NPHP4 and ciliopathy: RPGRIP1, RPGRIP1L and NPHP4 are integral constituents of the NPHP TZ module and were shown previously to harbour distinct RPGRIP1N-C2 type domains27 that are important for their mutual interaction and mutated in ciliopathies such as JBTS, NPHP and Leber congenital amaurosis29, 30.