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).