Mutation spectrum of the bestrophin-1 gene in a large Chinese cohort with bestrophinopathy

Detection of Novel BEST1 Variations in Autosomal Recessive Bestrophinopathy Using Third-generation Sequencing

OBJECTIVE

Autosomal recessive bestrophinopathy (ARB), a retinal degenerative disease, is characterized by central visual loss, yellowish multifocal diffuse subretinal deposits, and a dramatic decrease in the light peak on electrooculogram. The potential pathogenic mechanism involves mutations in the BEST1 gene, which encodes Ca2+-activated Cl- channels in the retinal pigment epithelium (RPE), resulting in degeneration of RPE and photoreceptor. In this study, the complete clinical characteristics of two Chinese ARB families were summarized.

METHODS

Pacific Biosciences (PacBio) single-molecule real-time (SMRT) sequencing was performed on the probands to screen for disease-causing gene mutations, and Sanger sequencing was applied to validate variants in the patients and their family members.

RESULTS

Two novel mutations, c.202T>C (chr11:61722628, p.Y68H) and c.867+97G>A, in the BEST1 gene were identified in the two Chinese ARB families. The novel missense mutation BEST1 c.202T>C (p.Y68H) resulted in the substitution of tyrosine with histidine in the N-terminal region of transmembrane domain 2 of bestrophin-1. Another novel variant, BEST1 c.867+97G>A (chr11:61725867), located in intron 7, might be considered a regulatory variant that changes allele-specific binding affinity based on motifs of important transcriptional regulators.

CONCLUSION

Our findings represent the first use of third-generation sequencing (TGS) to identify novel BEST1 mutations in patients with ARB, indicating that TGS can be a more accurate and efficient tool for identifying mutations in specific genes. The novel variants identified further broaden the mutation spectrum of BEST1 in the Chinese population.

PdmIRD: missense variants pathogenicity prediction for inherited retinal diseases in a disease-specific manner

Accurate discrimination of pathogenic and nonpathogenic variation remains an enormous challenge in clinical genetic testing of inherited retinal diseases (IRDs) patients. Computational methods for predicting variant pathogenicity are the main solutions for this dilemma. The majority of the state-of-the-art variant pathogenicity prediction tools disregard the differences in characteristics among different genes and treat all types of mutations equally. Since missense variants are the most common type of variation in the coding region of the human genome, we developed a novel missense mutation pathogenicity prediction tool, named Prediction of Deleterious Missense Mutation for IRDs (PdmIRD) in this study. PdmIRD was tailored for IRDs-related genes and constructed with the conditional random forest model. Population frequencies and a newly available prediction tool were incorporated into PdmIRD to improve the performance of the model. The evaluation of PdmIRD demonstrated its superior performance over nonspecific tools (areas under the curves, 0.984 and 0.910) and an existing eye abnormalities-specific tool (areas under the curves, 0.975 and 0.891). We also demonstrated the submodel that used a smaller gene panel further slightly improved performance. Our study provides evidence that a disease-specific model can enhance the prediction of missense mutation pathogenicity, especially when new and important features are considered. Additionally, this study provides guidance for exploring the characteristics and functions of the mutated proteins in a greater number of Mendelian disorders.

Comprehensive Genetic Analysis Unraveled the Missing Heritability and a Founder Variant of BEST1 in a Chinese Cohort With Autosomal Recessive Bestrophinopathy

Purpose

To describe the genetic landscape of BEST1 for a large Chinese cohort with autosomal recessive bestrophinopathy (ARB), identify the missing heritability, and report a common Chinese founder variant.

Methods

We recruited 65 patients from 63 families with a clinical diagnosis of ARB. All patients underwent ophthalmic examinations and comprehensive genetic analyses, including Sanger DNA sequencing of BEST1 and whole genome sequencing (WGS). The effects of deep intronic variants (DIVs) on splicing were assessed using in vitro splicing assays in HEK293T cells and patient-derived peripheral blood mononuclear cells. Haplotype mapping was performed for 17 unrelated patients harboring variant c.867+97G>A.

