The D126G mutation contributes to the early-onset X-linked juvenile retinoschisis.

X-linked juvenile retinoschisis (XLRS) is an inherited retinal disease caused by mutations in the RS1 gene, resulting in splitting of the retinal layers and visual disturbances. To provide insights on this disease in our cohort, genetic examination, clinical presentation, and functional analysis were performed. We observed three main RS1 mutations in our cohort of six unrelated patients: RS1-D126G, RS1-R209H, and RS1-R213W. The RS1-D126G mutation, exclusively reported in Thai patients so far, showed the highest prevalence. Phenotypically, the D126G mutation manifested early (0.3-4 years old), presenting as asymmetrical visual acuity and schisis. Functional analysis revealed that the molecular pathomechanism of D126G was the failure of protein secretion attributable to endoplasmic reticulum retention. The understanding of the genotype-phenotype relationship and the pathomechanisms of specific mutations in a particular population could immensely benefit the pipeline of personalised treatment design for XLRS.