Electroretinographic abnormalities associated with pregabalin: a case report

A mild form of POC1B-associated retinal dystrophy with relatively preserved cone system function

PURPOSE

Biallelic variants in POC1B are rare causes of autosomal recessive cone dystrophy associated with generalized cone system dysfunction. In this report, we describe the clinical characteristics of a Japanese male patient with POC1B-associated retinopathy with relatively preserved cone system function.

METHODS

We performed whole-exome sequencing (WES) to identify the disease-causing variants and a comprehensive ophthalmic examination, including full-field and multifocal electroretinography (ffERG and mfERG).

RESULTS

Our WES analysis identified novel compound heterozygous POC1B variants (p.Arg106Gln and p.Arg452Ter) in the patient. His unaffected mother carried the p.Arg452Ter variant heterozygously. The patient experienced decreased visual acuity in his 50s. At the age of 63, his corrected visual acuity was 20/22 in the right and 20/20 in the left eye. Fundus and fundus autofluorescence images for each eye showed no remarkable finding, except for a subtle hyperautofluorescent spot in the fovea of the left eye. Cross-sectional optical coherence tomography demonstrated blurred but a relatively preserved ellipsoid zone. The ffERG showed that amplitudes of rod and standard-flash responses were within the reference range, whereas the cone and light-adapted 30-Hz flicker amplitudes were close to, or slightly below, the reference range. The mfERG revealed substantially reduced responses with relative preservation of central function.

CONCLUSIONS

We reported the case of an older patient with POC1B-associated retinopathy, demonstrating late-onset visual decrease, good visual acuity, and relatively preserved cone system function. The disease condition was much milder than previously reported in patients with POC1B-associated retinopathy.

Electroretinographic abnormalities in Alport syndrome with a novel COL4A5 truncated variant (p.Try20GlyfsTer19)

PURPOSE

Alport syndrome comprises a heterogeneous group of inherited kidney diseases that are associated with ocular complications. In this study, we aimed to detail the clinical characteristics of a patient with X-linked Alport syndrome.

METHODS

We performed next-generation sequencing (NGS) with hybridization capture to identify the disease-causing variant of Alport syndrome and a comprehensive ophthalmic examination, including full-field electroretinography (FF-ERG).

RESULTS

Genetic testing using NGS with hybridization capture revealed a novel hemizygous variant [c.51_52delGA (p.Trp20GlyfsTer19)] in exon 1 of COL4A5. The patient underwent cataract surgery in both eyes because of decreased visual acuity and photophobia. The best-corrected visual acuity improved from 0.9 and 0.7 in the right and left eyes, respectively, to 1.5 in both eyes. Anterior-segment optical coherence tomography (OCT) revealed anterior and posterior lenticonus. Fundus photographs showed central and peripheral fleck retinopathy. Wide-field fundus autofluorescence (AF) imaging showed mottled hyper- and hypo-AF in the peripheral retina, which was consistent with peripheral fleck retinopathy. Furthermore, OCT revealed thinning of the inner retinal layers, especially at the temporal macular, but the outer retinal layers were preserved. Ganglion cell analysis showed no progression for 5 years. FF-ERG was performed at 41 (phakia) and 46 (pseudophakia) years of age. The amplitudes of dark-adapted (DA) and light-adapted (LA) responses showed selective b-wave abnormalities. The b/a-wave ratios of DA 3.0 were 1.22 and 1.16 in the right and left eyes, respectively. The amplitudes of DA 3.0 oscillatory potentials (OP) were reduced. Five years later, the amplitudes of DA and LA responses revealed no remarkable changes, except for an OP wave of DA 3.0, which was substantially reduced.

CONCLUSIONS

Our findings revealed electroretinographic abnormalities in a patient with Alport syndrome, which predominantly indicated impairment of the inner retina. Notably, little short-term progression was observed.

Can the long term using of pregabalin in fibromyalgia affect the choroid and retinal nerve fiber layer?

BACKGROUND

In this study, the effects of long-term pregabalin use on the choroid and retinal nerve fiber layer were investigated in the fibromyalgia disease.

METHODS

The patient group consisted of 41 fibromyalgia patients using pregabalin. The control group consisted of 41 newly diagnosed fibromyalgia patients who had not received any treatment yet. Choroidal and retinal nerve fiber layer thickness measurements were performed with Cirrus HD-OCT (Carl Zeiss Meditec Inc., Dublin, CA, USA) 30 minutes after pupil dilation with 1% tropicamide.