Results

We identified 54 distinct disease-causing variants of BEST1 in 63 pedigrees, 62 probands with biallelic variants, and one family with monoallelic variants. Sanger DNA sequencing of BEST1 initially detected 51 variants in 61 pedigrees, including 19 probands with one heterozygous variant. Subsequent WGS, combined with supplementary Sanger sequencing, revealed three missing DIVs (c.1101-491A>G, c.867+97G>A, and c.867+97G>T) in 20 families. The novel DIV c.1101-491A>G caused an abnormal splicing resulting in a 204-nt pseudoexon (PE) insertion, whereas c.867+97G>A/T relatively strengthened an alternative donor site, resulting in a 203-nt intron retention (IR). The PE and IR generated a premature termination codon downstream. Haplotype analysis identified c.867+97G>A as a common founder variant with an allele frequency of 16%.

Conclusions

Our results expand the pathogenic variant spectrum of BEST1, and DIVs can explain almost all of the missing heritability. The c.867+97G>A DIV is a common founder variant for Chinese patients with ARB.

Autosomal recessive bestrophinopathy combined with neurofibromatosis type 1 in a patient

BACKGROUND

Neurofibromatosis type 1 (NF1) is a multisystem genetic disorder that may affect multiple systems of the body. Autosomal recessive bestrophinopathy (ARB) is a rare retinal dystrophy caused by autosomal recessively mutations in bestrophin 1 (BEST1) gene. So far, we have not retrieved any case report of the same patient with both NF1 and BEST1 gene mutations.

CASE PRESENTATION

An 8-year-old female patient with café-au-lait spots, freckling on skin presented to our ophthalmology clinic for routine ophthalmological examination. Her best corrected visual acuity (BCVA) was 20/20 in both eyes. Slit-lamp examination of both eyes revealed few yellowish-brown dome-shaped Lisch nodules over the iris surface. Fundus examination was notable for bilateral confluent yellowish subretinal deposits at macula, few yellow flecks at temporal retina, and cup-to-disc ratio of 0.2. Optical coherence tomography (OCT) revealed subretinal fluid (SRF) involving the fovea, elongated photoreceptor outer segments and mild intraretinal fluid (IRF) at bilateral macula. Fundus autofluorescence demonstrated hyperautofluorescence in the area corresponding to the subretinal deposits. Whole-exome sequencing and Sanger sequencing were used to investigate genetic mutation in the patient and her parents. A BEST1 gene heterozygous missense c.604 C > T (p.Arg202Trp) was identified in the patient and her mother. Also, the patient carries an NF1 nonsense mutation c.6637 C > T (p.Gln2213*) with the mosaic generalized phenotype. There were no visual impairments or obvious neurological, musculoskeletal, behavioral or other symptoms in this patient, so she was managed conservatively and advised to follow up regularly for a long time.

CONCLUSIONS

ARB and NF1, which are caused by two different pathogenic gene mutations, have rarely coexisted in the same patient. The discovery of pathogenic gene mutations may play a crucial role in more accurate diagnostics and genetic consultations for individuals and their families.

Novel MFSD8 mutation causing non-syndromic asymmetric adult-onset macular dystrophy

BACKGROUND

MFSD8 mutations can cause type 7 neuronal ceroid lipofuscinosis, a systemic disorder that includes vision loss; however, such mutations can also cause isolated retinal dystrophy with vision loss without systemic signs or symptoms as first identified in 2015. This report details a previously unreported combination of compound heterozygous variants in the MFSD8 gene causing a non-syndromic, bilateral central macular dystrophy presenting in adulthood.

MATERIALS AND METHODS

We present a case of MFSD8-associated retinal dystrophy with multimodal imaging and a review of relevant literature.

RESULTS

A 57-year-old female presented for subacute, unilateral blurriness in her right eye. Best corrected visual acuity was 20/250 and 20/50 in the right and left eyes, respectively. Fundus examination and multimodal imaging revealed blunted foveal reflexes and optical gap with subfoveal ellipsoid zone loss in both eyes, right greater than left. Full field electroretinography results were within normal limits while the Arden ratio on electro-oculography was abnormal in both eyes, right more so than left. Genetic testing revealed apparently causative compound heterozygous mutations in the MFSD8 gene: c.154G>A, p.(Gly52Arg) and c.1006G>C, p.(Gluc336Gln). Visual acuity over one year of follow-up has remained stable.

