Genetics of Retinitis Pigmentosa and Other Hereditary Retinal Disorders in Western Switzerland.

INTRODUCTION: Mutational screening of inherited retinal disorders is prerequisite for gene targeted therapy. Our aim was to report and analyze the proportions of mutations in inherited retinal disease (IRD)-causing genes from a single center in Switzerland in order to describe the distribution of IRDs in Western Switzerland. METHODS: We conducted a retrospective study of patient records. Criteria for inclusion were residence in Western Switzerland for patients and relatives presenting a clinical diagnosis of IRDs and an established molecular diagnosis managed by the genetics service of the Jules-Gonin Eye Hospital (JGEH) of Lausanne between January 2002 and December 2022. We initially investigated the IRD phenotypes in all patients (full cohort) with a clinical diagnosis, then calculated the distribution of IRD gene mutations in the entire cohort (genetically determined cohort). We analyzed a sub-group that comprised pediatric patients (≤18 years of age). In addition, we calculated the distribution of gene mutations within the most represented IRDs. Comprehensive gene screening was performed using a combined approach of different generation of DNA microarray analysis, direct sequencing, and Sanger sequencing. RESULTS: The full cohort comprised 899 individuals from 690 families with a clinical diagnosis of IRDs. We identified 400 individuals from 285 families with an elucidated molecular diagnosis (variants in 84 genes) in the genetically determined cohort. The pediatric cohort included 89 individuals from 65 families with an elucidated molecular diagnosis. The molecular diagnosis rate for the genetically determined cohort was 58.2% (family ratio) and the 5 most frequently implicated genes per family were ABCA4 (11.6%), USH2A (7.4%), EYS (6.7%), PRPH2 (6.3%), and BEST1 (4.6%). The pediatric cohort had a family molecular diagnosis rate of 64.4% and the 5 most common mutated genes per family were RS1 (9.2%), ABCA4 (7.7%), CNGB3 (7.7%), CACNA1F (6.2%), CEP290 (4.6%). CONCLUSIONS: This study describes the genetic mutation landscape of IRDs in Western Switzerland in order to quantify their disease burden and contribute to a better orientation of the development of future gene targeted therapies.

Analysis of Suspected Achromatopsia by Multimodal Diagnostic Testing.

BACKGROUND: Achromatopsia (ACHM) as a hereditary cone disease might manifest in a stationary and progressive manner. The proper clinical and genetic diagnosis may allow an individual prognosis, accurate genetic counselling, and the optimal choice of low vision aids. The primary aim of the study was to determine the spectrum of clinical and genetic diagnostics required to characterize the ACHM. METHODS: A retrospective analysis was performed in 8 patients from non-related families (5 ♀,3 ♂); age at diagnosis: 3 - 56 y, mean 18.13 (SD ± 18.22). Clinical phenotyping, supported by colour vision test, fundus photography-, autofluorescence- (FAF), infra-red- (IR), OCT imaging and electroretinography provided information on the current status and the course of the disease over the years. In addition, genetic examinations were performed with ACHM relevant testing (CNGA3, CNGB3, GNAT2, PDE6C, PDE6H and the transcription factor ATF6). RESULTS: All patients suffered photophobia and reduced visual acuity (mean: 0.16 [SD ± 0.08]). Nystagmus was identified in 7 from 8 subjects and in one patient a head-turn right helped to reduce the nystagmus amplitude. Colour vision testing confirmed complete achromatopsia in 7 out of 8 patients. Electrophysiology found severely reduced photopic- but also scotopic responses. Thinning and interruption of the inner segment ellipsoid (ISe) line within the macula but also FAF- and IR abnormalities in the fovea and/or parafovea were characteristic in all ACHM patients. Identification of pathogenic mutations in 7 patients helped to confirm the diagnosis of ACHM (3 adults, 4 children; 3 ♀ and 4 ♂). Achromatopsia was linked to CNGA3 (2 ♀, 1 ♂) and CNGB3 variants (2 ♀, 3 ♂). The youngest patient (♀, 10 y) had 3 different CNGB3 variants on different alleles. In a patient (♂, 29 y) carrying 2 pathogenic digenic-triallelic CNGA3- and CNGB3-mutations, a severe progression of ISe discontinuity to coloboma-like macular atrophy was observed during the 12-year follow-up. The oldest female (67 y) showed a compound homozygous CNGA3- and heterozygous CNGB3-, as well as a heterozygous GUCY2D variants. The destruction of her ISe line was significantly enlarged and represented a progressive cone-rod phenotype in comparison to other ACHM patients. In a patient (♂, 45 y) carrying a pathogenic CNGB3 and USH2 mutation, a severe macular oedema and a rod-cone phenotype was observed. In addition, two variants in C2ORF71 considered as VOS were found. One patient showed the rare ATF6 mutation, where a severe coloboma-like macular atrophy was observed on the left eye as early as at the age of three years. CONCLUSION: Combining multimodal ophthalmological diagnostics and molecular genetics when evaluating patients with ACHM helps in characterizing the disease and associated modifiers, and is therefore strongly recommended for such patients.