RESULTS

There was no difference in subfoveal choroidal thickness, nasal choroidal thickness and temporal choroidal thickness between the patient and control groups (p > 0.05). Increasing the duration of drug use within the patient group was found to thin the retinal nerve fiber layer (p < 0.05).

CONCLUSION

We found that pregabalin had no effect on the choroid, while it had a thinning effect for retinal nerve fiber layer. It is recommended not to be preferred pregabalin in fibromyalgia patients with retinal nerve fiber layer damage such as diabetic retinopathy and glaucoma. Patients treated with pregabalin should have regular control in the ophthalmology clinic.

Clinical characterization of autosomal dominant retinitis pigmentosa with NRL mutation in a three-generation Japanese family

PURPOSE

Retinitis pigmentosa (RP) is a heterogeneous group of inherited retinal disorders. NRL-associated autosomal dominant (AD)-RP is a rare form of AD-RP in the Japanese population. This study aimed to report a clinical characterization of NRL-associated retinopathy in a three-generation Japanese family.

CASE PRESENTATION

A total of 4 patients from a Japanese family were referred to The Jikei University School of Medicine for clinical and genetic examination. The patients included a male proband (41 years old), his daughters (5 and 6 years old), and his mother (71 years old); they underwent ophthalmic examinations, and genetic testing was performed using whole exome sequencing analysis, revealing a known variant [c.152C > T (p.Pro51Leu)] heterozygously in exon 2 of the NRL gene. Fundus photograph showed that retinal degeneration expanded to the macular and peripheral retina in an age-dependent manner. Fundus autofluorescence imaging showed hyper-autofluorescence (AF) within the macular with slightly hypo-AF in younger patients and obvious hypo-AF in older patients. Optical coherence tomography showed that the length of the ellipsoid zone tended to be longer in younger patients than in older patients. Goldmann perimetry showed an age-dependent decrease in the visual field. Furthermore, full-field electroretinographic findings revealed non-recordable rod and cone function in older patients and non-recordable rod function with preserved cone function in younger patients.

CONCLUSIONS

Our results indicated that retinal construction and function were aggravated in an age-dependent manner, and retinal degeneration, especially in the macular region, revealed milder findings than in previous cases with NRL-associated AD-RP.

The second Japanese family with Malattia Leventinese/Doyne honeycomb retinal dystrophy

PURPOSE

To describe the clinical and genetic findings of patients in the second Japanese family with Malattia Leventinese/Doyne honeycomb retinal dystrophy (ML/DHRD).

METHODS

Two patients (a 41-year-old male proband and his third son) underwent comprehensive ophthalmic examinations, including full-field and multifocal electroretinography (ERG). Sanger sequencing was performed to detect an EFEMP1 gene variant (p.Arg345Trp), which was identified as the only causative pathogenic variant.

RESULTS

Genetic analysis revealed that both patients carried the heterozygous variant, but the other unaffected family members did not. Although the proband exhibited innumerable radially distributed drusen in both the posterior poles and good visual acuity at initial presentation, bilateral choroidal neovascularization (CNV) developed during the 15-year follow-up. The proband received 15 intravitreal anti-vascular endothelial growth factor (VEGF) injections in the left eye (LE) and two injections in the right eye (RE). At 56 years of age, his decimal best-corrected visual acuity was 0.1 and 1.2 in the LE and RE, respectively. Full-field ERG showed that while the rod and combined responses were within normal amplitudes, the cone and 30-Hz flicker responses had slightly decreased amplitudes. Multifocal ERG revealed attenuated central responses in the LE and decreased temporal responses in the RE. In the 20-year-old son, multifocal ERG showed normal responses in both eyes.

CONCLUSION

This is the first report of ML/DHRD in a patient who developed bilateral CNV and received anti-VEGF treatment in both eyes. Although multifocal ERG exhibited worsening of macular function, the generalized photoreceptor function was preserved until middle age.

Homozygous single nucleotide duplication of SLC38A8 in autosomal recessive foveal hypoplasia: The first Japanese case report

PURPOSE

To characterize the clinical and genetic features of a Japanese male patient with foveal hypoplasia caused by a homozygous single nucleotide duplication in the SLC38A8 gene.

