Datasets-Based IMPDH1 Revisited: Heterozygous Missense Variants for Dominant Retinitis Pigmentosa While Truncation Variants Are Likely Non-Pathogenic.

PURPOSE: Heterozygous variants of IMPDH1 are associated with autosomal dominant retinitis pigmentosa (adRP). The current study aims to investigate the characteristics of the adRP-associated variants. METHODS: IMPDH1 variants from our exome sequencing dataset were retrieved and systemically evaluated through multiple online prediction tools, comparative genomics (in-house dataset, HGMD, and gnomAD), and phenotypic association. Potential pathogenic variants (PPVs) were further confirmed by Sanger sequencing and segregation analysis. RESULTS: In total, seven heterozygous PPVs (six missenses and one inframe) were identified in 10 families with RP, in which six of the seven might be classified as pathogenic or likely pathogenic while one others as variants of uncertain significance. IMPDH1 variants contributed to 0.7% (10/1519) of RP families in our cohort, ranking the top four genes implicated in adRP. These adRP-associated variants were located in exons 8-10, a region within or downstream of the CBS domain. All these variants were predicted to be damaged by at least three of the six online prediction tools. Two truncation variants were considered non-pathogenic. Hitherto, 41 heterozygous variants of IMPDH1 were detected in 110 families in published literature, including 33 missenses, two inframes, and six truncations (including a synonymous variant affecting splicing). Of the 35 missense and inframe variants, most were clustered in exons 8-10 (77.1%, 27/35), including 18 (51.4%, 18/35) in exon 10 accounting for 70.9% (78/110) of the families. However, truncation variants were enriched in the general population with a pLI value of 0 (tolerated), and the reported variants in patients with RP did not cluster in specific region. CONCLUSIONS: Our data together with comprehensive analysis of existing datasets suggest that causative variants of IMPDH1 are usually missense and mostly clustered in exons 8-10. Conversely, most missense variants outside this region and truncation variants should be interpreted with great care in clinical gene test.

Variant and clinical landscape of Leber hereditary optic neuropathy based on 1516 families with mtDNA variants in a tertiary centre.

AIMS: To investigate the clinical characteristics of Leber hereditary optic neuropathy (LHON) with mtDNA primary mutations to better understand features associated with prognosis. METHODS: This study enrolled 1540 LHON patients from 1516 unrelated families genetically confirmed by Sanger or whole-mitochondrial sequencing between 1997 and 2022. The spectrum of variants was summarised and compared in different ethnic groups. Clinical data from outpatients were collected, including onset age, disease course, optic disc categories and the corresponding visual acuity. RESULTS: Of the 1516 LHON families, 13 pathogenic mtDNA variants were detected, in which the proportion of m.11778G>A, m.3460G>A and m.3635G>A was significantly different from non-East Asians (p<0.0001). About 95% (1075/1131) of patients were between 8 and 40 years old at onset, with a median onset age of 16. The eyes of m.14484T>C patients presented with better visual acuity and slower progression across patients with different onset ages and initial severity. Eyes (N=439) with available fundus images were divided into four categories (C1-C4). The progression grades were derived from the category and the corresponding time course, where a higher grade (C3-C4 within 1 year) was associated with greater visual impairment than a lower grade (C1-C2 over 1 year) (p=4.60E-05) . A prognostic matrix showed that later onset and a higher progression grade are associated with higher risk of blindness. CONCLUSION: Compared with non-East Asians, Chinese LHON patients had higher proportions of m.11778G>A and m.3635G>A and lower m.3460G>A mutations. A novel progression grade derived from optic disc category was proposed. The prognostic matrix indicated that lower grade and younger-onset age are the most favourable prognostic factors.

Clinical and genetic risk factors underlying severe consequence identified in 75 families with unilateral high myopia.

