Visual outcome measures in pediatric myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD)

BACKGROUND

Myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) comprises various age-dependent clinical phenotypes and may be monophasic, multiphasic, or chronic. Optic neuritis (ON) is a common manifestation and frequently appears in combination with other MOGAD phenotypes, particularly in young children. Despite permanent structural damage to the retinal nerve fiber layer (RNFL), children often experience complete visual recovery.

AIMS

To analyze the progression and impact of MOGAD on the visual system of pediatric patients independently of the history of ON.

METHODS

This retrospective study included children who met specific criteria: myelin oligodendrocyte glycoprotein (MOG) immunoglobulin G (IgG) seropositivity, acute presentation of MOGAD, and written general consent. Main outcome measures were global peripapillary retinal nerve fiber layer (pRNFL) thickness, and near and distance visual acuity, analyzed using descriptive statistics.

RESULTS

We identified 10 patients with median age of 7.7 years at first event: 7 patients manifested with acute disseminated encephalomyelitis (ADEM) (with ON 5/7, ADEM only 1/7, with transverse myelitis (TM) 1/7), 2 with isolated ON, and 1 patient with neuromyelitis optica spectrum disorder (NMOSD)-like phenotype with ON. Among ON patients, 5/8 were affected bilaterally, with 3 initially diagnosed with unilateral ON but experiencing subsequent involvement of the fellow eye. None of the patients without previous ON showed a deterioration of visual acuity and, if evaluated, a reduction of the pRNFL.

CONCLUSION

Most pediatric MOGAD-ON patients in our cohort presented with acute vison loss and optic disc edema. All patients achieved complete visual recovery, independent of number of relapses or initial visual loss. The pRNFL thickness decreased for several months and stabilized at reduced levels after 12 months in the absence of further relapses. MOGAD may not have subclinical/'silent' effects on the visual system, as visual acuity and pRNFL were not affected in patients without ON.

Novel CRYGC Mutation in Conserved Ultraviolet-Protective Tryptophan (p.Trp131Arg) Is Linked to Autosomal Dominant Congenital Cataract

Congenital cataract (CC), the most prevalent cause of childhood blindness and amblyopia, necessitates prompt and precise genetic diagnosis. The objective of this study is to identify the underlying genetic cause in a Swiss patient with isolated CC. Whole exome sequencing (WES) and copy number variation (CNV) analysis were conducted for variant identification in a patient born with a total binocular CC without a family history of CC. Sanger Sequencing was used to confirm the variant and segregation analysis was used to screen the non-affected parents. The first de novo missense mutation at c.391T>C was identified in exon 3 of CRYGC on chromosome 2 causing the substitution of a highly conserved Tryptophan to an Arginine located at p.Trp131Arg. Previous studies exhibit significant changes in the tertiary structure of the crystallin family in the following variant locus, making CRYGC prone to aggregation aggravated by photodamage resulting in cataract. The variant can be classified as pathogenic according to the American College of Medical Genetics and Genomics (ACMG) criteria (PP3 + PM1 + PM2 + PS2; scoring 10 points). The identification of this novel variant expands the existing knowledge on the range of variants found in the CRYGC gene and contributes to a better comprehension of cataract heterogeneity.

Functional and Morphological Characteristics of the Retina of Patients with Drusen-like Deposits and Systemic Lupus Erythematosus Treated with Hydroxychloroquine: A Retrospective Study

PURPOSE

To evaluate the impact of drusen-like deposits (DLD) on retinal layer integrity and retinal function by optical coherence tomography (OCT) and multifocal electroretinography (mfERG) in patients with systemic lupus erythematosus (SLE).

METHODS

We identified 66 eyes of 33 SLE patients treated with hydroxychloroquine (HCQ) that were categorized into two groups according to whether DLDs were present (34 eyes, Group One) or absent (32 eyes, Group Two). The groups were matched for age, sex, HCQ treatment duration, daily, and cumulative dosage. OCT (retinal layer thicknesses, central retinal thickness, CRT) and mfERG concentric ring analysis were analyzed and compared.

RESULTS

CRT was significantly thicker in Group One compared to Group Two (273.21 ± 3.96 vs. 254.5 ± 7.62) (p = 0.023). Group One also demonstrated an overall thicker retinal pigment epithelium compared to Group Two; however, the other outer retinal layers, outer nuclear layer, and photoreceptor layer were found to be significantly thinner in Group One compared to Group Two. We found no differences in mfERG parameters between the two groups.

CONCLUSIONS

DLDs in SLE patients lead to abnormal central retinal layer thickness, which has no measurable impact on cone-mediated retinal function assessed by mfERG.

Functional Analysis of a Novel, Non-Canonical RPGR Splice Variant Causing X-Linked Retinitis Pigmentosa

X-linked retinitis pigmentosa (XLRP) caused by mutations in the RPGR gene is one of the most severe forms of RP due to its early onset and intractable progression. Most cases have been associated with genetic variants within the purine-rich exon ORF15 region of this gene. RPGR retinal gene therapy is currently being investigated in several clinical trials. Therefore, it is crucial to report and functionally characterize (all novel) potentially pathogenic DNA sequence variants. Whole-exome sequencing (WES) was performed for the index patient. The splicing effects of a non-canonical splice variant were tested on cDNA from whole blood and a minigene assay. WES revealed a rare, non-canonical splice site variant predicted to disrupt the wildtype splice acceptor and create a novel acceptor site 8 nucleotides upstream of RPGR exon 12. Reverse-transcription PCR analyses confirmed the disruption of the correct splicing pattern, leading to the insertion of eight additional nucleotides in the variant transcript. Transcript analyses with minigene assays and cDNA from peripheral blood are useful tools for the characterization of splicing defects due to variants in the RPGR and may increase the diagnostic yield in RP. The functional analysis of non-canonical splice variants is required to classify those variants as pathogenic according to the ACMG's criteria.