CONCLUSIONS

To authors' knowledge, this report is first description of this combination of mutations in the MFSD8 gene leading to non-syndromic adult-onset macular dystrophy.

Genetic and clinical features of BEST1-associated retinopathy based on 59 Chinese families and database comparisons

Variants in BEST1 are one of the most common cause of retinopathy mainly involving the retinal pigment epithelium with both dominant and recessive traits. This study aimed to describe the characteristics of potential pathogenic variants (PPVs) in BEST1 and their associated clinical features. Variants in BEST1 were collected from our in-house exome sequencing data and systematically evaluated by in silico prediction tools as well as genotype-phenotype analysis. The pathogenicity features of the BEST1 variants were further assessed through database comparison among the in-house data, Genome Aggregation Database from the general population, and all previously published literature. The clinical information of the in-house patients was summarized. The PPVs in BEST1 were identified in 66 patients from 59 families, including 32 families with Best vitelliform macular dystrophy (BVMD) and 27 families with autosomal recessive bestrophinopathy (ARB). These PPVs included 31 missense variants, seven truncation variants, one in-frame deletion, and a known 3-untranslated region variant. All the truncations detected in our study were exclusively involved in ARB but not BVMD. Among the 31 missense variants, 18 missenses associated with BVMD in the dominant trait were clustered in four hotspot regions with statistically significant differences from the recessive missenses. Except for distinct macular changes, there were no statistically significant differences among the other associated clinical features between BVMD and ARB, including peripheral retinopathy, high hyperopia, and angle-closure glaucoma. In conclusion, BEST1-associated dominant retinopathy was preferentially caused by missense variants located in important functional regions. Truncations were most likely benign in heterozygous status. Future studies are expected to elucidate the mystery of the same missense variants contributing to both BVMD and ARB.

Impaired Bestrophin Channel Activity in an iPSC-RPE Model of Best Vitelliform Macular Dystrophy (BVMD) from an Early Onset Patient Carrying the P77S Dominant Mutation

Best Vitelliform Macular dystrophy (BVMD) is the most prevalent of the distinctive retinal dystrophies caused by mutations in the BEST1 gene. This gene, which encodes for a homopentameric calcium-activated ion channel, is crucial for the homeostasis and function of the retinal pigment epithelia (RPE), the cell type responsible for recycling the visual pigments generated by photoreceptor cells. In BVMD patients, mutations in this gene induce functional problems in the RPE cell layer with an accumulation of lipofucsin that evolves into cell death and loss of sight. In this work, we employ iPSC-RPE cells derived from a patient with the p.Pro77Ser dominant mutation to determine the correlation between this variant and the ocular phenotype. To this purpose, gene and protein expression and localization are evaluated in iPSC-RPE cells along with functional assays like phagocytosis and anion channel activity. Our cell model shows no differences in gene expression, protein expression/localization, or phagocytosis capacity, but presents an increased chloride entrance, indicating that the p.Pro77Ser variant might be a gain-of-function mutation. We hypothesize that this variant disturbs the neck region of the BEST1 channel, affecting channel function but maintaining cell homeostasis in the short term. This data shed new light on the different phenotypes of dominant mutations in BEST1, and emphasize the importance of understanding its molecular mechanisms. Furthermore, the data widen the knowledge of this pathology and open the door for a better diagnosis and prognosis of the disease.

Branch retina vein occlusion combined with angle-closure glaucoma is associated with a mutation in BEST1: a case report

BACKGROUND

It is rare for a patient to be diagnosed with branch retina vein occlusion (BRVO), angle-closure glaucoma (ACG) and autosomal recessive bestrophinopathy (ARB). ARB is strongly associated with ACG. Although glaucoma is a significant risk factor for RVO, there is a plausible relationship between ACG and BRVO. To discuss correlation of these diseases is necessary.