BACKGROUNDS: Unilateral high myopia (uHM), commonly observed in patients with retinal diseases or only with high myopia, is frequently associated with amblyopia with poor prognosis. This study aims to reveal the clinical and genetic spectrum of uHM in a large Chinese cohort. METHODS: A total of 75 probands with simplex uHM were included in our Pediatric and Genetic Eye Clinic. Patients with significant posterior anomalies other than myopic fundus changes were excluded. Variants were detected by exome sequencing and then analyzed through multiple-step bioinformatic and co-segregation analysis and finally confirmed by Sanger sequencing. Genetic findings were correlated with associated clinical data for analysis. RESULTS: Among the 75 probands with a mean age of 6.21 ± 4.70 years at the presentation, myopic fundus of C1 and C2 was observed in 73 (97.3%) probands. Surprisingly, specific peripheral changes were identified in 63 eyes involving 36 (48.0%) probands after extensive examination, including peripheral retinal avascular zone (74.6%, 47/63 eyes), neovascularization (54.0%), fluorescein leakage (31.7%), peripheral pigmentary changes (31.7%), and others. Exome sequencing identified 21 potential pathogenic variants of 13 genes in 20 of 75 (26.7%) probands, including genes for Stickler syndrome (COL11A1 and COL2A1; 6/20), FEVR (FZD4, LRP5, and TSPAN12; 5/20), and others (FBN1, GPR179, ZEB2, PAX6, GPR143, OPN1LW, FRMD7, and CACNA1F; 9/20). For the peripheral retinal changes in the 20 probands, variants in Stickler syndrome-related genes were predominantly associated with retinal pigmentary changes, lattice degeneration, and retinal avascular region, while variants in genes related to FEVR were mainly associated with the avascular zone, neovascularization, and fluorescein leakage. CONCLUSIONS: Genetic defects were identified in about one-fourth of simplex uHM patients in which significant consequences may be hidden under a classic myopic fundus in up to half. To our knowledge, this is the first systematic genetic study on simplex uHM to date. In addition to routine care of strabismus and amblyopia, careful examination of the peripheral retina and genetic screening is warranted for patients with uHM in order to identify signs of risk for retinal detachment and other complications and provide meaningful genetic counseling.

Clinical and Genetic Landscape of Ectopia Lentis Based on a Cohort of Patients From 156 Families.

Purpose: To extend the mutation spectrum and explore the characteristics of genotypes and ocular phenotypes in ectopia lentis (EL). Methods: Variants in all 14 reported EL-associated genes were selected from in-house data sets as well as literature review, and available clinical data were analyzed. Results: Likely pathogenic variants in three genes were identified in 156 unrelated families with EL from the in-house cohort, of which 97.4% resulted from variants in FBN1, whereas the remaining were caused by variants in ADAMTSL4 (1.3%) and LTBP2 (1.3%). A comparative analysis of the in-house data and literature review suggested several characteristics: (1) a higher proportion of cysteine involvement variants in FBN1, either variants introducing or eliminating cysteine, and an earlier diagnosis age were presented in our cohort than in published literature; (2) the axial length (AL) and refractive error increased more rapidly with age in preschool EL children than normal children, and the increased rate of AL was slower in patients with surgery than those without surgery; (3) aberrant astigmatism was common in EL; and (4) worse vision and earlier onset age were observed in patients with non-FBN1 variants (all P < 0.05). Conclusions: Variants in FBN1 are the predominant cause of EL, with the most common cysteine involvement variants. Early-stage EL manifests refractive error but gradually converts to axial myopia through defocus introduced by lens dislocation. Aberrant astigmatism is a suggestive sign of EL. Non-FBN1 variants cause early-onset and severe phenotypes. These results provide evidence for early diagnosis as well as timely treatment for EL.

Defect of TIMP4 Is Associated with High Myopia and Participates in Rat Ocular Development in a Dose-Dependent Manner.

Thinning of the sclera happens in myopia eyes owing to extracellular matrix (ECM) remodeling, but the initiators of the ECM remodeling in myopia are mainly unknown. The matrix metalloproteinase (MMPs) and tissue inhibitors of matrix metalloproteinase (TIMPs) regulate the homeostasis of the ECM. However, genetic studies of the MMPs and TIMPs in the occurrence of myopia are poor and limited. This study systematically investigated the association between twenty-nine genes of the TIMPs and MMPs families and early-onset high myopia (eoHM) based on whole exome sequencing data. Two TIMP4 heterozygous loss-of-function (LoF) variants, c.528C>A in six patients and c.234_235insAA in one patient, were statistically enriched in 928 eoHM probands compared to that in 5469 non-high myopia control (p = 3.7 × 10-5) and that in the general population (p = 2.78 × 10-9). Consequently, the Timp4 gene editing rat was further evaluated to explore the possible role of Timp4 on ocular and myopia development. A series of ocular morphology abnormalities in a dose-dependent manner (Timp4-/- < Timp4+/- < Timp4+/+) were observed in a rat model, including the decline in the retinal thickness, the elongation in the axial length, more vulnerable to the form deprivation model, morphology changes in sclera collagen bundles, and the decrease in collagen contents of the sclera and retina. Electroretinogram revealed that the b-wave amplitudes of Timp4 defect rats were significantly reduced, consistent with the shorter length of the bipolar axons detected by HE and IF staining. Heterozygous LoF variants in the TIMP4 are associated with early onset high myopia, and the Timp4 defect disturbs ocular development by influencing the morphology and function of the ocular tissue.

