BACKGROUND: Mutations in INF2 are frequently responsible for focal segmental glomerulosclerosis (FSGS), which is a common cause of end stage renal disease (ESRD); additionally, they are also connected with Charcot-Marie-Tooth neuropathy. INF2 encodes for inverted formin 2. This protein participates in regulation of the dynamics of the actin cytoskeleton, involving not only the polymerisation, but also the depolymerisation of filaments. The present study is the first mutational analysis of INF2 done in the Czech Republic. METHODS: Mutational analysis of INF2 was performed on 109 patients (mean age at onset 41.44 ± 18.91 years) with FSGS or minimal change disease (MCD); and also in 6 patients without renal biopsy who had already developed chronic kidney disease (CKD)/ESRD at the time of diagnosis. We used high resolution melting method (HRM), with subsequent Sanger sequencing, in suspect samples from HRM analysis. The HRM method is an effective method for the screening of large cohorts of patients. RESULTS: Two pathogenic mutations (p.Arg214His and p.Arg218Gln) were detected in INF2. The first (p.Arg214His) was identified in the FSGS patient with a positive family history. The second mutation (p.Arg218Gln) was found in two brothers with ESRD of unknown etiology. The most frequent sequence change was the substitution p.P35P, the incidence of which corresponded with the frequencies available in the ExAC Browser and gnomAD Browser databases. This analysis also detected different exonic and intronic changes that probably did not influence the phenotype of the included patients. CONCLUSIONS: The INF2 mutational screening is useful in familial FSGS cases as well as in patients with an unknown cause for their ESRD, but with a positive family history. INF2 seems to be not only the cause of FSGS, but also of ESRD of unknown etiology. Our study has confirmed that the HRM analysis is a very useful method for the identification of single nucleotide substitutions.

Department of Clinical and Transplant Pathology Institute for Clinical and Experimental Medicine Prague Czech Republic

Department of Nephrology 1st Faculty of Medicine Charles University and General University Hospital Prague Prague Czech Republic

Institute of Biology and Medical Genetics 1st Faculty of Medicine Charles University and General University Hospital Prague Prague Czech Republic

Reprofit International Brno Czech Republic

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D’Agati VD, Fogo AB, Bruijn JA, Jennette JC. Pathologic classification of focal segmental glomerulosclerosis: a working proposal. Am J Kidney Dis. 2004;43:368–382. doi: 10.1053/j.ajkd.2003.10.024. PubMed DOI

Howie AJ. Pathology of minimal change nephropathy and segmental sclerosing glomerular disorders. Nephrol Dial Transplant. 2003;18:vi33–vi38. doi: 10.1093/ndt/gfg1061. PubMed DOI

Becker DJ. Minimal change disease. Nephrology Rounds. 2008;6:304–066.

Kaplan JM, Kim SH, North KN, Rennke H, Correia LA, Tong HQ, et al. Mutations in ACTN4, encoding α-actinin-4, cause familial focal segmental glomerulosclerosis. Nat Genet. 2000;24(3):251–256. doi: 10.1038/73456. PubMed DOI

Brown EJ, Schlöndorff JS, Becker DJ, Tsukaguchi H, Tonna SJ, Uscinski AL, et al. Mutations in the formin gene INF2 cause focal segmental glomerulosclerosis. Nat Genet. 2010;42(1):72–76. doi: 10.1038/ng.505. PubMed DOI PMC

Winn MP, Conlon PJ, Lynn KL, Farrington MK, Creazzo T, Hawkins AF, et al. A mutation in the TRPC6 cation channel causes familial focal segmental glomerulosclerosis. Science. 2005;308(5729):1801–1804. doi: 10.1126/science.1106215. PubMed DOI

Chhabra ES, Higgs HN, et al. INF2 is a WASP homology 2 motif-containing formin that severs actin filaments and accelerates both polymerization and depolymerization. J Biol Chem. 2006;281(36):26754–26767. doi: 10.1074/jbc.M604666200. PubMed DOI

Schönichen A, Geyer M. Fifteen formins for an actin filament: a molecular view on the regulation of human formins. BBA-Mol Cell Res. 2010;1803(2):152–163. PubMed

Barua M, Brown EJ, Charoonratana VT, Genovese G, Sun H, Pollak MR. Mutations in the INF2 gene account for a significant proportion of familial but not sporadic focal and segmental glomerulosclerosis. Kidney Int. 2013;83(2):316–322. doi: 10.1038/ki.2012.349. PubMed DOI PMC

Boyer O, Nevo F, Plaisier E, Funalot B, Gribouval O, Benoit G, et al. INF2 mutations in Charcot-Marie-tooth disease with glomerulopathy. N Engl J Med. 2011;365(25):2377–2388. doi: 10.1056/NEJMoa1109122. PubMed DOI

Yates A, Akanni W, Amode MR, Barrell D, Billis K, Carvalho-Silva D, et al. Ensembl 2016. Nucleic Acids Res. 2016;44(Database issue):D710–D716. doi: 10.1093/nar/gkv1157. PubMed DOI PMC

Schwarz JM, Cooper DN, Schuelke M, Seelow D. MutationTaster2: mutation prediction for the deep-sequencing age. Nat Methods. 2014;11(4):361–362. doi: 10.1038/nmeth.2890. PubMed DOI

Adzhubei IA, Schmidt S, Peshkin L, Ramensky VE, Gerasimova A, Bork P, et al. A method and server for predicting damaging missense mutations. Nat Methods. 2010;7(4):248–249. doi: 10.1038/nmeth0410-248. PubMed DOI PMC

Choi Y, Sims GE, Murphy S, Miller JR, Chan AP. Predicting the Functional Effect of Amino Acid Substitutions and Indels. PLoS One. 2015;7(10):e46688. doi: 10.1371/journal.pone.0046688. PubMed DOI PMC

Ng PC, Henikoff S. Predicting deleterious amino acid substitutions. Genome Res. 2001;11(5):863–874. doi: 10.1101/gr.176601. PubMed DOI PMC

Desmet FO, Hamroun D, Lalande M, Collod-Béroud G, Claustres M, Béroud C. Human splicing finder: an online bioinformatics tool to predict splicing signals. Nucleic Acids Res. 2009;37(9):e67. doi: 10.1093/nar/gkp215. PubMed DOI PMC

Caridi G, Lugani F, Dagnino M, Gigante M, Iolascon A, Falco M, et al. Novel INF2 mutations in an Italian cohort of patients with focal segmental glomerulosclerosis, renal failure and Charcot-Marie-Tooth neuropathy. Nephrol Dial Transplant. 2014;29(Suppl 4):iv80–iv86. doi: 10.1093/ndt/gfu071. PubMed DOI

Boyer O, Benoit G, Gribouval O, Nevo F, Tête MJ, Dantal J, et al. Mutations in INF2 are a major cause of autosomal dominant focal segmental glomerulosclerosis. J Am Soc Nephrol. 2011;22(2):239–245. doi: 10.1681/ASN.2010050518. PubMed DOI PMC

Gigante M, Caridi G, Montemurno E, Soccio M, d’Apolito M, Cerullo G, Messina G. TRPC6 mutations in children with steroid-resistant nephrotic syndrome and atypical phenotype. Clin J Am Soc Nephrol. 2011;6(7):1626–1634. doi: 10.2215/CJN.07830910. PubMed DOI