CASE PRESENTATION

The genetic testing and medical treatment of a patient with ocular fundus diseases and ACG were recorded. We present a 47-year-old male patient with BRVO who was diagnosed with angle-closure glaucoma and a homozygous mutation of c.140G > A (p.R47H) in BEST1. Intravitreal ranibizumab was administered in combination with three antiglaucomatous eyedrops to lower intraocular pressure (IOP) in the right eye. One month later, BCVA improved to 0.3. IOP was controlled at 13 mmHg.

CONCLUSIONS

ACG was likely combined to ARB, while there's a plausible relationship between ACG and BRVO.

Disease expression caused by different variants in the BEST1 gene: genotype and phenotype findings in bestrophinopathies

Purpose:

To analyse the spectrum of clinical features and molecular genetic data in a series of patients carrying likely disease-associated variants in the BEST1 gene.

Methods:

Retrospective observational analysis of clinical data extracted from the medical records of visual function, multimodal imaging and electrophysiology of 62 eyes of 31 patients. Molecular genetic analysis was performed by means of panel-based NGS or Sanger sequencing.

Results:

The spectrum of variants in the BEST1 gene comprised 19 different variants and three of which are novel. Fundus photographs and OCT images allowed categorization of 52 eyes as Best vitelliform macular dystrophy (BVMD) with stages 1 to 5 and 10 eyes with autosomal recessive bestrophinopathy (ARB), with more severe phenotype. One patient was shown to be heterozygous for a variant, which has so far been described only in ARB, but this patient had the BVMD phenotype. There was no significant progression of the visual acuity during the follow-up period of 5 years both in BVMD and ARB. The most prevalent pattern of fundus autofluorescence (FAF) in BVMD was ‘patchy’. There were diverse visual field defects in static automated perimetry (SAP) depending on the stage. The Arden ratio was significantly lower in ARB patients and in eyes with stage 5 of BVMD.

Conclusions:

The genotype does not always predict the phenotype in patients with BVMD and ARB; however, having two mutations in the BEST1 gene causes a more severephenotype. FAFhelped to distinguish ARB from BVMD. Most of the observed eyesdidnotprogressfunctionallyduringthefollow-up.ARBandtheatrophicstageof BVMD as the disease end-stage had the worst visual functions and EOG results.

Mutation Analysis of the RPGR Gene in a Chinese Cohort

Purpose: The purpose of this study was to investigate the clinical and genetic characteristics of the retinitis pigmentosa GTPase regulatory factor gene (RPGR) in a Chinese cohort.

Methods: A retrospective analysis was performed on 80 subjects with RPGR-retinal dystrophy (RPGR-RD) for detailed genetic and clinical characterization. The panel-based next-generation sequencing of 792 causative genes involved in common genetic eye diseases was conducted in all individuals, followed by clinical variant interpretation. Information, including age, sex, geographic distribution, family history, consanguineous marriage, age at symptom onset, disease duration, best corrected visual acuity (BCVA), and complete ophthalmologic examination results, was collected.

Results: This cohort (41 men and 39 women) included 26 families (26 probands and their available family members) and 13 sporadic cases. The average age of these participants was 36.35 ± 17.68 years, and the majority of the families were from eastern China (28 families, 71.79%). The average duration of disease in the probands was 22.68 ± 15.80 years. In addition, the average BCVA values of the right and left eyes in the probands were 0.96 ± 0.77 and 1.00 ± 0.77, respectively. A total of 34 RPGR variants were identified, including 6 reported variants and 28 novel variants. Among these variants, NM_001034853.1: c.2899_2902delGAAG and c.2744_2745ins24 were considered de novo variants. The majority of the RPGR variants were classified as likely pathogenic, accounting for 70.59% of the variants (24 variants). The most common nucleotide and amino acid changes identified in this study were deletions (16 variants, 45.06%) and frameshifts (17 variants, 50.00%), respectively. Genetic analysis revealed that these RPGR variants were distributed in 10 different subregions of RPGR, and 70.59% of the RPGR variants (24 variants) were located in exon 15. Four RPGR variants, NM_001034853.1: c.2405_2406delAG, c.1345C > T, c.2218G > T and c.2236_2237delGA, occurred at a very high frequency of 28.21% (11 families) among 39 unrelated families.

