In Western Europe, the most frequent genotype associated with adult FSGS consists of compound heterozygous mutations in the NPHS2 gene most often comprising the variant p.Arg229Glu (R229Q in legacy nomenclature) together with another pathogenic variant in exon 7 or 8 (15) in the NPHS2 gene in trans. This evidence concerns the gene NPHS2 and focal segmental glomerulosclerosis.