Ramprasad Vedam L, Madhavan Jagadeesan, Murugan Sakthivel, Sujatha Jagadeesh, Suresh Seshadri, Sharma Tarun, Kumaramanickavel Govindasamy
SN ONGC Department of Genetics and Molecular Biology, Vision Research Foundation, Sankara Nethralaya, Chennai, India.
Mol Diagn Ther. 2007;11(1):63-70. doi: 10.1007/BF03256223.
This study was conducted with two objectives. The first was to estimate the frequency of loss of heterozygosity (LOH) of the RB1 gene as a mechanism in disease causation in tumors of patients from India. The second objective was to employ RB1 molecular deletion and microsatellite-based linkage analysis as laboratory tools, while counseling families with a history of retinoblastoma (RB).
DNA was extracted from peripheral blood and tumors of 54 RB patients and their relatives. Eight fluorescent microsatellite markers, both intragenic and flanking the RB1 gene, were used. After PCR amplification, samples were run on an ABI PRISM 310 genetic analyzer for LOH, deletion detection, and haplotype generation.
LOH was found in conjunction with tumor formation in 72.9% of RB patients (39/54 patients; p=0.001; 95% CI 0.6028, 0.8417); however, we could not associate various other clinical parameters of RB patients with the presence or absence of RB1 LOH. Seven germline deletions (13% of RB patients) were identified, and the maternal allele was more frequently lost (p=0.01). A disease co-segregating haplotype was detected in two hereditary autosomal dominant cases.
LOH of the RB1 gene could play an important role in tumor formation. Large deletions involving RB1 were observed, and a disease co-segregating haplotype was used for indirect genetic testing. This is the first report from India where molecular testing has been applied for RB families in conjunction with genetic counseling. In tertiary ophthalmic practice in India, there is an emerging trend towards the application of genetical knowledge in clinical practice.
本研究有两个目的。第一个目的是评估RB1基因杂合性缺失（LOH）作为印度患者肿瘤疾病病因机制的频率。第二个目的是在为有视网膜母细胞瘤（RB）病史的家庭提供咨询时，将RB1分子缺失和基于微卫星的连锁分析用作实验室工具。
从54例RB患者及其亲属的外周血和肿瘤中提取DNA。使用了8个荧光微卫星标记，包括RB1基因内部和侧翼的标记。PCR扩增后，将样本在ABI PRISM 310基因分析仪上进行LOH、缺失检测和单倍型生成分析。
72.9%的RB患者（39/54例患者；p=0.001；95%CI 0.6028，0.8417）中发现LOH与肿瘤形成相关；然而，我们无法将RB患者的各种其他临床参数与RB1 LOH的存在与否联系起来。鉴定出7例种系缺失（占RB患者的13%），且母本等位基因更常丢失（p=0.01）。在2例遗传性常染色体显性病例中检测到与疾病共分离的单倍型。
RB1基因的LOH可能在肿瘤形成中起重要作用。观察到涉及RB1的大片段缺失，并使用与疾病共分离的单倍型进行间接基因检测。这是印度的首份报告，其中分子检测已与遗传咨询一起应用于RB家庭。在印度的三级眼科实践中，在临床实践中应用遗传学知识的趋势正在兴起。