Conclusion: This study expands the known mutational spectrum of RPGR, and we provide a new reference for the genetic diagnosis of RPGR variants.

Genotypic spectrum and phenotype correlations of EYS-associated disease in a Chinese cohort

Background

To date, certain efforts have been made to investigate the clinical and genetic characteristics of patients with EYS mutations. However, data for Chinese patients are limited.

Objectives

To perform a detailed phenotyping and genetic characterization of 55 Chinese patients with EYS-RD, and to identify risk factors for these clinical data.

Methods

A total of 55 patients with EYS-RD were recruited. Best-corrected visual acuity (BCVA), patient age, age at symptom onset, disease duration, and genetic information were collected.

Results

Thirty-six novel variants, three hot mutations of EYS (30.3%, c.6416G>A, c.6557G>A, c.7492G>C) and one hot region (49.06%, Laminin G domains) were identified. In all, 36.84% of the mutations occurred at base G site, and majority of mutations (56.56%) were missense. Late-truncating mutations are significantly more prevalent (41.30%). The mean age of onset was 15.65 ± 14.67 years old; it had no significant correlation with genotype. The average BCVA was 0.73 ± 0.93 LogMAR, and 61.8% of eyes had a BCVA better than 0.52 logMAR. BCVA was positively correlated with disease duration time. The mean MD was 23.18 ± 7.34 dB, MD showed a significant correlation with genotype and age. Cataract was present in 56.45% of patients, and 42.59% of patients showed an absence of pigmentation in the retina. Cataract and hyperpigmentation both showed a significant correlation with age.

Conclusions

EYS-RD is associated with a moderate phenotype with onset around adolescence, but great variability. Our study largely enhances the current knowledge of phenotypic and genotypic characteristics of EYS-RD, which could pave the way for better management of these patients.

Comprehensive analysis of genetic and clinical characteristics of 30 patients with X-linked juvenile retinoschisis in China

Purpose

To provides the clinical and genetic characteristics of a series of Chinese patients with X‐linked juvenile retinoschisis (XLRS) through multimodal imaging and next‐generation sequencing.

Methods

Thirty patients (60 eyes) from 29 unrelated families of Chinese origin with XLRS were screened using multigene panel testing, and underwent a complete clinical evaluation. All variants identified in this study and reported in the Human Gene Mutation Database were analysed.

Results

Twenty‐five distinct variants in the retinoschisin gene were identified, of which eight were novel, and one was de novo. Missense mutations were the most prevalent type, and mutation hot spot was localized in the discoidin domain. The mean Snellen best‐corrected visual acuity was 0.28 ± 0.17. Of all eyes presenting with schisis, 92.86% had lamellar schisis and 62.5% had peripheral schisis. Schisis changes mostly involved inner and outer nuclear layers. X‐linked juvenile retinoschisis (XLRS) patients had a high incidence of complications, and peripheral schisis was a risk factor for it. No obvious genotype–phenotype association was observed.

Conclusion

This study provides comprehensive analyses of the genetic and clinical characteristics of XLRS in a cohort of Chinese patients. The fourth de novo mutation in RS1 was identified. And we show that XLRS has a wide spectrum of clinical characteristics; hence, molecular diagnosis is crucial for its diagnosis, differential diagnosis and genetic counselling. Peripheral schisis is a risk factor for the high incidence of complications, and no clear genotype–phenotype correlations were found.

Whole-exome sequencing in 168 Korean patients with inherited retinal degeneration

Background

To date, no genetic analysis of inherited retinal disease (IRD) using whole-exome sequencing (WES) has been conducted in a large-scale Korean cohort. The aim of this study was to characterise the genetic profile of IRD patients in Korea using WES.

Methods

We performed comprehensive molecular testing in 168 unrelated Korean IRD patients using WES. The potential pathogenicity of candidate variants was assessed using the American College of Medical Genetics and Genomics and the Association for Molecular Pathology variant interpretation guidelines, in silico prediction tools, published literature, and compatibility with known phenotypes or inheritance patterns.

