NPHP1 and retinal degeneration: Strikingly, one of the AHI1 variants they described as a potential modifier for neurological involvement in patients with NPHP1 mutations, p.Arg830Trp, was recently identified as a modifier allele for retinal degeneration in patients with NPHP, independent of a primary NPHP1 mutation (Louie et al., 2010).