Double Hyperautofluorescence Rings as a Sign of CFAP410-related Retinopathy.

Purpose: Variants in CFAP410 have been reported to cause retinal dystrophy with or without systemic symptoms. This study was designed to characterize the fundus changes of patients with biallelic variants in CFAP410. Methods: Variants in CFAP410 were identified through whole exome sequencing and targeted exome sequencing of 10,530 probands. Biallelic variants in CFAP410 were evaluated by comprehensive in silico analysis and confirmed by Sanger sequencing and segregation analysis. Ocular phenotypes including fundus photographs, scanning laser ophthalmoscopy, autofluorescence images, ERG, and optical coherence tomography were characterized. Results: Nine patients from eight families were homozygotes or compound heterozygotes for a total of four variants in CFAP410, including c.144-6_159del (novel), c.340_351dup, c.347C>T, and c.545+1G>A. Three patients were diagnosed with cone-rod dystrophy, and the remaining six patients with RP. Among eight patients performed with ultra-wide scanning laser ophthalmoscopy, double hyperautofluorescence rings inside and outside of the macular vascular arcades were observed in six patients, and the remaining two older patients demonstrated single hyperautofluorescence ring surrounded by pigmentation. CFAP410-associated retinopathy in early stage was generally tapetoretinal degeneration without noticeable bone spicule pigmentation, with more severe degeneration in the inferior nasal retina. ERG recordings delineated a severely reduced cone response and mildly to severely reduced rod response. Posterior staphyloma was seen in seven patients who underwent optical coherence tomography examinations. Conclusions: The present study demonstrates the fundus characteristics of patients with biallelic variants in CFAP410 and expands the genotype-phenotype spectrum of CFAP410-related retinal degeneration, in which posterior staphyloma together with double hyperautofluorescence rings might be common peculiar signs.

Retinopathy as an initial sign of hereditary immunological diseases: report of six families and challenges in eye clinic.

Introduction: Retinal degenerative or inflammatory changes may occur with hereditary immunological disorders (HID) due to variants in approximately 20 genes. This study aimed to investigate if such retinopathy may present as an initial sign of immunological disorders in eye clinic. Methods: The variants in the 20 genes were selected from in-house exome sequencing data from 10,530 individuals with different eye conditions. Potential pathogenic variants were assessed by multistep bioinformatic analysis. Pathogenic variants were defined according to the ACMG/AMP criteria and confirmed by Sanger sequencing, co-segregation analysis, and consistency with related phenotypes. Ocular clinical data were thoroughly reviewed, especially fundus changes. Results: A total of seven pathogenic variants in four of the 20 genes were detected in six probands from six families, including three with hemizygous nonsense variants p.(Q308*), p.(Q416*), and p.(R550*) in MSN, one with homozygous nonsense variants p.(R257*) in AIRE, one with compound heterozygous nonsense variants p.(R176*) and p.(T902*) in LAMB2, and one with a known c.1222T>C (p.W408R) heterozygous variant in CBL. Ocular presentation, as the initial signs of the diseases, was mainly retinopathy mimicking other forms of hereditary retinal degeneration, including exudative vitreoretinopathy in the three patients with MSN variants or tapetoretinal degeneration in the other three patients. Neither extraocular symptoms nor extraocular manifestations were recorded at the time of visit to our eye clinic. However, of the 19 families in the literature with retinopathy caused by variants in these four genes, only one family with an AIRE homozygous variant had retinopathy as an initial symptom, while the other 18 families had systemic abnormalities that preceded retinopathy. Discussion: This study, for the first time, identified six unrelated patients with retinopathy as their initial and only presenting sign of HID, contrary to the previous reports where retinopathy was the accompanying sign of systemic HID. Recognizing such phenotype of HID may facilitate the clinical care of these patients. Follow-up visits to such patients and additional studies are expected to validate and confirm our findings.