METHODS

We performed a comprehensive ophthalmic examination including full-field electroretinography (FF-ERG) and pattern-reversal visual evoked potentials (PR-VEPs). Whole-exome sequencing (WES) was performed to identify the disease-causing variant; Sanger sequencing was used for confirmation.

RESULTS

In the WES analysis, a homozygous single nucleotide duplication (c.995dupG; p.Trp333MetfsTer35) was identified in SLC38A8 of the patient. His unaffected mother carried the variant heterozygously. The patient exhibited hyperopia, congenital nystagmus, low visual acuity, and grade 4 foveal hypoplasia. Slit-lamp examination revealed mild posterior embryotoxon and goniodysgenesis. Fundus examination revealed the absence of foveal hyperpigmentation and foveal avascularity, but there were no retinal degenerative lesions. In the FF-ERG, the amplitudes of rod ERG, standard-flash, and bright-flash ERG were within the normal range; cone-mediated responses also showed nearly normal amplitudes. The PR-VEP findings revealed delayed P100 latencies and decreased amplitudes of the P100 components, but no chiasmal misrouting.

CONCLUSIONS

This report is the first report on the clinical and genetic characteristics of SLC38A8-associated foveal hypoplasia in the Japanese population. This is also the first report of normal rod- and cone-mediated responses in a patient with this disorder.

Genotype-Phenotype Correlations in RP1-Associated Retinal Dystrophies: A Multi-Center Cohort Study in JAPAN

Background: Little is known about genotype–phenotype correlations of RP1-associated retinal dystrophies in the Japanese population. We aimed to investigate the genetic spectrum of RP1 variants and provide a detailed description of the clinical findings in Japanese patients. Methods: In total, 607 patients with inherited retinal diseases were examined using whole-exome/whole-genome sequencing (WES/WGS). PCR-based screening for an Alu element insertion (c.4052_4053ins328/p.Tyr1352AlafsTer9) was performed in 18 patients with autosomal-recessive (AR)-retinitis pigmentosa (RP) or AR-cone dystrophy (COD)/cone-rod dystrophy (CORD), including seven patients with heterozygous RP1 variants identified by WES/WGS analysis, and 11 early onset AR-RP patients, in whom no pathogenic variant was identified. We clinically examined 25 patients (23 families) with pathogenic RP1 variants, including five patients (five families) with autosomal-dominant (AD)-RP, 13 patients (11 families) with AR-RP, and seven patients (seven families) with AR-COD/CORD. Results: We identified 18 pathogenic RP1 variants, including seven novel variants. Interestingly, the Alu element insertion was the most frequent variant (32.0%, 16/50 alleles). The clinical findings revealed that the age at onset and disease progression occurred significantly earlier and faster in AR-RP patients compared to AD-RP or AR-COD/CORD patients. Conclusions: Our results suggest a genotype–phenotype correlation between variant types/locations and phenotypes (AD-RP, AR-RP, and AR-COD/CORD), and the Alu element insertion was the most major variant in Japanese patients with RP1-associated retinal dystrophies.

Complete congenital stationary night blindness associated with a novel NYX variant (p.Asn216Lys) in middle-aged and older adult patients

BACKGROUND

Complete congenital stationary night blindness (CSNB) is a retinal disorder thought to be non-progressive. The purpose of this study was to characterize the clinical and genetic findings of middle-aged and older adult patients with X-linked complete CSNB.

METHODS

Three male CSNB patients (aged 62, 72, and 51 years) and one unaffected female carrier in a Japanese family were included in this study. Whole-exome sequencing (WES) was performed to determine the disease-causing variants. Co-segregation was confirmed in the family members. We performed a comprehensive ophthalmic examination on each patient.

RESULTS

In the 62-year-old patient, a novel hemizygous variant (c.648 C > A; p.Asn216Lys) of the NYX gene was identified by WES analysis. The other two patients carried the variant hemizygously, and the unaffected carrier harbored the variant heterozygously. The clinical and electroretinography (ERG) findings were very similar among all three patients. Fundus images exhibited high myopic chorioretinal atrophy with long axial length. Ultra-wide field fundus autofluorescence images showed no retinal degenerative changes except for changes resulting from high myopia and previous retinal diseases. The ERG findings showed no response in rod ERG, electronegative configuration with preserved a-waves in standard/bright-flash ERG, and preserved responses in cone and 30-Hz flicker ERG, which were compared with age-matched controls with high myopia.

