblastoma patients or the carriers of the RB1 mutation. Using the peripheral blood lymphocytes, nucleotide substitutions or small insertions/deletions of the gene can be identified by the PCR-based DNA sequencing of the RB1 gene, whereas the gross chromosomal alterations as well as gene deletions can be detected by the fluorescence in situ hybridization. These analyses could identify the germline mutation of the RB1 gene in about 70–80% of the hereditary retinoblastoma patients, providing useful information for the treatment and control of the retinoblastoma.