Incomplete Recovery of Zebrafish Retina Following Cryoinjury.

Zebrafish show an extraordinary potential for regeneration in several organs from fins to central nervous system. Most impressively, the outcome of an injury results in a near perfect regeneration and a full functional recovery. Indeed, among the various injury paradigms previously tested in the field of zebrafish retina regeneration, a perfect layered structure is observed after one month of recovery in most of the reported cases. In this study, we applied cryoinjury to the zebrafish eye. We show that retina exposed to this treatment for one second undergoes an acute damage affecting all retinal cell types, followed by a phase of limited tissue remodeling and regrowth. Surprisingly, zebrafish developed a persistent retinal dysplasia observable through 300 days post-injury. There is no indication of fibrosis during the regeneration period, contrary to the regeneration process after cryoinjury to the zebrafish cardiac ventricle. RNA sequencing analysis of injured retinas at different time points has uncovered enriched processes and a number of potential candidate genes. By means of this simple, time and cost-effective technique, we propose a zebrafish injury model that displays a unique inability to completely recover following focal retinal damage; an outcome that is unreported to our knowledge. Furthermore, RNA sequencing proved to be useful in identifying pathways, which may play a crucial role not only in the regeneration of the retina, but in the first initial step of regeneration, degeneration. We propose that this model may prove useful in comparative and translational studies to examine critical pathways for successful regeneration.

Contribution of Whole-Genome Sequencing and Transcript Analysis to Decipher Retinal Diseases Associated with MFSD8 Variants.

Biallelic gene defects in MFSD8 are not only a cause of the late-infantile form of neuronal ceroid lipofuscinosis, but also of rare isolated retinal degeneration. We report clinical and genetic data of seven patients compound heterozygous or homozygous for variants in MFSD8, issued from a French cohort with inherited retinal degeneration, and two additional patients retrieved from a Swiss cohort. Next-generation sequencing of large panels combined with whole-genome sequencing allowed for the identification of twelve variants from which seven were novel. Among them were one deep intronic variant c.998+1669A>G, one large deletion encompassing exon 9 and 10, and a silent change c.750A>G. Transcript analysis performed on patients' lymphoblastoid cell lines revealed the creation of a donor splice site by c.998+1669A>G, resulting in a 140 bp pseudoexon insertion in intron 10. Variant c.750A>G produced exon 8 skipping. In silico and in cellulo studies of these variants allowed us to assign the pathogenic effect, and showed that the combination of at least one severe variant with a moderate one leads to isolated retinal dystrophy, whereas the combination in trans of two severe variants is responsible for early onset severe retinal dystrophy in the context of late-infantile neuronal ceroid lipofuscinosis.

Premature Vertebral Mineralization in hmx1-Mutant Zebrafish.

