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Genotype-Phenotype Correlations in RPGRIP1-Associated Retinal Dystrophy in a Nationwide Japanese Cohort.
Kei Mizobuchi1, Taiga Inooka2, Takuya Aoki3
1From the Department of Ophthalmology (K.M., T.N., T.H.), The Jikei University School of Medicine, Minato-ku, Tokyo, Japan.
American Journal of Ophthalmology
|May 8, 2026
Summary
RPGRIP1 gene variants cause distinct retinal dystrophies, Leber congenital amaurosis (LCA) and achromatopsia (ACHM), in Japanese patients. Specific genetic variants correlate with disease type and progression, aiding diagnosis and counseling.
Area of Science:
- Ophthalmology
- Genetics
- Medical Research
Background:
- Retinal dystrophies are a group of inherited eye diseases.
- RPGRIP1 gene mutations are a known cause of certain retinal dystrophies.
- Understanding genotype-phenotype correlations is crucial for diagnosis and treatment.
Purpose of the Study:
- To investigate genotype-phenotype correlations in Japanese patients with RPGRIP1-associated retinal dystrophy.
- To differentiate clinical features between Leber congenital amaurosis (LCA) and achromatopsia (ACHM) caused by RPGRIP1 variants.
- To identify prevalent RPGRIP1 variants in the Japanese population.
Main Methods:
- Retrospective, multicenter cohort study of Japanese patients with RPGRIP1 variants.
- Genetic analysis including PCR for exon 18 deletion (exon 18-DEL), whole-exome, and whole-genome sequencing.
- Ophthalmic evaluations: visual acuity, visual fields, electroretinography (ERG), and multimodal retinal imaging.
Main Results:
- Thirty-four patients (23 with ACHM, 11 with LCA) from 26 families were analyzed.
- Exon 18-DEL was the most common RPGRIP1 variant (63.2%).
- LCA patients had worse visual acuity and earlier vision loss than ACHM patients, with distinct ERG and imaging findings.
Conclusions:
- RPGRIP1 variants lead to distinct LCA and ACHM phenotypes with clear genotype-phenotype correlations.
- The exon 18-DEL variant may be a founder mutation in Japan.
- Findings improve understanding of RPGRIP1-associated retinal dystrophy, aiding diagnosis, prognosis, and therapy development.
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