Clinical and Genetic Features of NR2E3-Associated Retinopathy: A Report of Eight Families with a Longitudinal Study and Literature Review.

(1) Background: NR2E3 encodes a nuclear receptor transcription factor that is considered to promote cell differentiation, affect retinal development, and regulate phototransduction in rods and cones. This study aimed to analyze the clinical characteristics and observe the prognosis of autosomal dominant retinopathy (ADRP) and autosomal recessive retinopathy (ARRP) associated with NR2E3; (2) Methods: NR2E3 variants were collected from our exome sequencing data and identified per the American College of Medical Genetics and Genomics criteria. Data from our cohort and a systemic literature review were conducted to explore the NR2E3 variants spectrum and potential genotype-phenotype correlations; (3) Results: Nine pathogenic variants/likely pathogenic variants in NR2E3, including five novel variants, were detected in eight families (four each with ADRP and ARRP). Follow-up data showed schisis/atrophy in the macula and retinal degeneration initiation around the vascular arcades with differences in ADRP and ARRP. A systemic literature review indicated patients with ADRP presented better visual acuity (p < 0.01) and later onset age (p < 0.0001) than did those with ARRP; (4) Conclusions: Macular schisis and retinal degeneration around vascular arcades may present as the prognosis of NR2E3-retinopathy, dominant, or recessive. Our data might further enrich our understanding of NR2E3 variants and associated inherited retinopathy.

A case of LSS-associated congenital nuclear cataract with hypotrichosis and literature review.

Congenital cataract is the most common cause of lifelong visual loss in children worldwide, which has significant genotypic and phenotypic heterogeneity. The LSS gene encodes lanosterol synthase (LSS), which acts on the cholesterol biosynthesis pathway by converting (S)-2,3-oxidosqualene to lanosterol. The biallelic pathogenic variants in the LSS gene were found in congenital cataract, Alopecia-intellectual disability syndrome, hypotrichosis simplex, and mutilating palmoplantar keratoderma. In this study, we reported the first congenital nuclear cataract combined with hypotrichosis in a 12-year-old boy with biallelic LSS variants (c.1025T>G; p.I342S and c.1531_1532insT; p.L511Ffs*17) by exome sequencing. Reviewing all reported patients with LSS variants indicated that p.W629 might be a hotspot for hypospadias and p.I342S was associated with congenital cataract. Patients with one or two truncation variants tend to have multisystem symptoms compared with those with two missense variants. These findings deepen the understanding of LSS variants and contribute to the genetic counseling of affected families.

Generation of an induced pluripotent stem cell line (ZSZOCi001-A) from a patient with Knobloch syndrome caused by biallelic mutations in the gene COL18A1.

Knobloch syndrome is an autosomal recessive disorder characterized by high myopia, retinal detachment, and occipital skull defects. Mutations in the COL18A1 gene have been identified to cause KNO1. Here, we successfully generated a human induced pluripotent stem cell (hiPSC) line from the peripheral blood mononuclear cells (PBMCs) of a KNO patient caused by COL18A1 biallelic pathogenic variants, and this iPSC model offers a precious disease model to study the pathological mechanism and possible treatment of KNO in vitro.

Non-Pharmaceutical Interventions against COVID-19 Causing a Lower Trend in Age of LHON Onset.

Leber hereditary optic neuropathy (LHON) is a monogenic but multifactorial disease vulnerable to environmental triggers. Little is known about how LHON onset changed during the COVID-19 pandemic and how non-pharmaceutical interventions (NPHIs) against COVID-19 impact LHON onset. One hundred and forty-seven LHON patients with the m.11778G>A mutation complaining of vision loss were involved between January 2017 and July 2022. The onset time points, age of onset, and possible risk factors were evaluated. Analyses were conducted among 96 LHON patients in the Pre-COVID-19 group and 51 in the COVID-19 group. The median (IQR) age of onset decreased significantly from 16.65 (13.739, 23.02) in pre-COVID-19 to 14.17 (8.87, 20.29) during COVID-19. Compared with the Pre-COVID-19 group, the COVID-19 group exhibited bimodal distribution with an additional peak at six; the first quarter of 2020 also witnessed a relatively denser onset, with no subsequent second spike. NPHIs against COVID-19 significantly changed patients' lifestyles, including higher secondhand smoke exposure (p < 0.001), adherence to masks (p < 0.001), reduction in time spent outdoors for leisure (p = 0.001), and prolonged screen time (p = 0.007). Multivariate logistic regression revealed that secondhand smoke exposure and mask-wearing were independent risk factors of younger LHON onset. Lower age of onset of LHON appeared after the breakout of the COVID-19 pandemic, and novel risk factors were detected, including secondhand exposure and long mask-wearing. Carriers of LHON mtDNA mutations, especially teenagers or children, should be advised to avoid secondhand smoke exposure and there are possible adverse outcomes of longer mask-wearing.