Results

Causative variants were detected in 86/168 (51.2%) IRD patients, including 58/107 (54.2%) with retinitis pigmentosa, 7/15 (46.7%) with cone and cone-rod dystrophy, 2/3 (66.6%) with Usher syndrome, 1/2 (50.0%) with congenital stationary night blindness, 2/2 (100.0%) with Leber congenital amaurosis, 1/1 (100.0%) with Bietti crystalline dystrophy, 1/1 (100.0%) with Joubert syndrome, 9/10 (90.0%) with Stargardt macular dystrophy, 1/10 (10.0%) with vitelliform macular dystrophy, 1/11 (9.1%) with other forms of macular dystrophy, and 3/4 (75.0%) with choroideraemia. USH2A, ABCA4, and EYS were the most common causative genes associated with IRD. For retinitis pigmentosa, variants of USH2A and EYS were the most common causative gene mutations.

Conclusions

This study demonstrated the distribution of causative genetic mutations in Korean IRD patients. The data will serve as a reference for future genetic screening and development of treatment modalities for Korean IRD patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12920-021-00874-6.

A novel phenotype in a family with autosomal dominant retinal dystrophy due to c.1430A > G in retinoid isomerohydrolase (RPE65) and c.37C > T in bestrophin 1 (BEST1)

PURPOSE

The c.1430A > G (Asp477Gly) variant in RPE65 has been reported in Irish and Scottish families with either an autosomal dominant retinal dystrophy (adRD) that resembles choroideremia, a vitelliform macular dystrophy or an isolated macular atrophy. We report novel features on multimodal imaging and the natural history of a family harbouring this variant in combination with the BEST1 c.37C > T (Arg13Cys) variant.

METHODS

Members of a family with an adRD were examined clinically to ascertain phenotype and underwent genetic testing. Multimodal imaging included widefield colour fundus photography, quantitative autofluorescence (qAF) and spectral domain optical coherence tomography. Electrophysiology and microperimetry were also performed.

RESULTS

Vision loss was attributed to foveal atrophy in the proband and choroidal neovascularisation and a vitello-eruptive lesion in one affected son. Peripheral retinal white dots corresponding to subretinal deposits were seen in three patients. The median qAF₈ values in the proband (I:1) were low (40 and 101 in OD and OS) at age 79. Similarly, the qAF₈ values for the middle son (II:2) were also low (100 and 87 in ODS and OS) at age 60. Electrophysiology showed disproportionate reduction in Arden ratio prior to the gradual loss of full-field responses. Microperimetry demonstrated an enlarging scotoma in the proband.

CONCLUSIONS

The coexistence of the pathogenic BEST1 c.37C > T variant may modify clinical features observed in RPE65 adRD. This study expands our understanding of RPE65 adRD as a retinoid cycle disorder supported by the reduced qAF, fine white retinal dots and corresponding subretinal deposits on OCT in affected members.

Clinical Heterogeneity in Autosomal Recessive Bestrophinopathy with Biallelic Mutations in the BEST1 Gene

Autosomal recessive bestrophinopathy (ARB) has been reported as clinically heterogeneous. Eighteen patients (mean age: 22.5 years; 15 unrelated families) underwent ophthalmological examination, fundus photography, fundus autofluorescence, and optical coherence tomography (OCT). Molecular genetic testing of the BEST1 gene was conducted by the chain-terminating dideoxynucleotide Sanger methodology. Onset of symptoms (3 to 50 years of age) and best-corrected visual acuity (0.02–1.0) were highly variable. Ophthalmoscopic and retinal imaging defined five phenotypes. Phenotype I presented with single or confluent yellow lesions at the posterior pole and midperiphery, serous retinal detachment, and intraretinal cystoid spaces. In phenotype II fleck-like lesions were smaller and extended to the far periphery. Phenotype III showed a widespread continuous lesion with sharp peripheral demarcation. Single (phenotype IV) or multifocal (phenotype V) vitelliform macular dystrophy-like lesions were observed as well. Phenotypes varied within families and in two eyes of one patient. In addition, OCT detected hyperreflective foci (13/36 eyes) and choroidal excavation (11/36). Biallelic mutations were identified in each patient, six of which have not been reported so far [c.454C>T/p.(Pro152Ser), c.620T>A/p.(Leu207His), c.287_298del/p.(Gln96_Asn99del), c.199_200del/p.(Leu67Valfs*164), c.524del/p.(Ser175Thrfs*19), c.590_615del/p.(Leu197Profs*26)]. BEST1-associated ARB presents with a variable age of onset and clinical findings, that can be categorized in 5 clinical phenotypes. Hyperreflective foci and choroidal excavation frequently develop as secondary manifestations.

