ABSTRACT. Mutations in the Wilms' tumor suppressor gene (WT1) can lead to syndromic forms of steroid-resistant nephrotic syndrome (SRNS) such as Denys-Drash or Frasier syndrome and can cause isolated SRNS. A mutation within WT1 is a frequent cause of sporadic isolated SRNS in girls. In a worldwide cohort of girls, the rate of occurrence was 10.8%. Previous reports have indicated that in Chinese girls, the detection rate of WT1 mutations is 16.7% for early onset isolated nephrotic syndrome. The detection rate of WT1 mutations in Chinese girls with sporadic isolated SRNS is unknown. We examined WT1 mutations in 14 Chinese girls with sporadic isolated SRNS using polymerase chain reaction and direct sequencing and studied a control group of 38 boys with sporadic isolated SRNS. We identified a WT1 mutation in 1 of 14 (7.1% detection rate) Chinese girls with sporadic 6185 ©FUNPEC-RP www.funpecrp.com.br Genetics and Molecular Research 12 (4): 6184-6191 (2013) WT1 mutations in sporadic isolated SRNS isolated SRNS. No mutations occurred in WT1 in the remaining 13 girls or the control group. Our investigation supports the necessity of genetic examination for mutations in WT1 in girls with sporadic isolated SRNS.

Mutations in the WT1 gene can lead to Denys-Drash syndrome or Frasier syndrome and can also cause isolated nephrotic syndrome (NS). Most patients with isolated NS caused by WT1 mutations present as 46, XX phenotypic females. There have been two cases with an onset age younger than 3 years with isolated NS caused by WT1 mutations presenting as 46, XY phenotypic males. We present a 46, XY phenotypic male patient with isolated NS and end-stage renal disease (ESRD) at the age of 6.3 years. He had normal male external genitalia with normal penis length and soft and normal volume of both testes. A mutation, 1051A>G (K351E), in exon 8 of WT1 was identified in the patient. After starting hemodialysis, manifestations of hypertension and renal failure improved, but he died at 6.8 years of age as a result of respiratory failure and heart failure. Our study supports the necessity of searching for mutations in WT1 in 46, XY phenotypic male patients with isolated NS and ESRD.

BackgroundHemophagocytic lymphohistiocytosis (HLH) is a rare, life-threatening disorder characterized by prolonged fever, cytopenia, hepatosplenomegaly, rash, icterus, and other neurological symptoms. Successful treatment of HLH by etoposide has improved outcomes for children with HLH. However, the development of treatment-related acute myeloid leukemia (t-AML) after the usage of this drug is a concern.Case presentationWe report a case of acquired EBV-triggered HLH with progression to t-AML following etoposide therapy with cytogenetic abnormality for t (11; 19) (q23; p13) resulting in MLL gene fusion. The development of t-AML was detected 23 months after HLH diagnosis.ConclusionsAlthough the successful treatment of HLH by etoposide has improved outcomes for children with HLH, t-AML is a serious complication of topoisomerase II inhibitor therapy and is characterized by the presence of gene rearrangement. This study suggests that HLH patients undergoing therapy with HLH-2004 protocol need monitoring for future malignancy, especially in the initial 2 to 3 years.

ABSTRACT. Recent studies have demonstrated that mutations in 4 podocyte genes, NPHS1, NPHS2, CD2AP, and WT1, are associated with the pathogenesis of steroid-resistant nephrotic syndrome (SRNS). Systematic investigation of all 4 genes for sporadic SRNS in China has not been performed. We examined 10 Chinese children with sporadic SRNS who showed no response to immunosuppressive agents and 20 SRNS controls who exhibited a response to prolonged steroid or immunosuppressive treatment and achieved complete remission. We analyzed mutations in the 4 podocyte genes, NPHS1, NPHS2, CD2AP, and WT1. Mutational analysis was performed using polymerase chain reaction and direct sequencing. Of the 10 SRNS children who showed no response to immunosuppressive agents, the compound heterozygous NPHS1 mutations 2677A>G (T893A) 9515©FUNPEC-RP www.funpecrp.com.br Genetics and Molecular Research 13 (4): 9514-9522 (2014) Podocyte gene mutations in SRNS and *142T>C were identified in 1 patient, while a heterozygous mutation in WT1, 1180C>T (R394W), was found in another patient. Of the 20 SRNS children showing complete remission who responded to prolonged steroid therapy or immunosuppressive agents, 4 heterozygous NPHS1 mutations, 928G>A, IVS8+30C>T, IVS21+14G>A, and IVS25-23C>T, were identified in 4 patients and a heterozygous CD2AP mutation, IVS7-135G>A, was identified in 1 patient. Our results indicate the necessity of genetic examination for mutations in podocyte genes in Chinese SRNS children who show no response to immunosuppressive agents.

Mutations in the WT1 gene, leading to Denys-Drash syndrome and Frasier syndrome, can also cause isolated steroid-resistant nephrotic syndrome (ISRNS). Previous studies have reported six pairs of monozygotic twins with WT1 mutations, including one presenting with discordant phenotypes with identical WT1 mutations being of paternal origin and five pairs of monozygotic twins presenting the same phenotype with identical WT1 mutations. In this study, we report on female monozygotic twins showing discordant phenotypes with an identical de novo WT1 mutation, R394W, and presenting incomplete Denys-Drash syndrome and ISRNS.