Biallelic mutations in TTC21B can cause both a distinct NPHP and FSGS phenotype, which presents with HTN, proteinuria, and progressive kidney failure (Bullich et al., 2017; Huynh Cong et al., 2014), reflecting this dual phenotype affecting both the glomerular and tubulointerstitial compartment (Huynh Cong et al., 2014). Here, TTC21B is linked to focal segmental glomerulosclerosis.