The Clinical Features and Genetic Spectrum of a Large Cohort of Chinese Patients With Vitelliform Macular Dystrophies

PURPOSE

To provide the clinical and genetic characteristics of a large cohort of Chinese patients with vitelliform macular dystrophies.

DESIGN

Cross-sectional study.

METHODS

One hundred and thirty-four unrelated Chinese patients diagnosed with Best vitelliform macular dystrophy (BVMD), autosomal recessive bestrophinopathy (ARB), or adult vitelliform macular dystrophy (AVMD) were enrolled. Detailed ophthalmic examinations and genetic testing on vitelliform macular dystrophy-related genes were performed. Genotype and phenotype association were analyzed among different diagnostic groups.

RESULTS

In total, 87 BVMD, 30 AVMD, and 17 ARB patients were enrolled in this study. Genetic analysis identified 37 BEST1 mutations in 53 patients with BVMD and ARB. Of these, 5 variants (c.254A>C, c.291C>G, c.722C>G, c.848_850del, c.1740-2A>C) were novel. The variant c.898G>A was a hotspot mutation, which was identified in 13 patients with BVMD and 1 patient with ARB. There were significant differences of ocular biometric parameters among patients with homozygous or compound heterozygous mutations, heterozygous mutations, and those without mutations of BEST1. Homozygous or compound heterozygous patients had shortest axial length (AL), shallowest anterior chamber depth (ACD), and highest intraocular pressure (IOP); patients without mutations had longest AL, deepest ACD, and lowest IOP; and heterozygous patients were in between. Moreover, 7 patients harboring heterozygous mutations in BEST1 and 3 patients without BEST1 mutations showed similar clinical appearance to ARB in our cohort.

CONCLUSIONS

This is the largest sample size study of Chinese vitelliform macular dystrophy patients. Our results indicated that assessment of angle-closure risk is a necessary consideration for all types of BEST1-related vitelliform macular dystrophies. The study expanded both the clinical and genetic findings of 3 common types of vitelliform macular dystrophies in a Chinese population.

Genetic and clinical findings of panel-based targeted exome sequencing in a northeast Chinese cohort with retinitis pigmentosa

Background

Panel‐based targeted exome sequencing was used to analyze the genetic and clinical findings of targeted genes in a cohort of northeast Chinese with retinitis pigmentosa.

Methods

A total of 87 subjects, comprising 23 probands and their family members (total patients: 32) with confirmed retinitis pigmentosa were recruited in the study. Panel‐based targeted exome sequencing was used to sequence the patients and family members, all subjects with retinitis pigmentosa underwent a complete ophthalmologic examination.

Results

Of the 23 probands, the clinical manifestations include night blindness, narrowing of vision, secondary cataracts, choroidal atrophy, color blindness, and high myopia, the average age of onset of night blindness is 12.9 ± 14 (range, 0–65; median, 8). Posterior subcapsular opacities is the most common forms of secondary cataracts (nine cases, 39.1%), and peripheral choroidal atrophy is the most common form of secondary choroidal atrophy (12 cases, 52.2%). Of these probands with complication peripheral choroidal atrophy, there were eight probands (66.7%, 8/12) caused by the pathogenic variation in USH2A gene. A total of 17 genes and 45 variants were detected in 23 probands. Among these genes, the commonest genes were USH2A (40%; 18/45), RP1 (15.6%; 7/45), and EYS (8.9%; 4/45), and the top three genes account for 56.5% (13/23) of diagnostic probands. Among these variants, comprising 22 (48.9%) pathogenic variants, 14 (31%) likely pathogenic variants, and nine (20%) uncertain clinical significance variants, and 22 variants was discovered first time. Most of the mutations associated with RP were missense (53.3%, 24/45), and the remaining mutation types include frameshift (35.6%, 16/45), nonsense (6.7%, 3/45), and spliceSite (4.4%, 2/45). Among the probands with mutations detected, compound heterozygous forms was detected in 13 (56.5%, 13/23) probands, and digenic inheritance (DI) forms was detected in five (21.7%, 5/23) probands.

