We reasoned that the accumulation of bEF−GCAP2 at the proximal compartments of the cell rather than its absence at the rod outer segment was the cause of the progressive retinal degeneration in these mice, given that the absence of GCAP1 and GCAP2 in GCAPs−/− mice does not affect gross retinal morphology [11]. This evidence concerns the gene GUCA1A and retinal degeneration.