Retinitis Pigmentosa (RP) can be inherited in an autosomal dominant, autosomal recessive or X-linked (XLRP) pattern, exhibiting great phenotypic and genotypic variability. 1-3 XLRP is a severe form of RP, with most affected males presenting with early-onset vision loss (<10 years of age), nyctalopia, nystagmus, severely abnormal or undetectable electroretinogram (ERG) and progression to legal blindness by the 3rd to 4th decade.4-6 RPGR and RP2 disease-causing variants are the commonest causes of XLRP, accounting for 80-90% of cases.