Conclusion

Panel‐based targeted exome sequencing revealed 23 novel mutations, recognized different combinations forms of variants, and extended the mutational spectrum of retinitis pigmentosa and depicted common variants in northeast China.

Genetic and clinical analysis in Chinese patients with retinitis pigmentosa caused by EYS mutations

Background

Panel‐based targeted exome sequencing was applied to identify the pathogenic variants and genetic characteristics of retinitis pigmentosa (RP) in two Chinese families, and to gain a deeper understanding of the relationship between clinical manifestations and genotypes.

Methods

A total of 17 subjects, comprising two probands (total patients: four subjects) and their family member, were recruited in this study. All subjects underwent comprehensive ophthalmic examinations and clinical evaluations, and the complete history and medical records were collected according to the standard procedures. All participants were screened using the multigene panel test (Target_Eye_792_V2 chip), and Sanger sequencing was used to confirm the candidate variants.

Results

Among these two families, a total of three novel mutations in the EYS gene were identified in patients, including a homozygous frameshift mutation c.9252_9253insT detected in two patients in one family, and the compound heterozygous splicesite mutation c.5644+2T>C and frameshift mutation c.1920_1923delTGAG detected in two patients in the another family. All patients in both families had early onset of night blindness and poor visual acuity, and with typical posterior capsule opacification. The mutation co‐segregated within all recruited individuals. In addition, one patient with compound heterozygous mutations was found to have typical blue‐blindness symptoms and detected a previously reported disease‐causing mutation c.235G>A in OPN1SW gene, which caused blue blindness manifestations and was first discovered in patient combined with RP causative genes.

Conclusions

Panel‐based targeted exome sequencing was used to identify three novel variants of RP causative gene, and we also detected a known pathogenic variants of blue‐blindness causative genes in two patients. Our finding will provide a powerful basis for genetic counseling and enhance our current understanding of the genetics factors for RP families.

Clinical and Genetic Findings of Autosomal Recessive Bestrophinopathy (ARB)

Mutations in BEST1 cause several phenotypes including autosomal dominant (AD) Best vitelliform macular dystrophy type 2 (BVMD), AD vitreo-retino-choroidopathy (ADVIRC), and retinitis pigmentosa-50 (RP50). A rare subtype of Bestrophinopathy exists with biallelic mutations in BEST1. Its frequency is estimated to be 1/1,000,000 individuals. Here we report 6 families and searched for a genotype-phenotype correlation. All patients were referred due to reduced best-corrected visual acuity (BCVA), ranging from 0.1/10 to 3/10. They all showed vitelliform lesions located at the macula, sometimes extending into the midperiphery, along the vessels and the optic disc. Onset of the disease varied from the age of 3 to 25 years. Electrooculogram (EOG) revealed reduction in the EOG light rise in all patients. Molecular analysis revealed previously reported mutations p.(E35K);(E35K), p.(L31M);(L31M), p.(R141H);(A195V), p.(R202W);(R202W), and p.(Q220*);(Q220*) in five families. One family showed a novel mutation: p.(E167G);(E167G). All mutations were heterozygous in the parents. In one family, heterozygous children showed various reductions in the EOG light rise and autofluorescent deposits. Autosomal recessive Bestrophinopathy (ARB), although rare, can be recognized by its phenotype and should be validated by molecular analysis. Genotype-phenotype correlations are difficult to establish and will require the analysis of additional cases.