Mutational Analysis Of The WT1Gene In Children With Steroid-resistant Nephrotic Syndrome In Southern Chinese Han Ethnic Group

Part One: Mutation of the WT1Gene in Female MonozygoticTwins with Steroid-resistant Nephrotic SyndromeObjective To examine mutations in the WT1gene in a family with steroid-resistantnephrotic syndrome in Chinese Han ethnic group. Methods Peripheral blood sampleswere collected for genetic analysis from female monozygotic twins and their parents,as well as older sister. We studied as controls50unrelated adult volunteers in ChineseHan ethnic group whose urinalyses were normal. Genomic DNA was isolated fromperipheral blood leucocytes. All exons and exon-intron boundaries of the WT1genewere amplified by polymerase chain reaction. Mutational analysis was performed bydirect sequencing. Results The twins presented with incomplete Denys-Drashsyndrome and isolated steroid-resistant nephrotic syndrome, respectively. Aheterozygous variant1180C>T in the WT1gene, resulting in anarginine-to-tryptophan (R394W) substitution, was identified in both twins, whereas itwas not found in their parents or older sister or the50controls. Moreover, three WT1polymorphisms,126C>T,903A>G, and IVS7–32C>A, were also found in the twins.Conclusion An identical mutation in the WT1gene, R394W, was identified in bothtwins who showed different clinical phenotypes. Part Two: Mutational Analysis of the WT1Gene in Female Childrenwith Sporadic Isolated Steroid-resistant Nephrotic Syndrome inChinese Han Ethnic GroupObjective To examine mutations in the WT1gene in female children with sporadicisolated steroid-resistant nephrotic syndrome (ISRNS) in Chinese Han ethnic group.Methods Peripheral blood samples were collected for genetic analysis from14Chinese female children with sporadic ISRNS. We studied as controls38Chinesemale children with sporadic ISRNS and50unrelated adult volunteers in Chinese Hanethnic group whose urinalyses were normal. Genomic DNA was isolated fromperipheral blood leucocytes. Exons8-9and exon-intron boundaries of the WT1genewere amplified by polymerase chain reaction. Mutational analysis was performed bydirect sequencing. Results We detected a heterozygous mutation (IVS9+5G>A) of theWT1gene in one of14Chinese female children with sporadic ISRNS. The detectionrate of WT1mutations in Chinese female children with sporadic ISRNS was7.1%(1/14). Conclusion Our investigation supports the necessity of genetic examinationfor mutations in the WT1gene in Chinese female children with sporadic ISRNS. Part Three: Mutational Analysis of the WT1Gene in a Chinese MaleChild with Isolated Nephrotic Syndrome and Renal FailureObjective To examine mutations in the WT1gene in a Chinese male child withisolated nephrotic syndrome and renal failure. Methods Peripheral blood sample wascollected for genetic analysis from a Chinese male child with isolated nephroticsyndrome and renal failure，his age of onset was6.3years old. We studied as controls110unrelated adult volunteers in Chinese Han ethnic group whose urinalyses werenormal. Genomic DNA was isolated from peripheral blood leucocytes. All exons andexon-intron boundaries of the WT1gene were amplified by polymerase chain reaction.Mutational analysis was performed by direct sequencing. Results A novel variant1051A>G in exon8of the WT1gene was identified in heterozygous state, resulting inthe amino acid lysine was substituted by glutamic acid at codon351(K351E) at thelevel of the second zinc-finger domain of the WT1gene. K351E was not detected in110controls. Conclusion Our investigation supports the necessity of searching formutations in WT1in46, XY phenotypic male patients with isolated nephroticsyndrome and renal failure.