RPGR and retinitis pigmentosa 1: Most disease-causing variants in RPGR result in RP,81 but those leading to COD/CORD are preferentially sequestered at the 3’ end of the ORF15 region.82 In keeping with the majority of IRD, identical intrafamilial sequence variants in RPGR may lead to distinctly different phenotypes.83 This is exemplified by a Chinese family harbouring a 2403_04delAG deletion that resulted in both XL-RP and XL-CORD in affected men, reaffirming the importance of disease-modifying factors.84