H6 family homeobox 1 (HMX1) regulates multiple aspects of craniofacial development, and mutations in HMX1 are linked to an ocular defect termed oculoauricular syndrome of Schorderet-Munier-Franceschetti (OAS) (MIM #612109). Recently, additional altered orofacial features have been reported, including short mandibular rami, asymmetry of the jaws, and altered premaxilla. We found that in two mutant zebrafish lines termed hmx1mut10 and hmx1mut150, precocious mineralization of the proximal vertebrae occurred. Zebrafish hmx1mut10 and hmx1mut150 report mutations in the SD1 and HD domains, which are essential for dimerization and activity of hmx1. In hmx1mut10, the bone morphogenetic protein (BMP) antagonists chordin and noggin1 were downregulated, while bmp2b and bmp4 were highly expressed and specifically localized to the dorsal region prior to the initiation of the osteogenic process. The osteogenic promoters runx2b and spp1 were also upregulated. Supplementation with DMH1-an inhibitor of the BMP signaling pathway-at the specific stage in which bmp2b and bmp4 are highly expressed resulted in reduced vertebral mineralization, resembling the wildtype mineralization progress of the axial skeleton. These results point to a possible role of hmx1 as part of a complex gene network that inhibits bmp2b and bmp4 in the dorsal region, thus regulating early axial skeleton development.

New COL6A6 Variant Causes Autosomal Dominant Retinitis Pigmentosa in a Four-Generation Family.

Purpose: To report that variants in the gene for a large lamina basal component protein, COL6A6 (collagen type VI alpha 6 chain, Col6α6), linked to chromosome 3p22.1 causes retinitis pigmentosa (RP) in patients with autosomal dominant transmission (adRP). Methods: A positional-cloning approach, whole exome sequencing, and modeling were used. The proband and several affected family members have been phenotyped and followed for over 12 years. Results: A heterozygous missense variant, c.509C>G (p. Ser170Cys) in exon 2 of COL6A6 (comprised of 36 exons and 2236 amino acids), was observed in a four- generation family and is likely to cause the adRP phenotype. It was identified in 10 affected members. All affected family members had a distinct phenotype: late-onset rod cone dystrophy, with good retained visual acuity, until their late 70s. Immunohistochemistry of human retina showed a dot-like signal at the base of the inner segments of photoreceptors and outer plexiform layer (OPL). The structural modeling of the N7 domain of Col6α6 suggests that the mutant might result in the abnormal cellular localization of collagen VI or malformation of collagen fibers resulting in the loss of its unique filament structure. Conclusions: COL6A6 is widely expressed in human tissues and evolutionary conserved. It is thought to interact with a range of extracellular matrix components. Our findings suggest that this form of RP has long-term useful central visual acuity and a mild progression, which are important considerations for patient counseling.

OCT-angiography assessing quiescent and active choroidal neovascularization in retinitis pigmentosa associated with PRPH2 pathogenic variant.

PURPOSE: To report multimodal imaging findings including optical coherence tomography angiography (OCT-A) of a patient presenting with a quiescent choroidal neovascularization (CNV) in one eye and an active CNV in the fellow eye, complicating retinitis pigmentosa (RP) linked to PRPH2 pathogenic variant, with follow-up and management of both eyes. METHODS: Observational case report. RESULTS: A 40-year-old female with history of autosomal dominant RP consulted for acute visual loss in her right eye (RE). Multimodal imaging including OCT-A confirmed the diagnosis of active type 2 CNV in the RE and highlighted an incidental asymptomatic non-exudative "quiescent" CNV in the left eye (LE). This complication was managed by intra-vitreal Bevacizumab injections in the RE and regular monitoring of the LE. Frequent follow-up could detect early CNV activation signs in LE allowing early treatment. Mutation analysis of PRPH2 exons identified a known heterozygous pathogenic missense variation c.646C>T, p.P216S in exon 2. CONCLUSION: Multimodal imaging and especially OCT-A can be of a great help in the diagnosis and the management of CNV complicating RP, even at the stage of quiescent CNV. In presence of neovascular complication, PRPH2 gene should be investigated because of its frequent macular involvement despite high phenotypic variability.