FDXR-Associated Oculopathy: Congenital Amaurosis and Early-Onset Severe Retinal Dystrophy as Common Presenting Features in a Chinese Population.

Variants in FDXR reportedly cause autosomal recessive auditory neuropathy and optic atrophy, expanding to retinal dystrophy. This study aimed to further clarify associated phenotypes. FDXR variants were selected from our in-house whole-exome sequencing dataset of 6397 families with different eye conditions. The clinical data of the identified patients were summarized. Biallelic pathogenic or likely pathogenic FDXR variants were identified in 11 unrelated patients, including 14 missense variants of which 10 were novel. Fundus observation showed complete optic disc pallor, silver wiring or severe attenuation of retinal vessels, and varying degrees of generalized retinal degeneration. Before the detection of FDXR variants, four patients were clinically diagnosed as congenital amaurosis due to the presence of nystagmus a few months after birth, while seven were diagnosed as early-onset severe retinal dystrophy due to the presence of nyctalopia and/or poor vision in early childhood. Biallelic FDXR variants are a frequent cause of congenital or early-onset severe retinal dystrophy, especially for patients with severe optic atrophy and retinal dystrophy in early childhood.

Unique Haplotypes in OPN1LW as a Common Cause of High Myopia With or Without Protanopia: A Potential Window Into Myopic Mechanism.

Purpose: Specific haplotypes (LVAVA, LIVVA, and LIAVA) formed by five polymorphisms (p.L153M, p.V171I, p.A174V, p.I178V, and p.S180A in exon 3 of OPN1LW) that cause partial or complete exon skipping have been reported as unique genetic causes of high myopia with or without colorblindness. This study aimed to identify the contribution of OPN1LW to early-onset high myopia (eoHM) and the molecular basis underlying eoHM with or without colorblindness. Methods: Comparative analysis of exome sequencing data was conducted for 1226 families with eoHM and 9304 families with other eye conditions. OPN1LW variants detected by targeted or whole exome sequencing were confirmed by long-range amplification and Sanger sequencing, together with segregation analysis. The clinical data were thoroughly analyzed. Results: Unique haplotypes and truncation variants in OPN1LW were detected exclusively in 68 of 1226 families with eoHM but in none of the 9304 families with other visual diseases (P = 1.63 × 10-63). Four classes of variants were identified: haplotypes causing partial splicing defects in OPN1LW (LVAVA or LIVVA in 31 families), LVAVA in OPN1LW-OPN1MW hybrid gene (in 3 families), LIAVA in OPN1LW (in 29 families), and truncations in OPN1LW (in 5 families). The first class causes partial loss of red photopigments, whereas the latter three result in complete loss of red photopigments. This is different from the replacement of red with green owing to unequal re-arrangement causing red-green colorblindness alone. Of the 68 families, 42 affected male patients (31 families) with the first class of variants (LVAVA or LIVVA in OPN1LW) had eoHM alone, whereas 37 male patients with the latter 3 classes had eoHM with protanopia. Adaptive optics retinal imaging demonstrated reduced cone regularity and density in men with eoHM caused by OPN1LW variants compared to those patients with eoHM and without OPN1LW variants. Conclusion: Based on the 68 families with unique variants in OPN1LW, our study provides firm evidence that the two different phenotypes (eoHM with or without colorblindness) are caused by two different classes of variants (partial splicing-effect haplotypes or complete splicing-effect haplotypes/truncation variants, respectively). The contribution of OPN1LW to eoHM (isolated and syndromic) was characterized by OPN1LW variants found in 5.5% (68/1226) of the eoHM families, making it the second most common cause of monogenic eoHM alone (2.4%) and a frequent cause of syndromic monogenic eoHM with colorblindness. Such haplotypes, in which each individual variant alone is considered a benign polymorphism, are potential candidates for other hereditary diseases with causes of missing genetic defects.