Homozygosity for a Novel DOCK7 Variant Due to Segmental Uniparental Isodisomy of Chromosome 1 Associated with Early Infantile Epileptic Encephalopathy (EIEE) and Cortical Visual Impairment

Early infantile epileptic encephalopathy (EIEE) is a severe neurologic and neurodevelopmental disease that manifests in the first year of life. It shows a high degree of genetic heterogeneity, but the genetic origin is only identified in half of the cases. We report the case of a female child initially diagnosed with Leber congenital amaurosis (LCA), an early-onset retinal dystrophy due to photoreceptor cell degeneration in the retina. The first examination at 9 months of age revealed no reaction to light or objects and showed wandering eye movements. Ophthalmological examination did not show any ocular abnormalities. The patient displayed mildly dysmorphic features and a global developmental delay. Brain MRI demonstrated pontine hypo-/dysplasia. The patient developed myoclonic epileptic seizures and epileptic spasms with focal and generalized epileptiform discharges on electroencephalogram (EEG) at the age of 16 months. Genetic screening for a potentially pathogenic DNA sequence variant by whole-exome sequencing (WES) revealed a novel, conserved, homozygous frameshift variant (c.5391delA, p.(Ala1798LeufsTer59)) in exon 42 of the DOCK7 gene (NM_001271999.1). Further analysis by SNP array (Karyomapping) showed loss of heterozygosity (LOH) in four segments of chromosome 1. WES data of the parents and the index patient (trio analysis) demonstrated that chromosome 1 was exclusively inherited from the mother. Four LOH segments of chromosome 1 alternately showed isodisomy (UPiD) and heterodisomy (UPhD). In WES data, the father was a noncarrier, and the mother was heterozygous for this DOCK7 variant. The DOCK7 gene is located in 1p31.3, a region situated in one of the four isodisomic segments of chromosome 1, explaining the homozygosity seen in the affected child. Finally, Sanger sequencing confirmed maternal UPiD for the DOCK7 variant. Homozygous or compound heterozygous pathogenic variants in the DOCK7 (dedicator of cytokinesis 7) gene are associated with autosomal recessive, early infantile epileptic encephalopathy 23 (EIEE23; OMIM #615,859), a rare and heterogeneous group of neurodevelopmental disorders diagnosed during early childhood. To our knowledge, this is the first report of segmental uniparental iso- and heterodisomy of chromosome 1, leading to homozygosity of the DOCK7 frameshift variant in the affected patient.

[Non-Organic Visual Loss in Children and Teenagers]

BACKGROUND

Functional visual disorders in children and adolescents are an important but challenging differential diagnosis. What is characteristic is the discrepancy between the symptomatology and the objective findings. The aim of our work was to analyse the data of those patients who were cared for at our clinic with the diagnosis "functional visual disorders".

PATIENTS AND METHODS

A retrospective data analysis was performed: age < 18 years, with diagnosis "functional visual disorder" 2011 to 2020. Historical and clinical data were extracted from the patient's file. In addition, parents or patients were contacted using a questionnaire about current symptoms. The study was approved by the cantonal ethics committee of Zürich (KEK Nr. 2020-01268).

RESULTS

A total of 92 patients were identified, and analysis could be performed in 53% (49/92; 32 female, 17 male) with available consent. The age ranged from 3 to 18 years (median 10.5 years) with a follow-up of 1 to 58 months (median 7 months). The most common symptoms were bilateral visual loss (55%) and/or blurred vision (18%) with headache (35%), motility pain (14%), photophobia (4%), dizziness (4%), and malaise (2%). A reduction in distant (22/49 bilateral, 9/49 unilateral) and near (24/49 bilateral, 3/49 unilateral) visual acuity was documented. Subjective visual acuity reduction was no longer detectable in 20% of patients at testing. Psychological distress was documented in 13/49 patients. Moisturising eye drops (18/49), eyeglass prescription (15/49), or no therapy (20/49) was recommended. Subjective and/or objective improvement was documented at follow-up in 49% (24/49). The questionnaire was answered in 86%: no complete remission of visual symptoms (10/42), remission within 1 week (14/41), 1 month (3/41), 2 - 6 months (8/41), 1 year (6/41). There was no correlation between duration of visual symptoms and age at onset or gender. The consultation at our clinic was reported as "supportive and helpful" in 31/42 patients.

CONCLUSION

Despite a low incidence during the history, the psychosocial and psychological component should not be neglected.

The "Eyelet Sign" as an MRI Clue for Inflammatory Brown Syndrome

BACKGROUND

Brown syndrome is characterized by a restrictive elevation deficit of the affected eye in adduction. Besides the well-known congenital form, different acquired etiologies including inflammation, trauma, and surgery may prevent the superior oblique (SO) tendon from gliding freely through the trochlea on attempted upgaze. We present MRI findings in pediatric and adult patients with inflammatory acquired Brown syndrome.

METHODS

Retrospective review of clinical and MRI findings of 6 patients (4 children: median age 8.4 years [range 6.1-8.7]; 2 adults: age 46.4 and 51.1 years). Median follow-up was 23 months (range 1-52).

