Retinitis pigmentosa (RP) is the name given to a group of inherited conditions of the retina that all lead to a gradual progressive reduction in vision. Difficulties with night vision and peripheral (‘side’) vision are the first things that are noticed. Later, reading vision (detailed vision), colour vision, and central (‘straight-ahead’) vision are affected.
The age at which symptoms start is variable and the rate of deterioration often varies – for example with the different genetic types – but is generally very slow with changes occurring over years rather than months. In approximately half of all cases there are other family members with RP.
There are three main inheritance patterns, autosomal recessive, autosomal dominant and X-linked inheritance, depending on the genetic cause, with RP affecting approximately 1 in 3,000 to 4,000 people.
Two gene therapy trials are now ongoing in the UK for the commonest cause of X-linked RP, namely genetic faults in the RPGR gene. A third trial is anticipated to commence in 2018 in the USA.
Where mutations in the RPGR gene cause Retinitis Pigmentosa, two teams (based at University College London (UCL) and the University of Oxford) have independently developed treatments for this form of Retinitis Pigmentosa. Their respective Phase I/II trials are currently recruiting and use gene therapy to restore the RPGR gene to the photoreceptor cells in the patient’s retina. The Oxford trial has been developed in association with NightstaRx, and the UCL trial has been developed in association with MeiraGTx.
More information about the two UK trials can be obtained from:
(i) Gene Therapy for X-linked Retinitis Pigmentosa (XLRP) Retinitis Pigmentosa
(ii) A Clinical Trial of Retinal Gene Therapy for X-linked Retinitis Pigmentosa (XIRIUS)
We are grateful to Professor Michel Michaelides BSc MB BS MD FRCOphth FACS of Moorfields Eye Hospital and UCL Institute of Ophthalmology for authoring this section and the Research section of this website.