New Insight into the Genotype-Phenotype Correlation of PRPH2-Related Diseases Based on a Large Chinese Cohort and Literature Review.

Variants in PRPH2 are a common cause of inherited retinal dystrophies with high genetic and phenotypic heterogeneity. In this study, variants in PRPH2 were selected from in-house exome sequencing data, and all reported PRPH2 variants were evaluated with the assistance of online prediction tools and the comparative validation of large datasets. All variants were classified based on the American College of Medical Genetics and Genomics/Association for Molecular Pathology (ACMG/AMP) guidelines. Individuals with pathogenic or likely pathogenic variants of PRPH2 were confirmed by Sanger sequencing. Clinical characteristics were summarized. Ten pathogenic or likely pathogenic variants of PRPH2 were identified in 14 families. In our cohort, the most frequent variant was p.G305Afs*19, accounting for 33.3% (5/15) of alleles, in contrast to the literature, where p.R172G (11.6%, 119/1028) was the most common variant. Nine in-house families (63.8%) were diagnosed with retinitis pigmentosa (RP), distinct from the phenotypic spectrum in the literature, which shows that RP accounts for 27.9% (283/1013) and macular degeneration is more common (45.2%, 458/1013). Patients carrying missense variants predicted as damaging by all seven prediction tools and absent in the gnomAD database were more likely to develop RP compared to those carrying missense variants predicted as damaging with fewer tools or with more than one allele number in the gnomAD database (p = 0.001). The population-specific genetic and phenotypic spectra of PRPH2 were explored, and novel insight into the genotype-phenotype correlation of PRPH2 was proposed. These findings demonstrated the importance of assessing PRPH2 variants in distinct populations and the value of providing practical suggestions for the genetic interpretation of PRPH2 variants.

The Genetic Confirmation and Clinical Characterization of LOXL3-Associated MYP28: A Common Type of Recessive Extreme High Myopia.

Purpose: In previous studies, biallelic LOXL3 variants have been shown to cause autosomal recessive Stickler syndrome in one Saudi Arabian family or autosomal recessive early-onset high myopia (eoHM, MYP28) in two Chinese families. The current study aims to elucidate the clinical and genetic features of LOXL3-associated MYP28 in seven new families and two previously published families. Methods: LOXL3 variants were detected based on the exome sequencing data of 8389 unrelated probands with various ocular conditions. Biallelic variants were identified through multiple online bioinformatic tools, comparative analysis, and co-segregation analysis. The available clinical data were summarized. Results: Biallelic LOXL3 variants were exclusively identified in nine of 1226 families with eoHM but in none of the 7163 families without eoHM (P = 2.97 × 10-8, Fisher's exact test), including seven new and two previously reported families. Seven pathogenic variants were detected, including one nonsense (c.1765C>T/p.Arg589*), three frameshift (c.39dupG/p.Leu14Alafs*21; c.544delC/p.Leu182Cysfs*3, c.594delG/p.Gln199Lysfs*35), and three missense (c.371G>A/p.Cys124Tyr; c.1051G>A/p.Gly351Arg; c.1669G>A/p.Glu557Lys) variants. Clinical data of nine patients from nine unrelated families revealed myopia at the first visit at about 5 years of age, showing slow progression with age. Visual acuity at the last visit ranged from 0.04 to 0.9 (median age at last visit = 5 years, range 3.5-15 years). High myopic fundus changes, observed in all nine patients, were classified as tessellated fundus (C1) in five patients and diffuse choroidal atrophy (C2) in four patients. Electroretinograms showed mildly reduced cone responses and normal rod responses. Except for high myopia, no other specific features were shared by these patients. Conclusions: Biallelic LOXL3 variants exclusively presenting in nine unrelated patients with eoHM provide firm evidence implicating MYP28, with an estimated prevalence of 7.3 × 10-3 in eoHM and of about 7.3 × 10-5 in the general population for LOXL3-associated eoHM. So far, MYP28 represents a common type of autosomal recessive extreme eoHM, with a frequency comparable to LRPAP1-associated MYP23.

Pathogenic Variants in CEP290 or IQCB1 Cause Earlier-Onset Retinopathy in Senior-Loken Syndrome Compared to Those in INVS, NPHP3, or NPHP4.