RESULTS

In all 6 patients, orbital MRI demonstrated inflammatory changes of the SO tendon-trochlea complex. A striking feature was circumferential contrast enhancement of the trochlea with central sparing where the tendon passes, reminiscent of an eyelet. In all cases, the motility restriction improved either spontaneously or with systemic anti-inflammatory treatment. Although both adult patients had a history of known seronegative spondyloarthritis, there was no associated systemic condition in the children in our series.

CONCLUSIONS

Both in children and in adults, MRI can provide evidence of inflammatory changes located at the trochlea-tendon complex in acquired Brown syndrome here referred to as the "eyelet sign," which may be helpful in confirming the clinical diagnosis and guide appropriate treatment.

OUP accepted manuscript

Recessive mutations in the CTNS gene encoding the lysosomal transporter cystinosin cause cystinosis, a lysosomal storage disease leading to kidney failure and multisystem manifestations. A Ctns knockout mouse model recapitulates features of cystinosis, but the delayed onset of kidney manifestations, phenotype variability and strain effects limit its use for mechanistic and drug development studies. To provide a better model for cystinosis, we generated a Ctns knockout rat model using CRISPR/Cas9 technology. The Ctns^−/− rats display progressive cystine accumulation and crystal formation in multiple tissues including kidney, liver and thyroid. They show an early onset and progressive loss of urinary solutes, indicating generalized proximal tubule dysfunction, with development of typical swan-neck lesions, tubulointerstitial fibrosis and kidney failure, and decreased survival. The Ctns^−/− rats also present crystals in the cornea, and bone and liver defects, as observed in patients. Mechanistically, the loss of cystinosin induces a phenotype switch associating abnormal proliferation and dedifferentiation, loss of apical receptors and transporters, and defective lysosomal activity and autophagy in the cells. Primary cultures of proximal tubule cells derived from the Ctns^−/− rat kidneys confirmed the key changes caused by cystine overload, including reduced endocytic uptake, increased proliferation and defective lysosomal dynamics and autophagy. The novel Ctns^−/− rat model and derived proximal tubule cell system provide invaluable tools to investigate the pathogenesis of cystinosis and to accelerate drug discovery.

A three-year longitudinal study of retinal function and structure in patients with multiple sclerosis

Background

Researchers have in recent years begun to investigate ophthalmological manifestations of multiple sclerosis (MS) other than optic neuritis (ON), and it is now clear that changes to retinal function (measured using the electroretinogram, ERG) and structure (measured using optical coherence tomography, OCT) are found in MS patients irrespective of prior ON episodes. ERG results are consistent with dysfunctional bipolar cells, as in other autoimmune diseases. To date, studies have presented only cross-sectional data regarding ERG and OCT. We, therefore, studied the longitudinal course of ERG and OCT in patients with MS, as well as the effect of disability changes and non-ON clinical relapses on these functional and structural measures.

Methods

MS patients (n = 23) participating in an ongoing longitudinal observational study were invited to take part in a 3-year ophthalmological substudy. ERG and OCT were performed, and measures of MS-related disability and relapse history were obtained. Study visits were repeated annually. ERG peak times, rod b-wave amplitude, mixed rod/cone and cone b-/a-wave amplitude ratios, thickness of the peripapillary retinal nerve fibre layer, and volumes of the segmented retinal layers/complexes were analysed. Using generalised estimating equation models adjusted for age, ON, and MS treatment status, we assessed changes to ERG and OCT over the study duration, the effect of changes in disability and recent non-ON MS relapses on ERG and OCT, and the effect of selected OCT parameters on corresponding ERG parameters.

Results

At the group level, small fluctuations of several ERG peak times were recorded, with OCT values remaining stable. Increased disability between visits was associated with significant prolongation of mixed rod-cone ERG b-wave peak times. No evidence of associations between OCT and ERG parameters was observed.

Conclusions

Retinal bipolar cell function may be affected by changes in disability in patients with MS; however, recent non-ON MS clinical relapses appear not to affect ERG or OCT results. As ERG changes in MS patients over 3 years are likely to be small and of uncertain clinical relevance, longitudinal studies of retinal function in MS should be planned over an extended period.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10633-021-09855-7.

Genetic Analysis in a Swiss Cohort of Bilateral Congenital Cataract

Importance

Identification of geographic population-based differences in genotype and phenotype heterogeneity are important for targeted and patient-specific diagnosis and treatment, counseling, and screening strategies.

Objective

To report disease-causing variants and their detailed phenotype in patients with bilateral congenital cataract from a single center in Switzerland and thereby draw a genetic map and perform a genotype-phenotype comparison of this cohort.

Design, Setting, and Participants

This clinical and molecular-genetic cohort study took place through the collaboration of the Department of Ophthalmology at the University Hospital Zurich and the Institute of Medical Molecular Genetics, University of Zurich, Schlieren, Switzerland. Thirty-seven patients from 25 families with different types of bilateral congenital cataract were included. All participating family members received a comprehensive eye examination. Whole exome sequencing was performed in the index patients, followed by a filtering process to detect possible disease-associated variants in genes previously described in association with congenital cataract. Probable disease-causing variants were confirmed by Sanger sequencing in available family members. All data were collected from January 2018 to June 2020, and the molecular-genetic analyses were performed from January 2019 to July 2020.

Main Outcomes and Measures

Identification of the underlying genetic causes of bilateral congenital cataract, including novel disease-causing variants and phenotype correlation.

