==== Front Ann Saudi MedAnn Saudi MedAnnals of Saudi Medicine0256-49470975-4466King Faisal Specialist Hospital and Research Centre 10.5144/0256-4947.2014.270asm-3-270aLettersReply to RE: Steroid-resistant nephrotic syndrome: impact of genetic testing Kari Jameela Abdulaziz From the Department of Pediatrics, King Abdulaziz University, Jeddah, Saudi ArabiaCorrespondence: Jameela Abdulaziz Kari, Department of Pediatrics, King Abdulaziz University, PO Box 13042 Jeddah 21943, Saudi Arabia, T: 966-505-677.904, F: 966-22-408-8353, jkari@doctors.org.ukMay-Jun 2014 34 3 270 270 Copyright © 2014, Annals of Saudi Medicine2014This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License. ==== Body We thank Dr. Muhammed Mubarak for his comments on our recent paper about the importance of genetic testing in children with steroid-resistant nephrotic syndrome (SRNS). He highlights the similarity between our results1 and their published results.2 We found that the frequency of identified disease-causing mutations in children older than 1 year with SRNS presented to KAUH was 11.4% (6.8% NPHS2 podocin gene and 4.5% NPHS1 [nephrin gene]), which was comparable to their report of 3.4% NPHS2 and 5.5% NPHS1. However, they find higher percentage of mutations (22%) in children with early onset disease, while we excluded children younger than 1 year of age in our study. The median (IQR—interquartile range age of our cohort at presentation was 3 (2.5) years with no difference between primary SRNS; 3 (2.5) years and secondary SRNS; 3 (3) years at presentation (P value .420). Regarding the timing of genetic testing, it was done after defining children as SRNS who did not respond to steroid for 4 weeks. However, the results usually arrive after a few months during which children are kept on immunsuppressions. Obtaining results takes long time as we do it as part of collaboration with Harvard medical school and previously Michigan medical school.3 Concerning the effect of including children with membranoproliferative GN (MPGN) and IgA nephropathy (IgAN) in decreasing the frequency of genetic mutations, our inclusion criteria were children with SRNS regardless the underlying renal histology. IgA nephropathy is a known underlying cause of SRNS as well as MPGN.4,5 We have reported mutations of only NPHS1, NPHS2, and WT1, and, therefore, some children with negative mutations initially were found to have other mutations such as TRPC66 or SMARCAL1.7,8 Furthermore, we believe that we have other undiscovered mutations in our area as the underlying cause of childhood SRNS. We agree with Dr. Mubarak about the need for mult-center studies of larger scale and prospective nature, to develop international guidelines on the clinical utility of genetic testing in childhood SRNS. ==== Refs REFERENCES 1 Kari JA El-Desoky SM Gari M Malik K Vega-Warner V Lovric S Bockenhauer D Steroid-resistant nephrotic syndrome: impact of genetic testing Ann Saudi Med 2013 11 33 6 533 8 24413855 2 Abid A Khaliq S Shahid S Lanewala A Mubarak M Hashmi S Kazi J Masood T Hafeez F Naqvi SA A spectrum of novel NPHS1 and NPHS2 gene mutations in pediatric nephrotic syndrome patients from Pakistan Gene 2012 7 10 502 2 133 7 22565185 3 Kari JA Bockenhauer D Stanescu H Gari M Kleta R Singh AK Consanguinity in saudi arabia: a unique opportunity for pediatric kidney research Am J Kidney Dis 2014 2 63 2 304 10 24239020 4 Cheng IK Chan KW Chan MK Mesangial IgA nephropathy with steroid-responsive nephrotic syndrome: disappearance of mesangial IgA deposits following steroid-induced remission Am J Kidney Dis 1989 11 14 5 361 4 2816928 5 Kari JA Early presentation of membranoproliferative glomerulonephritis in Arab children Saudi Med J 2003 2 24 2 157 60 12682679 6 Kari JA Jalalah S Singh A Mokhtar G Collapsing focal segmental glomerulosclerosis in a young child Nephron Clin Pract 2012 121 1–2 c83 c90 23128477 7 Safder O El-Desoky SM Bockenhauer D Sabire N Kari JA Steroid-resistant nephrotic syndrome in a child with dysmorphic features: Questions Pediatr Nephrol 2014 2 1 8 Safder O El-Desoky SM Bockenhauer D Sabire N Kari JA Steroid-resistant nephrotic syndrome in a child with dysmorphic features: Answers Pediatr Nephrol 2014 1 29