Regional differences in genes and variants causing retinitis pigmentosa in Japan

Relationships between causative genes and epiretinal membrane formation in Japanese patients with retinitis pigmentosa

PURPOSE

To investigate the relationships between macular complications and causative genes frequently found in Japanese patients with retinitis pigmentosa (RP).

METHODS

In the retrospective and observational study, we analyzed the data of 75 patients with RP (EYS-RP: 42 patients; USH2A-RP: 19 patients; RHO-RP: 14 patients) who were followed-up at Kyushu University Hospital and whose causative genes had been identified. Macular complications including epiretinal membrane (ERM), macular edema (ME), and macular hole (MH) were evaluated using optical coherence tomography and fundus photography. Main outcome was the proportion of macular complications.

RESULTS

The proportion of ERM was 35.7% in the EYS group, 10.5% in the USH2A group and 14.3% in the RHO group. The proportion of ME was 7.1% in the EYS group, 5.3% in the USH2A group and 14.3% in the RHO group, and that of MH was 2.4% in the EYS group, 5.3% in the USH2A group and 0% in the RHO group. In the EYS group, the proportion of ERM was relatively higher (p = 0.06), and the presence of EYS was significantly associated with a higher age- and sex-adjusted OR for ERM (OR = 5.67, 95% CI = 1.59-25.20). There was no significant difference in the proportion of MH or ME among causative genes.

CONCLUSIONS

EYS causative gene may be associated with higher rate of ERM complication in RP.

Genotypes and clinical features of RHO-associated retinitis pigmentosa in a Japanese population

PURPOSE

To report the genotypes and clinical features of RHO-associated retinitis pigmentosa (RHO-RP) in the Kyushu region of Japan.

STUDY DESIGN

Retrospective, single-center study.

METHODS

Sixteen RP patients with pathogenic RHO variants seen at Kyushu University Hospital were investigated. Clinical data including age, best-corrected visual acuity (BCVA) in logarithm of the minimum angle of resolution (logMAR) units, visual field, fundus photography, and optical coherence tomography were retrospectively obtained. Visual outcomes were compared between classical and sector phenotypes and among genetic variants.

RESULTS

The mean age at the first visit was 54.0 ± 15.7 years, with a mean follow-up of 7.6 ± 4.0 years. Fourteen patients (87.5%) showed the classical RP phenotype, of whom four were associated with p.[Pro23Leu] and two had p.[Pro347Leu] variants. In addition, two patients with the sector phenotype harbored p.[Ala164Val] variants. Among the classical RHO-RP patients, the mean BCVA decreased from 0.60 to 1.08 logMAR over the follow-up period (7.4 ± 4.1 years) whereas BCVA was preserved at 0.04 logMAR in sector RHO-RP patients (9.0 ± 3.0 years). Genotype-to-phenotype analysis demonstrated that p.[Pro347Leu] was associated with severe vision loss at an earlier age. Macular complications such as epiretinal membrane and cystoid macular edema were observed in 5 classical RHO-RP patients.

CONCLUSION

p.[Pro23Leu], but not p.[Pro23His], was a frequent variant causing RHO-RP in the Kyushu region of Japan. As reported in previous studies, patients with the p.[Pro347Leu] variant showed a more severe phenotype, and variants causing sector RHO-RP were associated with a good prognosis.

A 69 kb Deletion in chr19q13.42 including PRPF31 Gene in a Chinese Family Affected with Autosomal Dominant Retinitis Pigmentosa

We aimed to identify the genetic cause of autosomal dominant retinitis pigmentosa (adRP) and characterize the underlying molecular mechanisms of incomplete penetrance in a Chinese family affected with adRP. All enrolled family members underwent ophthalmic examinations. Whole-genome sequencing (WGS), multiplex ligation-dependent probe amplification (MLPA), linkage analysis and haplotype construction were performed in all participants. RNA-seq was performed to analyze the regulating mechanism of incomplete penetrance among affected patients, mutation carriers and healthy controls. In the studied family, 14 individuals carried a novel heterozygous large deletion of 69 kilobase (kb) in 19q13.42 encompassing exon 1 of the PRPF31 gene and five upstream genes: TFPT, OSCAR, NDUFA3, TARM1, and VSTM1. Three family members were sequenced and diagnosed as non-penetrant carriers (NPCs). RNA-seq showed significant differential expression of genes in deletion between mutation carriers and healthy control. The RP11 pedigree in this study was the largest pedigree compared to other reported RP11 pedigrees with large deletions. Early onset in all affected members in this pedigree was considered to be a special phenotype and was firstly reported in a RP11 family for the first time. Differential expression of PRPF31 between affected and unaffected subjects indicates a haploinsufficiency to cause the disease in the family. The other genes with significant differential expression might play a cooperative effect on the penetrance of RP11.

Long-term vitamin A supplementation in a preclinical mouse model for RhoD190N-associated retinitis pigmentosa

Retinitis pigmentosa (RP) is caused by one of many possible gene mutations. The National Institutes of Health recommends high daily doses of vitamin A palmitate for RP patients. There is a critical knowledge gap surrounding the therapeutic applicability of vitamin A to patients with the different subtypes of the disease. Here, we present a case report of a patient with RP caused by a p.D190N mutation in Rhodopsin (RHO) associated with abnormally high quantitative autofluorescence values after long-term vitamin A supplementation. We investigated the effects of vitamin A treatment strategy on RP caused by the p.D190N mutation in RHO by exposing Rhodopsin p.D190N (RhoD190N/+) and wild-type (WT) mice to experimental vitamin A-supplemented and standard control diets. The patient's case suggests that the vitamin A treatment strategy should be further studied to determine its effect on RP caused by p.D190N mutation in RHO and other mutations. Our mouse experiments revealed that RhoD190N/+ mice on the vitamin A diet exhibited higher levels of autofluorescence and lipofuscin metabolites compared to WT mice on the same diet and isogenic controls on the standard control diet. Vitamin A supplementation diminished photoreceptor function in RhoD190N/+ mice while preserving cone response in WT mice. Our findings highlight the importance of more investigations into the efficacy of clinical treatments like vitamin A for patients with certain genetic subtypes of disease and of genotyping in the precision care of inherited retinal degenerations.