Case#: Hull_2016_Patient_1.2, male, 18 years of age at onset, Irish ancestry
CasePresentingHPOs: HP:0003581 (Adult onset), HP:0007663 (Reduced visual acuity), HP:0000533 (Chorioretinal atrophy), HP:0000662 (Nyctalopia), HP:0007722 (Retinal pigment epithelial atrophy), HP:0000533 (Chorioretinal atrophy), HP:0030602 (Abnormal fundus autofluorescence imaging), HP:0000510 (Rod-cone dystrophy), HP:0008179 (Decreased Arden ratio of electrooculogram), HP:0000512 (Abnormal electroretinogram)
CaseHPOFreeText: The patient presented at age 18 with nyctalopia, progressed to central visual disturbance at age 33, and was limited to hand movement vision by age 48, with preserved peripheral vision.
CaseNotHPOs: HP:0003593 (Infantile onset), HP:0011463 (Childhood onset)
CaseNotHPOFreeText: N/A
CasePreviousTesting: Variants in REP1 and PRPH2 were initially excluded.
CaseMethod1: Candidate gene sequencing
CaseMethod2: Bidirectional, targeted Sanger sequencing within the RPE65 locus
CaseGenotypingMethod: Bidirectional Sanger sequencing of exon 13 of the RPE65 gene and flanking sequences
Variant: The patient harbors the NM_000329.3(RPE65):c.1430A>G (p.Asp477Gly) variant in one allele of RPE65.
ClinVar: 750796
gnomAD: The NM_000329.3(RPE65):c.1430A>G (p.Asp477Gly) variant was not found in gnomAD.
VariantEvidence: Exogenous expression of the variant reveals protein expression levels, cellular localization and retinoid isomerase activity comparable to the wild-type (PMID: 29659842). However, knock-in mouse models exhibit retinyl ester accumulation (PMID: 29659842), abnormally slow regeneration of 11-cis-retinal after light exposure, and ERG results indicative of delayed dark adaptation (PMID: 28041994). Mice with CRISPR-mediated knock-in of the variant also exhibit a splicing defect in RPE65 due to the introduction of a cryptic splice site, which likely triggers a frameshift, exclusion of exons 13 and 14 from the transcript, and premature truncation of the protein product (PMID: 30628748).
CaseAddInfo: N/A
CasePMIDs: N/A