At least 29 different PDE6A mutations are known from RP patients (the human gene mutation database; http://www.hgmd.cf.ac.uk; information retrieved July 2015); thus, to understand the degenerative events in the human situation, it is necessary to come as close as possible to the defined genetic defects when we select our study material. Here, PDE6A is linked to retinitis pigmentosa 1.