NPHP1 and retinal degeneration: For instance, the homozygous deletion of a 290 kb genomic region on chromosome 2 encompassing the entire NPHP1 gene is known to cause a spectrum of phenotypes ranging from isolated NPHP to congenital OMA (although no neuroimaging data of these patients were available) to JS with or without NPHP and retinal degeneration (Betz et al., 2000; Castori et al., 2005; Parisi et al., 2004).