Macular Dystrophy with Bilateral Macular Telangiectasia Related to the CYP2U1 Pathogenic Variant Assessed with Multimodal Imaging Including OCT-Angiography.

PURPOSE: We report the case of a neurologically asymptomatic young boy presenting with an unusual phenotype of CYP2U1 related macular dystrophy associating bilateral macular telangiectasia (MacTel) and fibrotic choroidal neovascularization (CNV), assessed with complete multimodal imaging including optical coherence tomography angiography (OCT-A). CASE PRESENTATION: A twelve-year-old boy from a non-consanguineous family complained of bilateral progressive visual loss and photophobia. The best-corrected visual acuity was 2/10 on the right eye and 3/10 on the left eye. Fundus examination showed central pigmented fibrotic macular scar and yellowish punctuate deposits in both eyes. En face OCT-A detected typical macular telangiectasia (MacTel) in both eyes with dilated telangiectatic capillaries in the deep capillary plexus associated with vascular anomalies in the superficial and deep capillary plexus. Typical hypo-reflective cavities were observed within the inner foveal layers on structural OCT. En face OCT-A also confirmed the presence of bilateral inactive CNV within the fibrotic scars, showing high-flow vascular network at the level of the subretinal hyperreflective lesions. Whole exome sequencing identified a known homozygous pathogenic variant in CYP2U1 gene (c.1168C > T, p.Arg390*), which is a disease-causing mutation in autosomal recessive spastic paraplegia type 56 (SPG56). The neurological examination was normal, and electromyography and brain magnetic resonance imaging were unremarkable as well. CONCLUSION: Macular dystrophy can be the first manifestation in SPG56. A particular phenotype with MacTel was observed, and neovascular complications are possible. CYP2U1 should be included in the panels of genes tested for macular dystrophies, especially in the presence of MacTel and/or neurological manifestations.

Crystals deposits in the anterior and posterior lens cortex in Bietti corneo-retinal dystrophy.

BACKGROUND: Whereas crystals deposit in the retina, the cornea and limbus in Bietty corneo-retinal dystrophy (BCD) is now well established and documented, only two published cases report their findings in the lens and no cases deep in the lens cortex. MATERIAL AND METHODS: Four consecutive adult patients from three different unrelated families presenting lens crystals associated with advanced genetically confirmed BCD were enrolled with advanced disease and long follow up (>12 years). Demographics, visual acuity, slit lamp biomicroscopy, lens and posterior pole photography, optical coherence tomography (OCT), autofluorescence, and screening for CYP4V2 type of mutation were performed. The setting was Jules Gonin Eye Hospital, Switzerland, between 1.1 2013 and 1.11. 2019. RESULTS: All patients were European women. The ages ranged from 40 to 81 years. Best Snellen visual acuity ranged from light perception to 1.0. All patients presented with limbus and retinal crystals deposit that disappeared over time and the development of severe chorioretinal atrophy. With long-term follow up, multiple crystal-like deposits appeared in the anterior, posterior lens capsule and cortex. All patients, but one, had homozygous or compound heterozygous mutations in CYP4V2 gene. CONCLUSIONS: To the best of our knowledge, there are no published cases of crystal deposits in the cortex of the lens of patients diagnosed with BCD associated with CYP4V2 gene mutation. This could be a feature of advanced BCD, and their presence in the lens cortex questions the hypothesis of floating deposits from posterior pole although their exact etiology remains to be determined.

Piperlongumine promotes death of retinoblastoma cancer cells.

Retinoblastoma is the most common pediatric intraocular malignant tumor. While retinoblastoma initiation is triggered by the inactivation of both alleles of the retinoblastoma tumor suppressor gene (RB1) in the developing retina, tumor progression requires additional epigenetic changes, retinoblastoma genomes being quite stable. Although the management of RB has recently improved, new therapeutic agents are necessary to improve the treatment of advanced forms of retinoblastoma. In this report, we analyzed the pro-death effect of piperlongumine (PL), a natural compound isolated from Piper longum L., on two human retinoblastoma cell lines, WERI-Rb and Y79. The effects of PL on cell proliferation, cell death and cell cycle were investigated. PL effectively inhibited cell growth, impacted the cell cycle by decreasing the level of cyclins and CDK1 and increasing CDKN1A and triggered a caspase-3 independant cell death process in which reactive oxygen species (ROS) production is a major player. Indeed, PL toxicity in retinoblastoma cell lines was inhibited by a ROS scavenger N-acetyl-l-cysteine (NAC) treatment. These findings suggest that PL reduces tumor growth and induces cell death by regulating the cell cycle.

