Jiang Ye-ping, Shen Ying, Sun Ning, Wang Hui
Department of Pediatric Internal Medicine, Beijing Children's Hospital Affiliated to Capital Medical University, Beijing 100045, China.
Zhonghua Er Ke Za Zhi. 2009 Oct;47(10):762-6.
Wilms' tumor (WT) is the most common malignant renal tumor in childhood. The WT1 gene located at 11p13 was identified in 1990 as a tumor suppressor gene important in the development in WT. The WT1 gene consists of 10 exons, with exons 1 to 6 encoding an N-terminal proline- and glutamine-rich transactivational domain, and exons 7 to 10 encoding a C-terminal zinc-finger domain involved in DNA binding. In China we know little about the frequency and genotype of WT1 mutations in Chinese WT patients. This study aimed to determine the frequency and genotype of WT1 mutations in children with nonsyndromic WT in China.
We collected peripheral blood of WT patients treated in Beijing Children's Hospital. Genomic DNA of 54 WT patients was isolated from blood samples. All coding WT1 exons and their flanking intronic sequences were amplified by PCR method. The amplified PCR products from all individuals were then subjected to automatic DNA sequencing.
Four different constitutional WT1 mutations were identified in four children. Three mutations are predicted to produce truncated protein. One mutation is missense. Of the four mutations, three had not been reported before. Patient 1 had a 1006 A > T transition in exon 7, which caused (336)Lys to become a stop codon (K336X). DNA sequence analyses in patient 2 indicated the point mutations in exon 9 which was a 1168 C > T substitution and caused (390)Arg to become a stop codon (R390X). It indicated a point mutations in exon 6 in patient 3 which was a 814 G > T substitution and resulted in (272)Glu to become a stop codon (E272X). In patient 4 there was a homozygous mutation in exon 10. The mutation was a 1228 A > G substitution and resulted in (410)Ser to become a Gly codon (S410G).
Constitutional WT1 mutations occur at a low frequency (7.4%) in Chinese patients with Wilms' Tumor. It is similar to the results of overseas study. Four WT1 gene mutations were confirmed, three were nonsense, one was missense.
肾母细胞瘤（WT）是儿童期最常见的恶性肾肿瘤。位于11p13的WT1基因于1990年被鉴定为在WT发生发展中起重要作用的肿瘤抑制基因。WT1基因由10个外显子组成，外显子1至6编码富含脯氨酸和谷氨酰胺的N端反式激活结构域，外显子7至10编码参与DNA结合的C端锌指结构域。在中国，我们对中国WT患者中WT1突变的频率和基因型了解甚少。本研究旨在确定中国非综合征性WT儿童中WT1突变的频率和基因型。
我们收集了在北京儿童医院接受治疗的WT患者的外周血。从血样中分离出54例WT患者的基因组DNA。通过PCR方法扩增所有编码WT1的外显子及其侧翼内含子序列。然后对所有个体的扩增PCR产物进行自动DNA测序。
在4名儿童中鉴定出4种不同的WT1基因组成性突变。3种突变预计会产生截短蛋白。1种突变为错义突变。在这4种突变中，有3种以前未被报道过。患者1在外显子7中有1006 A>T转换突变，导致（336）赖氨酸变为终止密码子（K336X）。患者2的DNA序列分析表明外显子9中有点突变，即1168 C>T替换，导致（390）精氨酸变为终止密码子（R390X）。患者3在外显子6中有一个点突变，即814 G>T替换，导致（272）谷氨酸变为终止密码子（E272X）。患者4在外显子10中有一个纯合突变。该突变是1228 A>G替换，导致（410）丝氨酸变为甘氨酸密码子（S410G）。
中国肾母细胞瘤患者中WT1基因组成性突变的发生率较低（7.4%）。这与国外研究结果相似。确认了4种WT1基因突变，3种为无义突变，1种为错义突变。
