RHO and retinitis pigmentosa 1: Expression of blue opsin, rhodopsin and CRX were also detected by immunocytochemistry in photoreceptor-directed fibroblasts derived from both normal healthy volunteers and EYS-RP patients (Additional file 2: Fig. S1, Figure S3 in our previous paper [26]); therefore, statistical analysis was performed on western blots for blue opsin (Additional file 2: Fig. S4).