Homozygous mutation in ABCA4 associated with cone rod dystrophy in a patient with Turner syndrome.

PURPOSE: We report a special case of a patient who presented with two rare genetic diseases, Turner syndrome and cone-rod dystrophy (CRD), caused by mutation in the ABCA4 gene. METHODS: We present a case of a 12-year-old female with a progressive visual loss, poor night vision and short stature. We performed a clinical, karyotype of peripheral blood and molecular genetic study. DNA sample from the index patient was subjected to whole exome sequencing. Variants localized in homozygous regions were validated by Sanger sequencing. RESULTS: Fundus examination presented CRD phenotype and the general examination revealed short stature, aortic coarctation and infantile uterus, without visible ovaries on pelvic ultrasound. The karyotype of peripheral blood showed monosomy 45,X. We identified a known homozygous deletion c.[885delC];[885delC] in ABCA4, resulting in a frameshift at the position p.[L296Cfs*4];[ L296Cfs*4] . In addition, mutations in RPGR and ORF15 were excluded. CONCLUSIONS: Several ocular disorders are known to be associated with Turner syndrome, however, in this case, we hypothesize that CRD is not related to Turner syndrome but may be a manifestation of the lack of a normal X chromosome with ABCA4 mutation.

Different Phenotypes in Pseudodominant Inherited Retinal Dystrophies.

Retinal dystrophies (RD) are a group of Mendelian disorders caused by rare genetic variations leading to blindness. A pathogenic variant may manifest in both dominant or recessive mode and clinical and genetic heterogeneity makes it difficult to establish a precise diagnosis. In this study, families with autosomal dominant RD in successive generations were identified, and we aimed to determine the disease's molecular origin in these consanguineous families. Whole exome sequencing was performed in the index patient of each family. The aim was to determine whether these cases truly represented examples of dominantly inherited RD, or whether another mode of inheritance might be applicable. Six potentially pathogenic variants in four genes were identified in four families. In index patient with enhanced S-cone syndrome in F1, we identified a new digenetic combination: a heterozygous variant p.[G51A];[=] in RHO and a homozygous pathogenic variant p.[R311Q];[R311Q] in NR2E3. Helicoid subretinal fibrosis associated with recessive NR2E3 variant p.[R311Q];[R311Q] was identified in F2. A new frameshift variant c.[105delG];[105delG] in RDH12 was found in F3 with cone-rod dystrophy. In F4, the compound heterozygous variants p.[R964*];[W758*] were observed in IMPG2 with a retinitis pigmentosa (RP) phenotype. We showed that both affected parents and the offspring, were homozygous for the same variants in all four families. Our results provide evidence that in consanguineous families, autosomal recessive can be transmitted as pseudodominant inheritance in RD patients, and further extend our knowledge of pathogenic variants in RD genes.

Hmx1 regulates urfh1 expression in the craniofacial region in zebrafish.

H6 family homeobox 1 (HMX1) regulates multiple aspects of craniofacial development as it is widely expressed in the eye, peripheral ganglia and branchial arches. Mutations in HMX1 are linked to an ocular defect termed Oculo-auricular syndrome of Schorderet-Munier-Franceschetti (MIM #612109). We identified UHRF1 as a target of HMX1 during development. UHRF1 and its partner proteins actively regulate chromatin modifications and cellular proliferation. Luciferase assays and in situ hybridization analyses showed that HMX1 exerts a transcriptional inhibitory effect on UHRF1 and a modification of its expression pattern. Overexpression of hmx1 in hsp70-hmx1 zebrafish increased uhrf1 expression in the cranial region, while mutations in the hmx1 dimerization domains reduced uhrf1 expression. Moreover, the expression level of uhrf1 and its partner dnmt1 was increased in the eye field in response to hmx1 overexpression. These results indicate that hmx1 regulates uhrf1 expression and, potentially through regulating the expression of factors involved in DNA methylation, contribute to the development of the craniofacial region of zebrafish.

