The Trajectory of Gene Discovery in Retinitis Pigmentosa

Background: To assess how historical patterns in retinitis pigmentosa (RP) gene inheritance, functional category, and phenotypic onset may inform the remaining unsolved RP discovery space. Methods: We manually reviewed PubMed-indexed primary reports in the RetiGene database, supplemented with PubMed-indexed human studies where necessary to improve extractable phenotype data. Gene-level variables extracted included age of symptom onset, inheritance pattern, functional category and syndromic association. Gene-level associations between earliest year of RP gene discovery and mean age of symptom onset were assessed, alongside temporal analyses for functional category, inheritance, and syndromic patterns. Results: Later year of gene discovery was associated with later mean age of symptom onset, both in the primary analysis restricted to genes with at least 5 extractable onset cases (n = 83, p < 0.001) and in a stricter sensitivity analysis restricted to genes with at least 10 onset cases (n = 66, p = 0.00525). Year of discovery differed significantly across functional categories (p < 0.001). No significant temporal association was observed for AR versus non-AR inheritance or syndromic status. Conclusions: This hypothesis-generating analysis suggests that observed patterns likely reflect a combination of biological detectability, study design, and publication dynamics rather than intrinsic gene-phenotype relationships alone; within this context, future RP-solving efforts may benefit from greater attention to less obvious biological pathways (such as ciliary, transport, and metabolic categories), along with later-presenting or less conspicuous phenotypes.