PAX6-associated aniridia and RPGR-related X-linked retinitis pigmentosa: a rare dual Mendelian molecular diagnosis.

An exceptionally rare case of dual Mendelian molecular diagnosis is presented in a young male with both PAX6-associated congenital aniridia and RPGR-related X-linked retinitis pigmentosa. The patient presented in childhood with photophobia, iris hypoplasia, foveal hypoplasia on optical coherence tomography and reduced multifocal electroretinography amplitude, consistent with PAX6-related aniridia confirmed by familial variant testing. In early adulthood, progressive nyctalopia, visual field constriction and widespread peripheral pigmentary retinopathy emerged. Whole-exome sequencing revealed a second pathogenic variant in RPGR, establishing a dual diagnosis. This case underscores that atypical or complex ocular phenotypes may reflect co-occurrence of independent genetic disorders. Comprehensive anterior and posterior phenotyping combined with broad genetic testing optimises diagnostic yield. Management requires lifelong multidisciplinary follow-up addressing each condition separately, plus genetic counselling to clarify distinct inheritance patterns (PAX6: autosomal dominant; RPGR: X-linked).