PURPOSE: Senior-Loken syndrome (SLSN) is an autosomal recessive disorder characterized by retinopathy and nephronophthisis. This study aimed to evaluate whether different phenotypes are associated with different variants or subsets of 10 SLSN-associated genes based on an in-house data set and a literature review. DESIGN: Retrospective case series. METHODS: Patients with biallelic variants in SLSN-associated genes, including NPHP1, INVS, NPHP3, NPHP4, IQCB1, CEP290, SDCCAG8, WDR19, CEP164, and TRAF3IP1, were recruited. Ocular phenotypes and nephrology medical records were collected for comprehensive analysis. RESULTS: Variants in 5 genes were identified in 74 patients from 70 unrelated families, including CEP290 (61.4%), IQCB1 (28.6%), NPHP1 (4.2%), NPHP4 (2.9%), and WDR19 (2.9%). The median age at the onset of retinopathy was approximately 1 month (since birth). Nystagmus was the most common initial sign in patients with CEP290 (28 of 44, 63.6%) or IQCB1 (19 of 22, 86.4%) variants. Cone and rod responses were extinguished in 53 of 55 patients (96.4%). Characteristic fundus changes were observed in CEP290- and IQCB1-associated patients. During follow-up, 70 of the 74 patients were referred to nephrology, among whom nephronophthisis was not detected in 62 patients (88.6%) at a median age of 6 years but presented in 8 patients (11.4%) aged approximately 9 years. CONCLUSIONS: Patients with pathogenic variants in CEP290 or IQCB1 presented early with retinopathy, whereas other patients with INVS, NPHP3, or NPHP4 variants first developed nephropathy. Therefore, awareness of the genetic and clinical features may facilitate the clinical management of SLSN, especially early intervention of kidney problems for patients with eyes affected first.

Missense Mutations in MAB21L1: Causation of Novel Autosomal Dominant Ocular BAMD Syndrome.

Purpose: Biallelic MAB21L1 variants have been reported to cause autosomal recessive cerebellar, ocular, craniofacial, and genital syndrome (COFG), whereas only five heterozygous pathogenic variants have been suspected to cause autosomal dominant (AD) microphthalmia and aniridia in eight families. This study aimed to report an AD ocular syndrome (blepharophimosis plus anterior segment and macular dysgenesis [BAMD]) syndrome based on clinical and genetic findings from patients with monoallelic MAB21L1 pathogenic variants in our cohort and reported cases. Methods: Potential pathogenic variants in MAB21L1 were detected from a large in-house exome sequencing dataset. Ocular phenotypes of the patients with potential pathogenic variants in MAB21L1 were summarized, and the genotype-phenotype correlation was analyzed through a comprehensive literature review. Results: Three heterozygous missense variants in MAB21L1, predicted to be damaging, were detected in 5 unrelated families, including c.152G>T in 2, c.152G>A in 2, and c.155T>G in one. All were absent from gnomAD. The variants were de novo in two families, transmitted from affected parents to offspring in two families, and with an unknown origin in the other family, demonstrating strong evidence of AD inheritance. All patients revealed similar BAMD phenotypes, including blepharophimosis, anterior segment dysgenesis, and macular dysgenesis. Genotype-phenotype analysis suggested that patients with monoallelic MAB21L1 missense variants had only ocular anomalies (BAMD), whereas patients with biallelic variants presented both ocular and extraocular symptoms. Conclusions: Heterozygous pathogenic variants in MAB21L1 account for a new AD BAMD syndrome, which is completely different from COFG caused by homozygous variants in MAB21L1. Nucleotide c.152 is likely a mutation hot spot, and the encoded residue of p.Arg51 might be critical for MAB21L1.

Variant Landscape of 15 Genes Involved in Corneal Dystrophies: Report of 30 Families and Comprehensive Analysis of the Literature.

