NPHS2 mutations account for only 15% of Nephrotic Syndrome cases

• Grant number: 15/19955-6
• Support Opportunities: Regular Research Grants - Publications - Scientific article
• Start date: November 01, 2015
• End date: April 30, 2016
• Field of knowledge: Health Sciences - Medicine - Medical Clinics
• Principal Investigator: Maricilda Palandi de Mello
• Grantee: Maricilda Palandi de Mello
• Host Institution: Centro de Biologia Molecular e Engenharia Genética (CBMEG). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil

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 52 UTR 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 52 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: 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 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. (AU)