Results

Among the 37 patients (18 [49%] male and 19 [51%] female; mean [SD] age, 17.3 [15.9] years) from 25 families, pathogenic variants were detected in 20 families (80% detection rate), which included 13 novel variants in the following genes: BCOR, COL4A1, CRYBA2, CRYBB2, CRYGC, CRYGS, GJA3, MAF, NHS, and WFS1. Putative disease-causing variants were identified in 14 of 20 families (70%) as isolated cases and in 6 of 20 families (30%) with syndromic cases. A recessive variant in the CRYBB2 gene in a consanguineous family with 2 affected siblings showing a nuclear and sutural cataract was reported in contrast to previously published reports. In addition, the effect on splicing in a minigene assay of a novel splice site variant in the NHS gene (c.[719-2A>G]) supported the pathogenicity of this variant.

Conclusions and Relevance

This study emphasizes the importance of genetic testing of congenital cataracts. Known dominant genes need to be considered for recessive inheritance patterns. Syndromic types of cataract may be underdiagnosed in patients with mild systemic features.

Confirmation of Ogden syndrome as an X-linked recessive fatal disorder due to a recurrent NAA10 variant and review of the literature

Ogden syndrome is a rare lethal X‐linked recessive disorder caused by a recurrent missense variant (Ser37Pro) in the NAA10 gene, encoding the catalytic subunit of the N‐terminal acetyltransferase A complex (NatA). So far eight boys of two different families have been described in the literature, all presenting the distinctive and recognizable phenotype, which includes mostly postnatal growth retardation, global severe developmental delay, characteristic craniofacial features, and structural cardiac anomalies and/or arrhythmias. Here, we report the ninth case of Ogden syndrome with an independent recurrence of the Ser37Pro variant. We were able to follow the clinical course of the affected boy and delineate the evolving phenotype from his birth until his unfortunate death at 7 months. We could confirm the associated phenotype as well as the natural history of this severe disease. By describing new presenting features, we are further expanding the clinical spectrum associated with Ogden syndrome and review other phenotypes associated with NAA10 variants.

[Acute Acquired Comitant Esotropia Type 2 - A Retrospective Analysis]

BACKGROUND

Acute acquired comitant esotropia (AACE) is an uncommon form of strabismus. The main characteristics of AACE Type 2 in childhood are: acute onset of strabismus around 3 years of age, large and comitant angle of strabismus, absence of accommodative component, hyperopia of not more than 3 dpt, and measurable stereopsis. Strabismus surgery is urgently indicated in AACE Type 2 in order to avoid maldevelopment or loss of stereopsis. Therefore, in order to better describe the characteristics of AACE Type 2, we performed a retrospective analysis of patients previously seen in our clinic.

PATIENTS AND METHODS

Retrospective analysis of data from patients who underwent strabismus surgery between October 2011 and September 2019 due to suspected AACE Type 2 could be confirmed during postoperative visits by evaluating ocular alignment and stereopsis at our hospital. Analysed data included: age and symptoms at first visit, visual acuity, refractive status, correction by glasses, age at surgery, period of time between first symptoms and surgery, surgical procedure, stereopsis and angle of strabismus (before surgery and 1 day, 3 months, and 12 months after surgery). Ethical approval was obtained from the Cantonal Ethics Committee of Zurich.

RESULTS

18 patients (12 male, 6 female) with mean hyperopia of 1.4 ± 0.6 dpt were identified as meeting the inclusion criteria during the defined time period. Amblyopia was present at first assessment in two patients. Strabismus surgery was performed at 2.0 to 11.1 years of age and between 0.4 and 24.6 months after onset of symptoms. Surgery was performed within 6 months after onset of symptoms in 12/18 children. Before surgery, angle of strabismus at near was measured as 38 ± 10 prism diopters (PD) and was reduced after surgery to 3 ± 3 PD at 3 months and 2 ± 2 PD at 12 months. Stereopsis was confirmed in 5/18 patients one day after surgery and in 18/18 patients 12 months after surgery.

CONCLUSION

Our analysis showed that our patients with diagnosis of AACE Type 2 had mild hyperopia and large comitant non-accommodative esotropia; prognosis for recovery of stereopsis is excellent. Preoperative amblyopia does not exclude the diagnosis of AACE Type 2. Therapeutic intervention is advisable within a short period of time after first symptoms and the diagnosis of AACE Type 2.

Long-Range PCR-Based NGS Applications to Diagnose Mendelian Retinal Diseases

The purpose of this study was to develop a flexible, cost-efficient, next-generation sequencing (NGS) protocol for genetic testing. Long-range polymerase chain reaction (PCR) amplicons of up to 20 kb in size were designed to amplify entire genomic regions for a panel (n = 35) of inherited retinal disease (IRD)-associated loci. Amplicons were pooled and sequenced by NGS. The analysis was applied to 227 probands diagnosed with IRD: (A) 108 previously molecularly diagnosed, (B) 94 without previous genetic testing, and (C) 25 undiagnosed after whole-exome sequencing (WES). The method was validated with 100% sensitivity on cohort A. Long-range PCR-based sequencing revealed likely causative variant(s) in 51% and 24% of proband from cohorts B and C, respectively. Breakpoints of 3 copy number variants (CNVs) could be characterized. Long-range PCR libraries spike-in extended coverage of WES. Read phasing confirmed compound heterozygosity in 5 probands. The proposed sequencing protocol provided deep coverage of the entire gene, including intronic and promoter regions. Our method can be used (i) as a first-tier assay to reduce genetic testing costs, (ii) to elucidate missing heritability cases, (iii) to characterize breakpoints of CNVs at nucleotide resolution, (iv) to extend WES data to non-coding regions by spiking-in long-range PCR libraries, and (v) to help with phasing of candidate variants.

