Adult‐Onset Nephrotic Syndrome due to a Homozygous <i>TNS2</i> Truncating Variant: Broadening the Mutational Spectrum

TNS2-related Nephrotic Syndrome (TNS2-NS) is a rare form of nephrotic syndrome inherited in an autosomal recessive manner, caused by pathogenic variants in the TNS2 gene. Only five cases have been documented, all involving biallelic missense variants with symptoms appearing in early childhood. We describe a 34-year-old man with nephrotic syndrome who was found to have a homozygous stop-gain mutation in TNS2 via exome sequencing. This is the first reported human case with a truncating TNS2 variant and adult-onset disease, differing from earlier cases with early onset and missense mutations. While studies in mice show that Tns2 is vital for kidney health, similar human data are lacking. Our results indicate that null mutations in TNS2 could also lead to nephrotic syndrome and may result in the disease manifesting later in life.