NPHP1 and retinal degeneration: For instance, some common heterozygous variants in the RPGRIP1L and AHI1 genes were found to correlate to a higher occurrence of retinal degeneration in various ciliopathies and to an increased risk of NPHP1‐deleted patients to develop a more severe neurological and ophthalmological phenotype, respectively (Khanna et al., 2009; Louie et al., 2010).