Abstract
Purpose :
There have been case reports of individual families with cone/cone-rod phenotype (C/CRD) due to mutations in the C-terminus (3' end) of ORF15 in RPGR. Based on this information, we sought to describe the phenotype of our patient cohort with mutations in this region.
Methods :
A retrospective chart review of patients with known mutations in 3' ORF15 (>AA 950) was performed. Information was collected on age of onset, visual acuity, visual field, ERG, and fundus findings. The same data was also collected on age-matched patients with non-3’ ORF15 mutations in RPGR.
Results :
Clinical data on 4 children (range 6-11, avg. 8.8 years) and 8 adults (range 26-51, avg. 36.4) with 3' mutations were analyzed. This was compared with data of 6 children (range 6-11, avg. 8.5 years) and 8 adults (range 28-53, avg. 36.9 years) with mutations elsewhere in ORF15. The majority (75%) of patients with 3' mutations had a diagnosis of a C/CRD, and 25% had a diagnosis of RP. Seven out of eight (87.5%) reported photosensitivity, 5/10 (50%) reported nightblindness, and all had color vision abnormalities. While 25% had a childhood onset, 58% were identified as adults, and 2 children were asymptomatic at the time of diagnosis. Five individuals (42%, all adults) had visual acuity <20/200. The most common visual field finding was a central/paracentral scotoma (found in 42%), but 2 children had normal fields. The most common retinal findings were macular/peripapillary atrophy and retinal granularity. Bone spicules/pigment clumps were only found in 16% of this cohort. Among the group with non-3' end mutations, 2 had been diagnosed with CRD and the remainder with RP. Overall, this group had a trend towards an earlier age of onset: 7/12 (58%) had symptoms in childhood, 1/12 in their teens, and 4/12 as adults. One child was asymptomatic. In the comparison cohort, only 1 adult had visual acuity <20/200, but 58% (including one child) had a constriction of their visual field to <20 degrees. Bone spicules were found in 57%.
Conclusions :
Among patients with ORF15 mutations, patients with 3' mutations primarily had a C/CRD, but some also had an RP phenotype. Moreover, several of the patients with 3’ mutations had a trend towards a later onset when compared with patients with mutations elsewhere in ORF15. These phenotypic features are important to consider when evaluating patients with C/CRD and RP in the clinic setting to better predict the molecular cause of disease for these patients.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.