CONCLUSIONS

We identified a novel missense NYX variant in a Japanese family with complete CSNB. Our clinical findings indicated that photoreceptor mediated ERG responses are well preserved even in middle-aged and older adult patients.

Transient electroretinographic abnormalities that mimic those of KCNV2 retinopathy: a case report

Purpose

The purpose of this report was to describe the case of a 68-year-old male patient with stage IV colon cancer who exhibited electroretinographic abnormalities that are similar to those of KCNV2 retinopathy.

Methods

The patient presenting with photophobia, reduced visual acuity, and poor general conditions, the onset of which occurred ten days before presentation, was examined using fundoscopy, full-field electroretinography, blood tests, and abdominal computed tomography.

Results

The patient’s decimal best-corrected visual acuity (BCVA) was 0.4 in each eye. Fundoscopy showed bull's eye-like maculopathy in both eyes. Electroretinographic findings were similar to the characteristic findings of KCNV2 retinopathy: Rod electroretinogram showed delayed and preserved b-wave amplitudes; bright-flash electroretinogram showed double troughs of a-waves; b/a ratios shown by bright-flash electroretinogram were higher than those shown by standard-flash electroretinogram; and both cone and 30-Hz flicker electroretinograms showed extinguished responses. His serum potassium level increased to 6.2 mmol/L (normal range 3.6–4.8 mmol/L) owing to hydronephrosis resulting from disseminated carcinoma. After performing an emergency surgery to treat this condition, the serum potassium level immediately decreased to a normal range. Eleven days after presentation, rod and standard/bright-flash electroretinography showed improvement in the implicit time of the rod b-waves and the a-waves. Unexpectedly, the responses recorded by cone and 30-Hz flicker electroretinography became normal. The symptoms and maculopathy disappeared, and his BCVA improved to 1.2.

Conclusions

The abnormal electroretinographic findings might be associated with the transient increase in serum potassium level.

A new PDE6A missense variant p.Arg544Gln in rod-cone dystrophy

PURPOSE

Thus far, only one Japanese patient with autosomal recessive rod-cone dystrophy (AR-RCD) associated with the phosphodiesterase 6A gene (PDE6A) has been reported. The purpose of this study was to analyze the clinical features of a Japanese female patient with AR-RCD with a novel missense variant in PDE6A.

METHODS

We performed whole-exome sequencing (WES) to identify the disease-causing variant and a comprehensive ophthalmic examination including full-field electroretinography (ERG).

RESULTS

WES analysis revealed that the patient carried a novel homozygous missense variant (c.1631G > A; p.Arg544Gln) in PDE6A. Her unaffected parents carried the heterozygous variant. The patient reported night blindness in her early 20 s. At the age of 25 years, she underwent a comprehensive ophthalmic examination. Her corrected visual acuity was 20/13 in the right and 20/10 in the left eyes. Fundus images showed degenerative changes with bone spicule pigmentation in the mid-peripheral retina, and peripheral retinal vessels were not attenuated. Ultra-wide-field fundus autofluorescence images demonstrated large hypoautofluorescent regions corresponding to the degenerative changes, surrounded by hyperautofluorescence. Cross-sectional optical coherence tomography demonstrated a preserved ellipsoid zone and retinal thickness in the center of the macula, with perifoveal atrophy. ERG responses were subnormal, revealing that rod-mediated responses were more affected than cone-mediated responses, consistent with findings observed in RCD.

CONCLUSIONS

This is the second case of a patient with AR-RCD associated with PDE6A in the Japanese population. These findings will contribute to a better clinical understanding of PDE6A-associated RCD and valuable insights for gene therapy trials.

Vitamin A deficiency after prolonged intake of an unbalanced diet in a Japanese hemodialysis patient

BACKGROUND

In industrialized countries, vitamin A deficiency (VAD) is extremely rare, except association with bariatric surgeries and hepatobiliary disorders. It is unusual that VAD develops during hemodialysis due to reduced glomerular filtration of vitamin A-binding protein. We reported the case of a 58-year-old Japanese male hemodialysis patient diagnosed with VAD.

