Greger V, Debus N, Lohmann D, Höpping W, Passarge E, Horsthemke B
Institut für Humangenetik, Universitätsklinikum Essen, Germany.
Hum Genet. 1994 Nov;94(5):491-6. doi: 10.1007/BF00211013.
The retinoblastoma susceptibility (RB1) gene contains an unmethylated CpG-rich island at its 5' end. Using methylation-sensitive restriction enzymes, we have investigated the methylation status of this island in 21 sporadic unilateral retinoblastomas and 30 hereditary retinoblastomas. Three sporadic unilateral tumors were found to have hypermethylated RB1 alleles. In two tumors, the paternal allele was methylated, whereas the maternal allele had been lost. Cultured cells from one of these tumors were studied by the reverse transcription polymerase chain reaction and found to have a reduced level of RB1 mRNA. The third tumor had retained constitutional heterozygosity, and the paternal allele was specifically methylated. The combined data from previously published reports and from this study show that hypermethylation of the RB1 gene occurs in 13% of sporadic unilateral tumors and may reduce gene activity.
视网膜母细胞瘤易感基因（RB1）在其5'端包含一个未甲基化的富含CpG的岛。我们使用甲基化敏感的限制性内切酶，研究了21例散发性单侧视网膜母细胞瘤和30例遗传性视网膜母细胞瘤中该岛的甲基化状态。发现3例散发性单侧肿瘤的RB1等位基因发生了高甲基化。在2例肿瘤中，父本等位基因发生甲基化，而母本等位基因丢失。对其中1例肿瘤的培养细胞进行逆转录聚合酶链反应研究，发现其RB1 mRNA水平降低。第3例肿瘤保留了体质性杂合性，且父本等位基因发生了特异性甲基化。先前发表的报告和本研究的综合数据表明，RB1基因的高甲基化发生在13%的散发性单侧肿瘤中，可能会降低基因活性。