Corneal dystrophies (CDs) represent a group of inherited diseases characterized by the progressive deposit of abnormal materials in the cornea. This study aimed to describe the variant landscape of 15 genes responsible for CDs based on a cohort of Chinese families and a comparative analysis of literature reports. Families with CDs were recruited from our eye clinic. Their genomic DNA was analyzed using exome sequencing. The detected variants were filtered using multi-step bioinformatics and confirmed using Sanger sequencing. Previously reported variants in the literature were summarized and evaluated based on the gnomAD database and in-house exome data. In 30 of 37 families with CDs, 17 pathogenic or likely pathogenic variants were detected in 4 of the 15 genes, including TGFBI, CHST6, SLC4A11, and ZEB1. A comparative analysis of large datasets revealed that 12 of the 586 reported variants are unlikely causative of CDs in monogenic mode, accounting for 61 of 2933 families in the literature. Of the 15 genes, the gene most frequently implicated in CDs was TGFBI (1823/2902, 62.82% of families), followed by CHST6 (483/2902, 16.64%) and SLC4A11 (201/2902, 6.93%). This study presents, for the first time, the landscape of pathogenic and likely pathogenic variants in the 15 genes responsible for CDs. Awareness of frequently misinterpreted variants, such as c.1501C>A, p.(Pro501Thr) in TGFBI, is crucial in the era of genomic medicine.

Clinical and genetic features of retinoschisis in 120 families with RS1 mutations.

BACKGROUND/AIMS: X-linked retinoschisis (XLRS), associated with RS1, is the most common type of X-linked retinopathy in children. This study aimed to identify clinical and genetic features of retinoschisis in 120 families with RS1 variants in China. METHODS: RS1 variants were collected from our in-house exome data and were predicted by multiple-step bioinformatics analysis. Clinical data of 122 patients from 120 families with potential pathogenic RS1 variants were analysed and summarised, respectively. RESULT: Totally, 79 hemizygous variants (53 missense, 25 truncation and 1 indel), were detected. All except one (78/79, 98.7%), including 22 novels, were classified as potential pathogenic and detected exclusively in 120 families with retinoschisis. Clinical data demonstrated an average age of presentation at 5 years (1 month-41 years). Macular changes were classified as macular schisis (87.5%), macular atrophy (10.7%), normal (0.9%) and unclassified (0.9%). Patients with macular atrophy had older age but similar visual acuity compared with macular schisis. Peripheral retinal changes included flat retinoschisis (52.4%), bullous retinoschisis (BRS) (10.7%) and normal-like (36.9%) patients. Spontaneous regression was observed in two patients with BRS on follow-up examination. Visual acuity in the peripheral retinoschisis group was worse than that without peripheral retinoschisis. CONCLUSION: Almost all rare RS1 variants were potential pathogenic. All patients with RS1 pathogenic variants showed detectable characteristics in the macula and/or peripheral retina. Our data on RS1 variants and associated clinical phenotypes may be of value for clinical diagnosis and genetic test of retinoschisis.

Genetic and clinical landscape of ARR3-associated MYP26: the most common cause of Mendelian early-onset high myopia with a unique inheritance.

AIMS: To elucidate genetic background of early-onset high myopia (eoHM) and characteristics of ARR3-associated MYP26. METHODS: Variants in 14 genes reported to contribute to eoHM, including ARR3, were selected from exome sequencing data set and classified into different categories following American College of Medical Genetics and Genomics guidelines based on in silico prediction, associated phenotypes, confirmation and cosegregation analysis. The available clinical data of individuals were summarised. RESULTS: Pathogenic and likely pathogenic variants in three of 14 genes were identified in 52 of 928 families with eoHM, including 29 in ARR3, 22 in OPN1LW and 1 in LRPAP1. For ARR3, 24 pathogenic variants (16 truncation and 8 missense) were identified in 66 women and 12 men, in whom 64 women and 4 men had eoHM by X-linked female-limited inheritance. Refraction ranged from -5.00 to -28.75 diopter (-12.58±4.83). Mild-to-moderately reduced cone responses were recorded in 76.9% (10/13) of patients with electroretinogram recordings. Most patients (75.9%, 41/54) had mild myopic fundus changes (C0 to C1). Genotype-phenotype analysis suggested that the myopic retinopathy degree was correlated with age and the variant's nature. Peripheral retinal degeneration was observed in 38.5% (5/13) patients using wide-field examinations. CONCLUSION: This study reveals ARR3 as the most frequently implicated gene for Mendelian eoHM. Truncations and highly scored missense variants in ARR3 are pathogenic. Myopia due to ARR3 mutations is transmitted in X-linked female-limited inheritance, manifests with mild cone impairment and slowly progresses to pathologic myopia. Identification of the most common cause for Mendelian eoHM provides a valuable starting point into the molecular mechanism of myopia.