To evaluate whether variants associated with cone dystrophies in the C-terminal domain of RPGR disrupt the glutamylase activity of TTLL5, Western blot analyses were carried out in HEK293 cells co-transfected with RPGR WT/mutant constructs and TTLL5, using the GT335 antibody to detect glutamylated proteins. This evidence concerns the gene RPGR and cone dystrophy.