Exploring microperimetry and autofluorescence endpoints for monitoring disease progression in PRPF31-associated retinopathy

Background: Mutations in the splicing factor pre-messenger RNA processing factor 31 (PRPF31) gene cause autosomal dominant retinitis pigmentosa 11 (RP11) through a haplo-insufficiency mechanism. We describe the phenotype and progression of microperimetry and autofluorescence endpoints in an Indigenous Australian RP11 family. Patients and Methods: Ophthalmic examination, optical coherence tomography, fundus autofluorescence and microperimetry were performed at baseline and every 6–12 months. Baseline and annual change in best-corrected visual acuity (BCVA), microperimetry mean sensitivity (MS) and number of scotoma loci, residual ellipsoid zone (EZ) span and hyperautofluorescent ring (HAR) area were reported. Next-generation and Sanger sequencing were performed in available members. Results: 12 affected members from three generations were examined. Mean (SD, range) age at onset of symptoms was 11 (4.5, 4–19) years. MS declined steadily from the third decade and EZ span and HAR area declined rapidly during the second decade. Serial microperimetry showed negligible change in MS over 2–3 years. However, mean EZ span, near-infrared and short-wavelength HAR area reduction was 203 (6.4%) µm/year, 1.8 (8.7%) mm²/year and 1.1 (8.6%) mm²/year, respectively. Genetic testing was performed on 11 affected and 10 asymptomatic members and PRPF31 c.1205 C > A (p.Ser402Ter) mutation was detected in all affected and two asymptomatic members (non-penetrant carriers). Conclusions: Our findings suggest that in the studied cohort, the optimal window for therapeutic intervention is the second decade of life and residual EZ span and HAR area can be considered as efficacy outcome measures. Further studies on larger samples with different PRPF31 mutations and longer follow-up duration are recommended.