Genetic spectrum of retinal dystrophies in Tunisia.

We report the molecular basis of the largest Tunisian cohort with inherited retinal dystrophies (IRD) reported to date, identify disease-causing pathogenic variants and describe genotype-phenotype correlations. A subset of 26 families from a cohort of 73 families with clinical diagnosis of autosomal recessive IRD (AR-IRD) excluding Usher syndrome was analyzed by whole exome sequencing and autozygosity mapping. Causative pathogenic variants were identified in 50 families (68.4%), 42% of which were novel. The most prevalent pathogenic variants were observed in ABCA4 (14%) and RPE65, CRB1 and CERKL (8% each). 26 variants (8 novel and 18 known) in 19 genes were identified in 26 families (14 missense substitutions, 5 deletions, 4 nonsense pathogenic variants and 3 splice site variants), with further allelic heterogeneity arising from different pathogenic variants in the same gene. The most common phenotype in our cohort is retinitis pigmentosa (23%) and cone rod dystrophy (23%) followed by Leber congenital amaurosis (19.2%). We report the association of new disease phenotypes. This research was carried out in Tunisian patients with IRD in order to delineate the genetic population architecture.

Posterior staphylomas in non-highly myopic eyes with retinitis pigmentosa.

PURPOSE: Our aim was to highlight the presence and the frequency of posterior staphyloma (PS) in non-highly myopic retinitis pigmentosa (RP) patients and to study the relationship between PS and choroidal thickness (CT). METHODS: This was a retrospective case-control study of 77 eyes (39 patients) with RP, axial length inferior to 26 mm and clinically preserved macular area. All patients underwent fundus photography, A- and B-scan ocular ultrasonography, fundus autofluorescence (FAF) and swept source optical coherence tomography (SS-OCT). PS was defined by an outward bowing of the sclera on SS-OCT and B-scans. The relationship between the PS and SS-OCT layers thicknesses was determined. RESULTS: Over 77 RP eyes of 39 patients studied, a PS was identified in 17 eyes (22%) of nine patients. Fifteen eyes had a narrow macular staphyloma (NMS), and two eyes had a wide macular staphyloma (WMS). Mean age in this group was 34.2 years (range 19-53 years), mean axial length was 23.60 ± 0.61 mm and mean CT was 185.7 ± 71 um versus 259.7 um in eyes without PS. The staphyloma edges corresponded to area of outer retina loss on SS-OCT and were larger than the hyperautofluorescent ring on FAF. We found a significant association between PS and CT in our RP patients (p = 0.003). The mean CT was significantly thinner in PS eyes compared to eyes without staphyloma. There was no significant association between PS and with visual acuity, years of progression, retinal thickness nor FAF findings. CONCLUSIONS: PS was present in 22% of non-highly myopic eyes with RP. Narrow macular staphyloma was the most common type observed in our series. A marked thinning of the choroid was noted in PS eyes when compared to RP eyes without PS, as well as the outer retina degeneration.

Correction: Habibi I. et al. "Clinical and Genetic Findings of Autosomal Recessive Bestrophinopathy (ARB)" Genes, 2019, 10, 953.

The authors wish to make a correction to the published version of their paper [...].

Zebrafish: Housing and husbandry recommendations.