Whole Exome Sequencing in Coloboma/Microphthalmia: Identification of Novel and Recurrent Variants in Seven Genes

Coloboma and microphthalmia (C/M) are related congenital eye malformations, which can cause significant visual impairment. Molecular diagnosis is challenging as the genes associated to date with C/M account for only a small percentage of cases. Overall, the genetic cause remains unknown in up to 80% of patients. High throughput DNA sequencing technologies, including whole-exome sequencing (WES), are therefore a useful and efficient tool for genetic screening and identification of new mutations and novel genes in C/M. In this study, we analyzed the DNA of 19 patients with C/M from 15 unrelated families using singleton WES and data analysis for 307 genes of interest. We identified seven novel and one recurrent potentially disease-causing variants in CRIM1, CHD7, FAT1, PTCH1, PUF60, BRPF1, and TGFB2 in 47% of our families, three of which occurred de novo. The detection rate in patients with ocular and extraocular manifestations (67%) was higher than in patients with an isolated ocular phenotype (46%). Our study highlights the significant genetic heterogeneity in C/M cohorts and emphasizes the diagnostic power of WES for the screening of patients and families with C/M.

Atonal homolog 7 (ATOH7) loss-of-function mutations in predominant bilateral optic nerve hypoplasia

Optic nerve hypoplasia (ONH) is a congenital optic nerve abnormality caused by underdevelopment of retinal ganglion cells (RGCs). Despite being a rare disease, ONH is the most common optic disk anomaly in ophthalmological practice. So far, mutations in several genes have been identified as causative; however, many cases of ONH remain without a molecular explanation. The early transcription factor atonal basic-helix-loop-helix (bHLH) transcription factor 7 (ATOH7) is expressed in retinal progenitor cells and has a crucial role in RGC development. Previous studies have identified several mutations in the ATOH7 locus in cases of eye developmental diseases such as non-syndromic congenital retinal non-attachment and persistent hyperplasia of the primary vitreous. Here we present two siblings with a phenotype predominated by bilateral ONH, with additional features of foveal hypoplasia and distinct vascular abnormalities, where whole-exome sequencing identified two compound heterozygous missense mutations affecting a conserved amino acid residue within the bHLH domain of ATOH7 (NM_145178.3:c.175G>A; p.(Ala59Thr) and c.176C>T; p.(Ala59Val)). ATOH7 expression constructs with patient single nucleotide variants were cloned for functional characterization. Protein analyses revealed decreased protein amounts and significantly enhanced degradation in the presence of E47, a putative bHLH dimerization partner. Protein interaction assays revealed decreased heterodimerization and DNA-binding of ATOH7 variants, resulting in total loss of transcriptional activation of luciferase reporter gene expression. These findings strongly support pathogenicity of the two ATOH7 mutations, one of which is novel. Additionally, this report highlights the possible impact of altered ATOH7 dimerization on protein stability and function.

Exome Sequencing in a Swiss Childhood Glaucoma Cohort Reveals CYP1B1 and FOXC1 Variants as Most Frequent Causes

Purpose

The aim of this study was to investigate the molecular basis of childhood glaucoma in Switzerland to recommend future targeted genetic analysis in the Swiss population.

Methods

Whole-exome sequencing and copy number variation (CNV) analysis was performed in a Swiss cohort of 18 patients from 14 unrelated families. Identified variants were validated by Sanger sequencing and multiplex ligation-dependent probe amplification. Breakpoints of structural variants were determined by a microarray. A minigene assay was conducted for functional analysis of a splice site variant.

Results

A diagnosis of primary congenital glaucoma was made in 14 patients, of which six (43%) harbored pathogenic variants in CYP1B1, one (7%) a frameshift variant in FOXC1, and seven (50%) remained without a genetic diagnosis. Three patients were diagnosed with glaucoma associated with nonacquired ocular anomalies, of which two patients with mild ocular features of Axenfeld-Rieger syndrome harbored a FOXC1 duplication plus an additional FOXC1 missense variant, and one patient with a Barkan membrane remained without genetic diagnosis. A diagnosis of juvenile open-angle glaucoma was made in one patient, and genetic analysis revealed a FOXC1 duplication.

Conclusions

Sequencing of CYP1B1 and FOXC1, as well as analysis of CNVs in FOXC1, should be performed before extended gene panel sequencing.

Translational Relevance

The identification of the molecular cause of childhood glaucoma is a prerequisite for genetic counseling and personalized care for patients and families.

Genotype-Phenotype Analysis of a Novel Recessive and a Recurrent Dominant SNRNP200 Variant Causing Retinitis Pigmentosa

Purpose

To compare phenotype variability in retinitis pigmentosa patients with recessive and dominant mutations in the SNRNP200 gene.

Methods

In a retrospective study, patients of two unrelated families were identified: family A, five patients aged 36 to 77 years; family B, one patient aged 9 years and his asymptomatic parents and sister. All patients received a comprehensive eye examination with a detailed retinal functional and morphologic assessment. Genetic testing was performed by whole exome sequencing (WES) in the index patient from each family. Genes described to be involved in eye diseases (n > 450) were screened for rare variants and segregation analysis was performed.

Results

A known heterozygous missense variant (c.3260C>T, p.(Ser1087Leu)) in the SNRNP200 gene was identified in the index patient of family A while a novel homozygous missense mutation (c.1634G>A, p.(Arg545His)) was found in the index patient of family B. Nyctalopia and photophobia were reported by 6/6 and 2/6 patients, respectively. The phenotype associated with the dominant mutation was characterized by variable disease onset (early childhood to the sixth decade of life), disease severity (visual acuity of 20/20-20/200 in the seventh to eighth decade), and advanced rod-cone dysfunction. Characteristics of recessive disease included distinct fundus changes of dot-like hypopigmentation together with retinal atrophy and severe rod-cone dysfunction.

