NM_001034853.2(RPGR):c.492G>T (p.Trp164Cys) is a missense variant that substitutes tryptophan with cysteine at amino acid 164. This variant is absent from hemizygous individuals in gnomAD v4.1.0 (PM2_Supporting). The computational predictor REVEL gives a score of 0.929, which is within the ClinGen X-linked IRD VCEP range between 0.931 to 0.773 and predicts a damaging effect on RPGR function (PP3_moderate). The computational splicing predictor SpliceAI gives a delta score of 0.08 for donor gain, which is below the ClinGen X-linked IRD VCEP threshold of >0.2 and does not predict that the variant disrupts RPGR splicing. At least one proband harboring this variant exhibits a phenotype including a family history consistent with X-linked inheritance (lacking male-to-male transmission, 2 pts) with milder phenotypes in females (1 pt), genotyping by a retinal dystrophy panel designed to detect 111 genes identifying no alternative basis for disease (2 pts), night blindness (0.5 pts), reduced best corrected visual acuity (0.5 pts), onset at age 7 years (1 pt), nonrecordable electroretinogram (required), and severe myopia (1 pt), which together are highly specific for RPGR-related retinopathy (8 pts, PMID: 30917587, PP4). The variant has been reported to segregate with retinal dystrophy through an affected mother and son from 1 family (PP1; PMID: 30917587). At least two probands harboring this variant exhibited a phenotype consistent with retinopathy, however, the required phenotypes of reduced electroretinogram responses and/or male loss of visual function before age 30 years could only be confirmed in one case, so PS4_Supporting was not met (PMID: 30718709, PMID: 30917587). In summary, this variant is classified as likely pathogenic for RPGR-related retinopathy based on the ClinGen X-linked Inherited Retinal Disease Expert Panel Specifications to the ACMG/AMP Variant Interpretation Guidelines for RPGR Version 1.0.0; PM2_Supporting, PP1, PP3_moderate, and PP4_moderate. (date of approval 05/16/2025).