McIntyre J F, Smith-Sorensen B, Friend S H, Kassell J, Borresen A L, Yan Y X, Russo C, Sato J, Barbier N, Miser J
Division of Molecular Genetics, Massachusetts General Hospital, Boston 02129.
J Clin Oncol. 1994 May;12(5):925-30. doi: 10.1200/JCO.1994.12.5.925.
We investigated the possibility that a significant proportion of children with osteosarcoma harbor germline mutations of the p53 tumor suppressor gene and, therefore, this subgroup of pediatric cancer patients should be considered for large-scale predictive testing.
Genomic DNA extracted from peripheral-blood leukocytes from 235 unselected children with osteosarcoma from 33 institutions were screened for the presence of germline p53 mutations using constant denaturant gel electrophoresis (CDGE). Exons 5 through 8 were evaluated in all patients and exon 2 and exon 9 were analyzed in 59 and 95 patients, respectively. Those samples that showed aberrant migration on CDGE were sequenced or analyzed by restriction enzyme digestion of polymerase chain reaction (PCR) products to confirm the nature of the gene alteration.
In 18 samples, CDGE showed fragments of the p53 gene with altered electrophoretic mobilities compared with wild-type p53. DNA sequencing showed that 11 samples had an identical, previously described polymorphism. The other seven contained heterozygous p53 mutations located in exon 5 (n = 3), exon 6 (n = 1), exon 7 (n = 1), and exon 8 (n = 2). Six alterations were missense mutations and one was a nonsense mutation. Three of these patients had first-degree relatives with cancer. One of these three kindreds had a family history consistent with Li-Fraumeni syndrome (LFS).
We identified germline p53 mutations in seven of 235 (3.0%) children with osteosarcoma. Four of these mutations were found in patients who did not have first-degree relatives with cancer. Although genetic transmission of the altered p53 gene could not be tested in this survey because of how it was designed, it is possible that predictive testing for p53 mutations could identify unaffected relatives of gene carriers who also have a high risk for the development of cancer. This study provides evidence for the importance of considering children with osteosarcoma for predictive testing for germline p53 mutations.
我们调查了相当一部分骨肉瘤患儿携带p53肿瘤抑制基因种系突变的可能性，因此，应考虑对这一亚组儿童癌症患者进行大规模预测性检测。
使用恒定变性剂凝胶电泳（CDGE），对来自33个机构的235例未经选择的骨肉瘤患儿外周血白细胞中提取的基因组DNA进行种系p53突变检测。所有患者均评估了第5至8外显子，分别对59例和95例患者分析了第2外显子和第9外显子。那些在CDGE上显示异常迁移的样本通过对聚合酶链反应（PCR）产物进行测序或限制性酶切分析，以确认基因改变的性质。
在18个样本中，与野生型p53相比，CDGE显示p53基因片段的电泳迁移率发生改变。DNA测序表明，11个样本具有相同的、先前描述的多态性。另外7个样本含有位于第5外显子（n = 3）、第6外显子（n = 1）、第7外显子（n = 1）和第8外显子（n = 2）的杂合p53突变。6个改变为错义突变，1个为无义突变。这3名患者中有3名有患癌的一级亲属。这三个家族中有一个家族史符合李-弗劳梅尼综合征（LFS）。
我们在235例骨肉瘤患儿中发现了7例（3.0%）种系p53突变。其中4例突变见于没有患癌一级亲属的患者。尽管由于本研究的设计方式，无法在本次调查中检测p53基因改变的遗传传递情况，但对p53突变进行预测性检测有可能识别基因携带者的未受影响亲属，这些亲属患癌风险也很高。本研究为考虑对骨肉瘤患儿进行种系p53突变预测性检测的重要性提供了证据。
