PRPH2 -associated retinal diseases (PARD) result from pathogenic PRPH2 variants, primarily affecting photoreceptor outer segments and retinal pigment epithelium. The focus of this article is to review and discuss the phenotyping of PARD subtypes.

A systematic review.

The review followed PRISMA 2020 guidelines with searches on PubMed, Medline, Web of Science, Google Scholar, and Cochrane Library. Eligible studies were those which discussed molecularly confirmed PARD or described associated diseases such as butterfly pattern dystrophy. Inclusion: cross-sectional, cohort, case-control studies, book chapters. Exclusion: non-English, conference papers, non-peer-reviewed, or non-full text articles.

PARD is responsible for 25% of pattern dystrophy and up to 5% of inherited retinal dystrophies. There is clear evidence of phenotypic variability between individuals carrying the same pathogenic variant. Fundus autofluorescence, fluorescein angiography, optical coherence tomography, while in research adaptive optics reveal detailed phenotypic characteristics, notably in retinal pigment epithelium changes and photoreceptor disruption. The phenotypic of PARD variability presents diagnostic challenges, with phenotypic features often overlapping with other retinal diseases including age-related macular degeneration, Stargardt disease, and retinitis pigmentosa.

This review emphasizes revising diagnostic criteria by incorporating more recent imaging techniques and confirming diagnosis with the use of genetic testing. Understanding phenotypic diversity and intrafamilial variability in PARD is crucial for developing new treatments and for patient prognosis and future research should focus on larger cohorts studying genotype-phenotype correlations.