title: NPHS2 mutations account for only 15% of nephrotic syndrome cases.
abstract: BACKGROUND
  Nephrotic syndrome is traditionally classified on the basis of the response to standard steroid treatment. Mutations in more than 24 genes have been associated with nephrotic syndrome in children, although the great majority of steroid-resistant cases have been attributed to mutations in three main genes: NPHS1, NPHS2 and WT1. The aims of this study were to identify mutations in these genes more frequently reported as mutated and to characterize each variation using different in silico prediction algorithms in order to understand their biological functions.
  
  
  METHODS
  We performed direct sequence analysis of exons 8 and 9 of WT1, 8 exons of NPHS2 and 29 exons of NPHS1, including NPHS2 and NPHS1 intron-exon boundary sequences, as well as 700 bp of the 5' UTR from both genes in 27 steroid-resistant patients aged between 3 months and 18 years.
  
  
  RESULTS
  Analysis of the NPHS2 gene revealed four missense mutations, one frameshift mutation and three variations in the 5' UTR. Four patients presented compound heterozygosis, and four other patients presented one heterozygous alteration only. WT1 and NPHS1 gene analysis did not reveal any mutations.
  
  
  CONCLUSIONS
  This is the first study focusing on genetics of SRNS in Brazilian children. Identification of mutations is important because it could influence physicians' decision on patient treatment, as patients carrying mutations can be spared the side effects of immunosuppressive therapy and ultimately could be considered for kidney transplantation from a living donor.
  
  
  CONCLUSIONS
  After molecular analysis of the genes more frequently reported as mutated in 27 steroid-resistant nephrotic syndrome patients, we identified NPHS2 mutations confirming the hereditary character of the kidney disease in only 14.8% of patients. Therefore, the next step is to perform a next generation sequencing based analysis of glomeluropathy-related panel of genes for the remaining patients in order to search for mutations in other genes related to steroid-resistant nephrotic syndrome.
authors.affiliation: Centro de Biologia Molecular e Engenharia Genética, Universidade Estadual de Campinas, Campinas, São Paulo, Caixa Postal 6010, Brasil. mara.guaragna@gmail.com.
authors.forename: Mara Sanches
authors.initials: MS
authors.lastname: Guaragna
authors.affiliation: Nefrologia Pediátrica, Departamento de Pediatria, Faculdade de Ciências Médicas, Universidade Estadual de Campinas, Campinas, São Paulo, Brasil. aclutaif@uol.com.br.
authors.forename: Anna Cristina G B
authors.initials: AC
authors.lastname: Lutaif
authors.affiliation: Centro de Biologia Molecular e Engenharia Genética, Universidade Estadual de Campinas, Campinas, São Paulo, Caixa Postal 6010, Brasil. cristianepiveta@yahoo.com.br.|Centro de Investigação em Pediatria, Faculdade de Ciências Médicas, Universidade Estadual de Campinas, Campinas, São Paulo, Brasil. cristianepiveta@yahoo.com.br.
authors.forename: Cristiane S C
authors.initials: CS
authors.lastname: Piveta
authors.affiliation: Centro de Biologia Molecular e Engenharia Genética, Universidade Estadual de Campinas, Campinas, São Paulo, Caixa Postal 6010, Brasil. malopes.souza@gmail.com.
authors.forename: Marcela L
authors.initials: ML
authors.lastname: Souza
authors.affiliation: Centro de Biologia Molecular e Engenharia Genética, Universidade Estadual de Campinas, Campinas, São Paulo, Caixa Postal 6010, Brasil. suellen.souza05@gmail.com.
authors.forename: Suéllen R
authors.initials: SR
authors.lastname: de Souza
authors.affiliation: Centro de Biologia Molecular e Engenharia Genética, Universidade Estadual de Campinas, Campinas, São Paulo, Caixa Postal 6010, Brasil. tacianebh@gmail.com.
authors.forename: Taciane B
authors.initials: TB
authors.lastname: Henriques
authors.affiliation: Departamento de Genética Médica, Faculdade de Ciências Médicas, Universidade Estadual de Campinas, Campinas, São Paulo, Brasil. atmg@uol.com.br.|Grupo Interdisciplinar de Estudos da Determinação e Diferenciação do Sexo, Faculdade de Ciências Médicas, Universidade Estadual de Campinas, Campinas, São Paulo, Brasil. atmg@uol.com.br.
authors.forename: Andréa T
authors.initials: AT
authors.lastname: Maciel-Guerra
authors.affiliation: Nefrologia Pediátrica, Departamento de Pediatria, Faculdade de Ciências Médicas, Universidade Estadual de Campinas, Campinas, São Paulo, Brasil. vmsbelangero@gmail.com.
authors.forename: Vera M S
authors.initials: VM
authors.lastname: Belangero
authors.affiliation: Centro de Investigação em Pediatria, Faculdade de Ciências Médicas, Universidade Estadual de Campinas, Campinas, São Paulo, Brasil. gileandrea@uol.com.br.|Grupo Interdisciplinar de Estudos da Determinação e Diferenciação do Sexo, Faculdade de Ciências Médicas, Universidade Estadual de Campinas, Campinas, São Paulo, Brasil. gileandrea@uol.com.br.|Endocrinologia Pediátrica, Departamento de Pediatria, Faculdade de Ciências Médicas, Universidade Estadual de Campinas, Campinas, São Paulo, Brasil. gileandrea@uol.com.br.
authors.forename: Gil
authors.initials: G
authors.lastname: Guerra-Junior
authors.affiliation: Centro de Biologia Molecular e Engenharia Genética, Universidade Estadual de Campinas, Campinas, São Paulo, Caixa Postal 6010, Brasil. mpmello869@gmail.com.
authors.forename: Maricilda P
authors.initials: MP
authors.lastname: De Mello
mesh_terms: D020121:5' Untranslated Regions / Q000235:genetics*; D000293:Adolescent; D001483:Base Sequence; D002648:Child; D002675:Child, Preschool; D019295:Computational Biology; D017931:DNA Primers / Q000235:genetics; D016368:Frameshift Mutation / Q000235:genetics; D006801:Humans; D007223:Infant; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics*; D008565:Membrane Proteins / Q000235:genetics*; D008969:Molecular Sequence Data; D020125:Mutation, Missense / Q000235:genetics; D009404:Nephrotic Syndrome / Q000235:genetics*; D017422:Sequence Analysis, DNA; D025721:WT1 Proteins / Q000235:genetics
chemical_list: D020121:5' Untranslated Regions; D017931:DNA Primers; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; C407223:NPHS2 protein; D025721:WT1 Proteins; C583751:WT1 protein, human; C113267:nephrin