Conclusions

The phenotype characteristics in autosomal dominant and recessive SNRNP200 mutations show distinct features, with earlier severe disease in the recessive case and a variable disease expression in the dominant inheritance pattern.

Longstanding diplopia after ethmoidal artery ligation for epistaxis

PURPOSE

In the rare case of intractable, posterior, non-sphenopalatine artery epistaxis, ligation of ethmoidal arteries using an external approach like a Lynch-type incision is required. Orbital complications, especially extra-ocular motility disorders with diplopia, are known, but in the literature rarely described. Our aim was to analyse the complication type, rate, and outcome of ethmoidal artery ligation for epistaxis.

MATERIALS AND METHODS

Data between 2012 and 2017 of patients treated with ethmoidal artery ligation were analysed retrospectively and through a telephone interview using a non-standardized questionnaire.

RESULTS

Data of 18 patients (m/f = 3/15) aged 53-83 years were reviewed. Epistaxis recurred in only one patient after 1 month. Five patients (28%) suffered from diplopia shortly after surgery. Motility analysis revealed full recovery with free motility in four out of five reported cases after 4-8 months, one patient still reports intermittent mild diplopia more than 1 year postoperatively.

CONCLUSION

In patients with intractable, non-sphenopalatine artery epistaxis, anterior ethmoidal artery ligation was highly effective. Diplopia, however, occurred in one-third of our patient group. Information about motility restriction with longer standing diplopia are mandatory when consenting patients for ligation of ethmoidal arteries. Special care needs to be taken during dissection in the region of the trochlea and superior oblique muscle.

LEVEL OF EVIDENCE

Case Series, level 4.

[Ocular Phenotype and Complications in Patients with Tuberous Sclerosis Complex (TSC)]

BACKGROUND

Evaluation and comparison of the ocular phenotype in patients diagnosed with tuberous sclerosis complex (TSC). Analysis of ocular complications during follow-up.

PATIENTS AND METHODS

A retrospective chart review was performed of patients with TSC who had received an ocular examination at the eye clinic of the University Hospital Zurich. Data were analysed on visual acuity (VA) assessment, refraction, anterior and posterior eye examination including the distinction of different types of hamartomas and, when available, visual fields. The study was approved by the Cantonal Ethics Committee of Zurich.

RESULTS

A total of 30 patients who were diagnosed with TSC (19 female, 11 male) were included in the analysis. The age at first examination varied from 7 months to 44 years (mean 13.3 years, standard deviation 11.31). 17/30 patients received a follow-up examination between 4 months and 19 years (mean 4.3 years, standard deviation 5.24). Data of VA were available in 26/30 patients, of whom 22 had normal vision in both eyes. The causes of reduced VA in the 4 patients were: complications of a subependymal giant cell astrocytoma followed by a bilateral optic nerve atrophy; vigabatrin-associated optic atrophy; anterior segment dysgenesis; unilateral amblyopia. Adequate VA testing was not possible in 4 patients because of intellectual disabilities. Retinal hamartomas were described in 15/30 patients: 8 unilateral, 7 bilateral. The flat hamartoma type was described in 10/15 patients, the multinodular type in 6/15 patients.

CONCLUSIONS

The ocular phenotype in our patient cohort shows similar TSC involvement to that described in the literature. Patients diagnosed with TSC require regular ophthalmic examinations to diagnose secondary ocular complications, such as papilloedema, severe vision loss or visual field constriction.

Prediction of ROP Treatment and Evaluation of Screening Criteria in VLBW Infants-a Population Based Analysis

BACKGROUND

The incidence of retinopathy of prematurity (ROP) and ROP screening criteria differ between countries. We assessed whether ROP screening could be reduced based on the local ROP incidence.

METHODS

Observational cohort study of infants born in Switzerland between 2006 and 2015 <32 0/7 weeks. Chronological and postmenstrual ages at ROP treatment were analyzed. A model to identify ROP treatment on patients born between 2006 and 2012 (training set) was developed and tested on patients born between 2013 and 2015 (validation set).

RESULTS

Of 7817 live-born infants, 1098 died within the first 5 weeks of life. The remaining 6719 infants were included into analysis. All patients requiring ROP treatment would have been identified if screening had been performed before reaching 60 days of life or 37 3/7 weeks postmenstrual age, whichever came first. The training and validation sets included 4522 and 2197 preterm infants encompassing 56 and 20 patients receiving ROP treatment, respectively. All patients would have required screening to reach 100% sensitivity. To reach a sensitivity of 95.0% and a specificity of 87.6%, we predicted a reduction in 13.2% of patients requiring screening (c-statistic = 0.916).

CONCLUSIONS

A substantial reduction of infants requiring screening seems possible, but necessitates prospective testing of new screening criteria.

Outer Retinal Dysfunction in the Absence of Structural Abnormalities in Multiple Sclerosis

Purpose

Recent evidence suggests structural changes distal to the inner retina in multiple sclerosis (MS) patients. The functional correlates of these proposed structural abnormalities remain unclear. We investigated outer retinal function and structure in MS patients, and quantified to what extent outer retinal structure influenced function in these patients.

Methods

Outer retinal function was assessed using the full-field and multifocal electroretinogram (ERG/MF-ERG), whereas retinal structure was assessed using spectral-domain optical coherence tomography (OCT). Results were compared with preexisting normative data. The relationships between electrophysiology parameters and the OCT values corresponding to the proposed cellular origins of the ERG and MF-ERG were analyzed.

