Possible digenic inheritance with INVS [40];A heterozygous NPHP4 variant may modify compound heterozygous NPHP3 with early-onset ESKD and hepatic fibrosis [40,43];In patients with syndromic nephronophthisis caused by several genes (including NPHP3, IQCB1, CEP290, and MKS1), an additional heterozygous variant in RPGRIP1L is associated with retinitis pigmentosa [44]. Here, NPHP4 is linked to retinitis pigmentosa.