PRESENTING AUTHOR

To present the 6-year follow-up of two siblings exhibiting drastically different phenotypes despite identical c.305 G>A p.Arg102Gln RS1 mutations.

Sibling 1: 13-year-old male initially referred to Duke Eye Center at age 7 with X-Linked Retinoschisis (XLRS) complicated by vitreous hemorrhage. Initial best-corrected visual acuity (BCVA) was 20/200 OD and 20/100 OS. Retinal examination revealed vitreous hemorrhage OD, foveal and peripheral schisis (with no schisis detachment) OU. Spectral domain optical coherence tomography (SD-OCT) revealed central foveal thickness (CFT) of 778 μm OD and 589 μm OS. Vitreous hemorrhages recurred at ages 11 and 12 in OD. During his last visit (age 13) findings revealed no vitreous hemorrhage, significant foveal schisis reduction (CFT 143 μm OD, 168 μm OS) and BCVA of 20/60 OU. Peripheral schisis remained stable.

Sibling 2: 11-year-old male initially referred to Duke Eye Center as a 5-year-old with XLRS and no visual complains (BCVA 20/50 OD, 20/40 OS). Fundus examinations since baseline appeared normal except for a blunted foveal reflex and discrete vitreous debris (no vitreous hemorrhage was observed in 6 years of follow-up). CFT has remained stable with discrete foveal intraretinal cysts (229.8±1.09 μm OD and 223.5±3.20 μm OS). BCVA of 20/30 OU during his last 3 visits.

Our findings support existing publications describing high phenotypic variability (including the presence of vitreous hemorrhage and CFT thickening) among patients with identical RS1 mutation variants. This has important implications for prognosis and counseling.

High phenotypic variability exists among patients with identical RS1 mutation variants.