Eight-year follow-up of phenotypic progression in a Chinese XLRP pedigree with a novel RP2 gene mutation.

BACKGROUND

This study characterizes a Chinese X-linked retinitis pigmentosa (XLRP) pedigree harboring a pathogenic variant of the RP2 gene and presents the findings from 8-years follow-up with the aim of exploring the genotypic and phenotypic spectra.

METHODS

We collected data from a Chinese pedigree comprising 23 individuals, including six affected males and five female carriers; all individuals underwent molecular analyses and comprehensive ophthalmic evaluations.

RESULTS

We identified a novel c.392G>A (p.C131Y) mutation of the RP2 gene. The baseline clinical evaluations of four affected males in the average age range of 1-8 years showed visual impairment; the mean visual acuity had a logMAR value of 0.5235 (range: 0.301-0.698) with an average spherical equivalent of -4.15D (range: -3.125D to -6.25D). The funduscopic observations were consistent with typical X-linked retinoschisis presentations, including pigmentary abnormalities, tessellated changes, and yellowish-white punctate exudations. We also detected disorganization of the outer retinal layer and decline of the electroretinography (ERG) amplitudes. Meanwhile, the five heterozygous carriers showed a wide range of phenotypic variability accompanied by mild or moderate visual changes. Intriguingly, asymmetric changes of the fundus were also detected in the retina of one of the carriers. During the 8-year follow-up period, the visual acuity remained unchanged or even improved slightly. Although early-onset myopia was more common in children, there was a slightly increasing trend in annual progression; moreover, while the retinal structure did not differ statistically significantly, the ERG changes indicated a steadily decreasing trend.

CONCLUSION

The findings of this study provide insights into the pathogenicity of RP2-related XLRP, expand the spectrum of disease mutations, and enrich knowledge regarding the clinical phenotypes while highlighting the progressive nature and phenotypic variability.