Abstract: The Relationship between Abnormal Methylation of IGF-2 Exon 9 andWilms TumorHuan CHENG, Jiantang SUCorrespondence to: Jiantang SU, E-mail: kuaisulaogong001@163.comDepartment of Urology, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, ChinaAbstract Objective: To explore the relationship between the methylated status of IGF-2 exon 9 and the expression of IGF-2gene and to investigate the mechanism of IGF-2 exon 9 CpG island methylation in Wilms tumor. Methods: The IGF-2 exon 9 methyla-tion status and IGF2 gene expression in 42 tissue samples of Wilms tumor and corresponding normal tissue were detected by methyla-tion-sensitive restriction enzyme PCR ( MSP ) and allele-specific IGF2 gene expression analysis. Results: The rate of IGF-2 exon 9methylation was 16.6% in Wilms tumor tissue samples and 95.23% in normal tissue, with a significant difference ( P < 0.01 ). The rateof IGF-2 exon 9 methylation was significantly different among different pathological types ( P < 0.01 ). Biallelic expression of theIGF-2 in exon 9 unmethylated tissue was significantly higher than in tissue with exon 9 methylation ( P < 0.05 ). Conclusion: IGF-2exon 9 unmethylation may be the cause of biallelic expression of the IGF and may involve Wilms tumorigenesis. IGF-2 exon 9 plays animportant role in regulating the proliferation and differentiation of nephroblastoma. The molecular mechanisms of Wilms tumor offer atheoretical basis for early diagnosis and treatment.Keywords Wilms tumor; Insulin-like growth factors; DNA methylation