Results

Most electrophysiological responses were delayed in MS patients, independently of optic neuritis (ON). Inner retinal thickness and volumes were reduced, and inner nuclear layer volume marginally increased, in eyes with previous ON; all other OCT parameters were normal. OCT results correlated with ERG amplitudes, but not with ERG peak times or any MF-ERG parameters.

Conclusions

We recorded outer retinal dysfunction without detectable abnormalities of the corresponding retinal layers in MS patients, not ascribable to retrograde degeneration following ON. The findings complement a growing body of literature reporting primary retinal abnormalities distal to the ganglion cell-inner plexiform layer complex in MS patients, with our data suggesting that this may be a more widespread phenomenon than previously thought. ERG may be of more utility in detecting retinal dysfunction in MS patients than MF-ERG. Analysis of peak times, rather than response amplitudes, is recommended.

Incidence of retinopathy of prematurity (ROP) and ROP treatment in Switzerland 2006-2015: a population-based analysis

BACKGROUND

Retinopathy of prematurity (ROP) is a severe complication of preterm birth and can lead to severe visual impairment or even blindness if untreated. The incidence of ROP requiring treatment is increasing in some developed countries in conjunction with higher survival rates at the lower end of gestational age (GA).

MATERIAL AND METHODS

The incidence of ROP and severe ROP (sROP) requiring treatment in Switzerland was analysed using the SwissNeoNet registry. We conducted a retrospective cohort analysis of very preterm infants with a GA below 32 weeks who were born between 2006 and 2015 in Switzerland. Patient characteristics were stratified according to GA.

RESULTS

9.3% and 1.8% of very preterm infants in Switzerland developed ROP of any stage and sROP, respectively. The incidence of ROP treatment was 1.2%. Patients with 24 and 25 weeks GA had the highest proportion of ROP treatment at 14.5% and 7.3%, respectively, whereas the proportion of treated infants at or above a GA of 29 weeks was 0.06%. Similarly, the risk of sROP declined strongly with increasing GA. During the observation period of 10 years, the incidence of ROP treatment ranged between 0.8% and 2.0%. Incidences of sROP or ROP treatment did not increase over time.

CONCLUSION

The incidence of ROP treatment in Switzerland is low and was stable over the analysed period. The low incidence of sROP in patients with a GA of 29 weeks or more leaves room for a redefinition of ROP screening criteria.

Spontaneous Nystagmus in the Dark in an Infantile Nystagmus Patient May Represent Negative Optokinetic Afternystagmus

Abnormal projection of the optic nerves to the wrong cerebral hemisphere transforms the optokinetic system from its usual negative feedback loop to a positive feedback loop with characteristic ocular motor instabilities including directional reversal of the optokinetic nystagmus (OKN) and spontaneous nystagmus, which are common features of infantile nystagmus syndrome (INS). Visual input plays a critical role in INS linked to an underlying optic nerve misprojection such as that often seen in albinism. However, spontaneous nystagmus often continues in darkness, making the visual, sensory-driven etiology questionable. We propose that sensorimotor adaptation during the constant nystagmus of patients in the light could account for continuing nystagmus in the dark. The OKN is a stereotyped reflexive eye movement in response to motion in the surround and serves to stabilize the visual image on the retina, allowing high resolution vision. Robust negative optokinetic afternystagmus (negative OKAN), referring to the continuous nystagmus in the dark with opposite beating direction of the preceding OKN, has been identified in various non-foveated animals. In humans, a robust afternystagmus in the same direction as previous smooth-pursuit movements (the eye's continuous tracking and foveation of a moving target) induced by visual stimuli has been known to commonly mask negative OKAN. Some INS patients are often associated with ocular hypopigmentation, foveal hypoplasia, and compromised smooth pursuit. We identified an INS case with negative OKAN in the dark, in contrast to the positive afternystagmus in healthy subjects. We hypothesize that spontaneous nystagmus in the dark in INS patients may be attributable to sensory adaptation in the optokinetic system after a sustained period of spontaneous nystagmus with directional visual input in light.

Infantile hemangiomas with conjunctival involvement: An underreported occurrence

BACKGROUND/OBJECTIVES

Infantile hemangiomas (IHs) involving the conjunctiva are only anecdotally reported in the literature and little is known about their clinical course. In a retrospective case series we aimed to better delineate the clinical presentation, complications, and response to treatment of this uncommon subtype of IH. A classification of conjunctival IH is proposed.

METHODS

Medical charts at three academic pediatric dermatology institutions were retrospectively analyzed. Data were collected on the clinical characteristics, ophthalmologic findings, treatments, and outcomes of 22 individuals with conjunctival IH.

RESULTS

Growth characteristics of conjunctival IH closely mirrored those of their cutaneous counterparts. Ophthalmologic abnormalities were associated with the IH in six individuals (27%); in three, they were considered severe. Seventeen subjects (77%) required treatment, most commonly because of risk of ocular compromise. All treated individuals responded favorably to topical timolol or systemic propranolol.

CONCLUSION

Conjunctival IH have clinical characteristics similar to those of cutaneous IH and respond readily to beta-blocker treatment. Ocular complications may occur in a minority of individuals receiving treatment.

Unusual retinopathy in a child with severe combined immune deficiency

We describe a case of an infant diagnosed with severe combined immune deficiency (Adenosine Deaminase (ADA), SCID) with severe retinopathy and associated low vision in both eyes at first examination. An extensive infectious work up revealed an enterovirus infection, which suggested an early infectious and severe retinopathy. Genetic causes of congenital retinitis pigmentosa/ Leber's congenital amaurosis could be excluded by whole exome sequencing.

