The NM_000330.4(RS1):c.276G>C variant is a missense variant encoding the substitution of Tryptophan with Cysteine at amino acid 92. This variant is absent from hemizygous individuals in gnomAD v4.1.0 (PM2_Supporting). The computational predictor REVEL gives a score of 0.982, which is above the ClinGen X-linked IRD VCEP threshold of >0.932 and predicts a damaging effect on RS1 function (PP3_strong). The computational splicing predictor SpliceAI gives a delta score of 0.00 for all predictive splice changes], which is below the ClinGen X-linked IRD VCEP threshold of >0.2 and does not predict that the variant disrupts RS1 splicing. The variant has been reported to segregate with retinal dystrophy through at least 1 meiosis in a family, which consists of 2 brothers and an unaffected mother (PP1; PMID: 9760195). At least one proband harboring this variant exhibits a phenotype including appearance of schisis and reduced visual acuity before age 13 years, which together are specific for X-linked retinoschisis (PMID: 10636421, PP4). This variant has been reported in at least 6 apparently unrelated probands meeting the PS4 requirements of a male diagnosed with X-linked retinoschisis (PMIDs: PMID: 9760195, 28348004, 31106028, 28272453, 33608557, 34624300, 39462066, and 20809529, PS4). In summary, this variant is classified as pathogenic for X-linked retinoschisis based on the ClinGen X-linked Inherited Retinal Disease Expert Panel Specifications to the ACMG/AMP Variant Interpretation Guidelines for RS1 Version 1.0.0: PM2_supporting, PP3_strong, PP1, PS4, and PP4 (date of approval 01/24/2025).