This article provides recommendations for the care of laboratory zebrafish (Danio rerio) as part of the further implementation of Annex A to the European Convention on the protection of vertebrate animals used for experimental and other scientific purposes, EU Commission Recommendation 2007/526/EC and the fulfilment of Article 33 of EU Directive 2010/63, both concerning the housing and care of experimental animals. The recommendations provide guidance on best practices and ranges of husbandry parameters within which zebrafish welfare, as well as reproducibility of experimental procedures, are assured. Husbandry procedures found today in zebrafish facilities are numerous. While the vast majority of these practices are perfectly acceptable in terms of zebrafish physiology and welfare, the reproducibility of experimental results could be improved by further standardisation of husbandry procedures and exchange of husbandry information between laboratories. Standardisation protocols providing ranges of husbandry parameters are likely to be more successful and appropriate than the implementation of a set of fixed guidance values neglecting the empirically successful daily routines of many facilities and will better reflect the wide range of environmental parameters that characterise the natural habitats occupied by zebrafish. A joint working group on zebrafish housing and husbandry recommendations, with members of the European Society for Fish Models in Biology and Medicine (EUFishBioMed) and of the Federation of European Laboratory Animal Science Associations (FELASA) has been given a mandate to provide guidelines based on a FELASA list of parameters, 'Terms of Reference'.

Mutations in VSX2, SOX2, and FOXE3 Identified in Patients with Micro-/Anophthalmia.

Anophthalmia and microphthalmia (A/M) are rare distinct phenotypes that represent a continuum of structural developmental eye defects. Here, we describe three probands from an Egyptian population with various forms of A/M: two patients with bilateral anophthalmia and one with bilateral microphthalmia that were investigated using whole exome sequencing (WES). We identified three causative mutations in three different genes. A new homozygous frameshift mutation c.[422delA];[422delA], p.[N141Ifs∗19];[N141Ifs∗19] in VSX2 was identified in a patient showing bilateral anophthalmia. A previously reported SOX2 deletion c.[70_89del20] p.[N24Rfs∗65];[=] was found in one subject with bilateral anophthalmia. A novel homozygous in-frame mutation c.[431_433delACT];[431_433delACT], p.[Y144del]; [Y144del]) in FOXE3 was identified in a patient with severe bilateral microphthalmia and anterior segment dysgenesis. This study shows that whole exome sequencing (WES) is a reliable and effective strategy for the molecular diagnosis of A/M. Our results expand its allelic heterogeneity and highlight the need for the testing of patient with this developmental anomaly.

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.

Analysis of Inherited Optic Neuropathies.

BACKGROUND: Inherited optic neuropathies (IONs) cover a spectrum of clinically and genetically heterogenic conditions. Genetic evaluation of patients with IONs may enable their better clinico-diagnostic assessment and management of the disease. The aim of the present study was to determine the genetic condition related to the phenotype in patients with diverse inherited optic neuropathies. PATIENTS AND METHODS: A retrospective study was performed in 12 adults and 8 children of 8 non-related families. Clinical phenotyping, supported by color fundus, FAF, and OCT imaging, was performed. Genetic testing was obtained for all family members suspected for ION. RESULTS: Identification of pathogenic mutations in eight non-related families helped to confirm the diagnosis of ION. Affected from ION were ten patients (eight adults and two children; four women and six men). Bilateral Leber's hereditary optic neuropathy (LHON) was linked to the m.11778G>A mutation in two families (two affected and five carriers). Secondary homoplasmic LHON mutations in MT-ND1 (m.4216T>C) and MT-CO3 genes (m.9804G>A) were confirmed in two families (each one subject, three eyes affected), without detection of a primary LHON mutation. One member presented a picture of right-sited optic neuropathy associated with a c.220C>G mutation in the ACO2 gene and a heterozygous c.185C>T mutation in the LDLR gene. Autosomal dominant optic atrophy was confirmed in three non-related families (five subjects with bilateral ION), where molecular genetic analyses confirmed four different heterozygous mutations in OPA1: c.1847+1G>T; c.2497-1G>A, 297A>G and c.(2983+1_2984-1)_(c.*3211) (2 splicing mutations, 1 missense mutation, and 1 gross deletion encompassing exons 30 and 31). CONCLUSIONS: Combining clinics and molecular genetics when evaluating patients with IONs helps in characterizing disease and, therefore, is strongly recommended for such patients.