CASE PRESENTATION

The patient undergoing hemodialysis for more than 15 years presented with progressive photophobia and night blindness and was ophthalmologically examined. He denied a history of cancer or hepatobiliary disease and reported that he loved eating prepackaged noodle bowls and foods, with prolonged low intake of fruits/vegetables. He had good visual acuity. Fundus images showed numerous white dots in the midperipheral retinae, but no degenerative changes. In baseline full-field electroretinography (ERG), b-wave responses were extremely reduced in rod ERG, a-wave amplitudes in standard-flash/strong-flash ERG were reduced to 20-25% of our controls, a- and b-wave amplitudes in cone ERG were reduced to 40-50% of the controls. Whole-exome sequencing identified no pathogenic variant for any inherited retinal disorder. He was diagnosed with VAD because of reduced serum vitamin A levels and treated with retinol palmitate. Two months after treatment commencement, the serum vitamin A level was within the normal range. Full-field ERG showed that the scotopic ERG responses markedly improved compared with baseline.

CONCLUSIONS

This is the first report of VAD associated with undernutrition in the Japanese hemodialysis population.

Novel biallelic TRPM1 variants in an elderly patient with complete congenital stationary night blindness

BACKGROUND

Little is known about whether patients with complete congenital stationary night blindness (CSNB) maintain visual function throughout their lifetime. The purpose of this report was to describe clinical and genetic features of an elderly female patient with complete CSNB that we followed for 5 years.

METHODS

Molecular genetic analysis using whole-exome sequencing (WES) was performed to detect disease-causing variants. We performed a comprehensive ophthalmic examination including full-field electroretinography (ERG).

RESULTS

In the patient, WES identified two novel variants (c.1034delT; p.Phe345SerfsTer16 and c.1880T>A; p.Met627Lys) in the TRPM1 gene. Her unaffected daughter has one of the variants. The patient reported that her visual acuity has remained unchanged since elementary school. At the age of 68 years old, fundus and fundus autofluorescence imaging showed no remarkable findings except for mild myopic changes. Goldmann perimetry showed preserved visual fields with all V-4e, I-4e, I-3e and I-2e isopters. Optical coherence tomography demonstrated preserved retinal thickness and lamination. Rod ERG showed no response; bright-flash ERG showed an electronegative configuration with minimally reduced a-waves, and cone and 30-Hz flicker ERG showed minimally reduced responses. Overall, the ERG findings of ON bipolar pathway dysfunction were consistent with complete CSNB.

CONCLUSIONS

This is the oldest reported patient with complete CSNB and biallelic TRPM1 variants. Our ophthalmic findings suggest that some patients with TRPM1-related CSNB may exhibit preserved retinal function later in life.

Novel biallelic splice-site BBS1 variants in Bardet-Biedle syndrome: a case report of the first Japanese patient

PURPOSE

To report the clinical and genetic features of a 9-year-old female Japanese patient with Bardet-Biedl syndrome (BBS).

METHODS

Genetic analysis using whole-exome sequencing (WES) was performed for the patient and her parents to identify disease-causing variants. Reverse transcriptase-polymerase chain reaction (RT-PCR) was performed to investigate the impact of splice-site variants. Comprehensive ophthalmic and systemic examinations, including electroretinography (ERG), were performed.

RESULTS

In the patient, WES identified novel compound heterozygous splice-site variants (c.124+2T>G and c.723+2T>G) in the BBS1 gene, and RT-PCR revealed skipping of exons 2 and 8 (p.N17AfsX56 and p.T198_K241del). Each parent had one of the variants. Ophthalmologically, the patient's decimal best-corrected visual acuity was 0.6 in the right eye and 0.4 in the left eye. Funduscopy revealed no apparent retinal degeneration or narrowed blood vessels in the periphery, but macular abnormalities were found on fundus autofluorescence imaging and optical coherence tomography images. Unexpectedly, non-recordable responses in rod ERG were found, with a non-recordable response of the right eye and an extremely reduced and delayed a-wave of the left eye in standard ERG, non-recordable responses in cone ERG, and extremely decreased responses in 30 Hz flicker ERG. Finally, the patient fulfilled four primary features of BBS diagnostic criteria: rod-cone dystrophy, polydactyly, central obesity, and learning disabilities, being diagnosed with BBS.

CONCLUSIONS

This is the first report of a BBS patient with biallelic splice-site BBS1 variants in the Japanese population. Disparity between funduscopic and ERG findings may be a feature of BBS1-associated rod-cone dystrophy.