NM_000329.3(RPE65):c.1580A>G is a missense variant predicted to replace histidine with arginine at position 527, which is located within the active site, a well-characterized functional domain required for enzymatic activity (PM1, PMID: 34492281). This variant is present in gnomAD v.2.1.1 at an allele frequency of 0.000008877, with 1 allele / 112652 total alleles in the European non-Finnish population, which is lower than the ClinGen LCA / eoRD VCEP PM2_Supporting threshold of <0.0002 (PM2_Supporting). At least one proband harboring this variant exhibits a phenotype of retinitis pigmentosa with early childhood onset including progressive vision loss (1 pt), early onset nyctalopia (0.5 pts), severely depressed electroretinography responses from rods (0.5 pts) and cones (1 pt), tritanomaly, white retinal flecks (2 pts), retinal pigment epithelium mottling (0.5 pts), attenuated retinal vessels (0.5 pts), complete loss of peripheral fundus autofluorescence (2 pts), and outer nuclear layer thickness at the low end of the normal range, which together are highly specific for RPE65-related recessive retinopathy (total 8 pts, PMID: 17525851, PP4_Moderate). This variant has been reported in at least 1 proband with early-onset severe retinal dystrophy who was compound heterozygous with the NM_000329.3(RPE65):c.499G>T (p.Asp167Tyr) variant confirmed in trans, however, PM3 was not considered to avoid circularity (PMID: 35904185). A second proband with early-onset severe retinal dystrophy harbored the variant in the heterozygous state but was not counted for PM3 because the second variant NM_000329.3(RPE65):c.651del (p.Asp218IlefsTer3) was apparently in cis (PMID: 17525851). The computational predictor REVEL gives a score of 0.991, which is above the ClinGen LCA / eoRD VCEP threshold of ≥0.773 and predicts a damaging effect on RPE65 function (PP3_Moderate). The variant exhibited 0% enzymatic activity in a retinoid isomerase assay relative to the wild-type control, which is lower than the ClinGen LCA / eoRD VCEP PS3_Supporting threshold of <10% activity, indicating that it triggers a severe defect in protein function (PS3_Supporting, PMID: 24849605). In summary, this variant meets the criteria to be classified as likely pathogenic for RPE65-related recessive retinopathy based on the ACMG/AMP criteria applied, as specified by the ClinGen LCA / eoRD VCEP: PS3_Supporting, PM1, PM2_Supporting, PP3_Moderate, and PP4_Moderate. (VCEP specifications version 1.0.0; date of approval 09/21/2023).