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For disorders with X-linked inheritance, variants may be transmitted through multiple generations of carrier females before an affected male is ascertained. Pathogenic RS1 variants exclusively cause X-linked retinoschisis (XLRS). While RS1 is constrained to variation, recurrent variants are frequently observed in unrelated probands. Here, we investigate recurrent pathogenic variants to determine the relative burden of mutational hotspot and founder allele events to this phenomenon. A cohort RS1 variant analysis and standardized classification, including variant enrichment in the XLRS cohort and in RS1 functional domains, were performed on 332 unrelated XLRS probands. A total of 108 unique RS1 variants were identified. A subset of 19 recurrently observed RS1 variants were evaluated in 190 probands by a haplotype analysis, using microsatellite and single nucleotide polymorphisms. Fourteen variants had at least two probands with common variant-specific haplotypes over ~1.95 centimorgans (cM) flanking RS1. Overall, 99/190 of reportedly unrelated probands had 25 distinct shared haplotypes. Examination of this XLRS cohort for common RS1 haplotypes indicates that the founder effect plays a significant role in this disorder, including variants in mutational hotspots. This improves the accuracy of clinical variant classification and may be generalizable to other X-linked disorders.

Purpose To explore the experiences of parents of sons with X-linked retinoschisis (XLRS). Design Mixed methods—qualitative interviews with quantitative survey. Methods Parents of sons with XLRS who were evaluated at the National Eye Institute between December 2017 and January 2019 were eligible for this study. Participation involved engaging in a semistructured interview and completing a survey assessing optimism, anxiety, personality traits, and sociodemographics using valid and reliable scales. Interview transcripts were coded and analyzed thematically, and scales were scored and used descriptively. Results Eleven mothers and 8 fathers from 13 families participated. Optimism, anxiety, and personality traits fell into the normative ranges for the scales. Parents described a process of continuous adaptation to their son's condition. The initial diagnosis was characterized by shock, grief, and “devastation” for most parents. Maternal guilt was common, but usually lessened over time. As parents adjusted to life postdiagnosis, they attempted to achieve a state of normalcy while balancing a desire to protect their sons. Significant sources of stress included decisions around sports participation and driving. Among all parents, the fear of retinal detachment was an ongoing concern. Most parents did identify perceived benefits from their experiences, such as feelings of gratitude or family cohesion. Conclusions Most parents viewed XLRS as a significant challenge in their sons' lives, but one that could be overcome. Clinical encounters may be enhanced for families with XLRS by providing accurate information, preparing families for potential challenges, anticipating stressful decisions, and meeting other families with XLRS.