Senescent Changes and Topography of the Dark-Adapted Multifocal Electroretinogram

Purpose

To investigate the topographic changes of the dark-adapted multifocal electroretinogram (mfERG) across adulthood in the central retina and compare the topography between macular versus extramacular, nasal versus temporal, and inferior versus superior retinal areas.

Methods

Sixty-five subjects (18–88 years) received a comprehensive dilated eye examination to ensure the health of their retina and were tested with a dark-adapted mfERG protocol using a 61-hexagon pattern. The lens absorption of each subject was also estimated using a heterochromatic flicker photometry (HFP) paradigm.

Results

The response amplitude and latency of the dark-adapted mfERG showed a significant change with age, which was best described with a linear model. All the retinal areas examined demonstrated similar aging effects. The extramacular and temporal retina showed higher response amplitude and faster response latency when compared with the macular and nasal retinae, respectively. No difference was found in response amplitude and latency between the inferior and superior retina. The HFP results also showed a significant correlation with age, consistent with senescent increases in short wavelength absorption by the crystalline lens. However, the change in lens absorption did not exceed the magnitude of the change in response amplitude and latency.

Discussion

Our results indicate that there is a decline in dark-adapted retinal activity as measured with the mfERG. These aging processes affect rods and rod-bipolar cells. Their decrease in response can be attributed to both optical and neural factors.

Next generation sequencing based identification of disease-associated mutations in Swiss patients with retinal dystrophies

Inherited monogenic diseases of the retina and vitreous affect approximately 1 in 2000 individuals. They are characterized by tremendous genetic heterogeneity and clinical variability involving mutations in approximately 250 genes and more than 20 different clinical phenotypes. Clinical manifestations of retinal dystrophies (RDs) range from mild retinal dysfunctions to severe congenital forms of blindness. A detailed clinical diagnosis and the identification of causative mutations are crucial for genetic counseling of affected patients and their families, for understanding genotype-phenotype correlations and developing therapeutic approaches. Using whole exome sequencing (WES) we have established a reliable and efficient high-throughput analysis pipeline to identify disease-causing mutations. Our data indicate that this approach enables us to genetically diagnose approximately 64% of the patients (n = 58) with variant(s) in known disease-associated genes. We report 20 novel and 26 recurrent variants in genes associated with RDs. We also identified a novel phenotype for mutations in C2orf71 and provide functional evidence for exon skipping due to a splice-site variant identified in FLVCR1. In conclusion, WES can rapidly identify variants in various families affected with different forms of RDs. Our study also expands the clinical and allelic spectrum of genes associated with RDs in the Swiss population.

A secreted WNT-ligand-binding domain of FZD5 generated by a frameshift mutation causes autosomal dominant coloboma

Ocular coloboma is a common eye malformation resulting from incomplete fusion of the optic fissure during development. Coloboma is often associated with microphthalmia and/or contralateral anophthalmia. Coloboma shows extensive locus heterogeneity associated with causative mutations identified in genes encoding developmental transcription factors or components of signaling pathways. We report an ultra-rare, heterozygous frameshift mutation in FZD5 (p.Ala219Glufs*49) that was identified independently in two branches of a large family with autosomal dominant non-syndromic coloboma. FZD5 has a single-coding exon and consequently a transcript with this frameshift variant is not a canonical substrate for nonsense-mediated decay. FZD5 encodes a transmembrane receptor with a conserved extracellular cysteine rich domain for ligand binding. The frameshift mutation results in the production of a truncated protein, which retains the Wingless-type MMTV integration site family member-ligand-binding domain, but lacks the transmembrane domain. The truncated protein was secreted from cells, and behaved as a dominant-negative FZD5 receptor, antagonizing both canonical and non-canonical WNT signaling. Expression of the resultant mutant protein caused coloboma and microphthalmia in zebrafish, and disruption of the apical junction of the retinal neural epithelium in mouse, mimicking the phenotype of Fz5/Fz8 compound conditional knockout mutants. Our studies have revealed a conserved role of Wnt-Frizzled (FZD) signaling in ocular development and directly implicate WNT-FZD signaling both in normal closure of the human optic fissure and pathogenesis of coloboma.

Dental phenotype in Jalili syndrome due to a c.1312 dupC homozygous mutation in the CNNM4 gene

Jalili syndrome denotes a recessively inherited combination of an eye disease (cone-rod dystrophy) and a dental disorder (amelogenesis imperfecta), which is caused by mutations in the CNNM4 gene. Whereas the ophthalmic consequences of these mutations have been studied comprehensively, the dental phenotype has obtained less attention. A defective transport of magnesium ions by the photoreceptors of the retina is assumed to account for the progressive visual impairment. Since magnesium is also incorporated in the mineral of dental hard tissues, we hypothesized that magnesium concentrations in defective enamel resulting from mutations in CNNM4 would be abnormal, if a similar deficiency of magnesium transport also accounted for the amelogenesis imperfecta. Thus, a detailed analysis of the dental hard tissues was performed in two boys of Kosovan origin affected by Jalili syndrome. Retinal dystrophy of the patients was diagnosed by a comprehensive eye examination and full-field electroretinography. A mutational analysis revealed a c.1312 dupC homozygous mutation in CNNM4, a genetic defect which had already been identified in other Kosovan families and putatively results in loss-of-function of the protein. The evaluation of six primary teeth using light and scanning electron microscopy as well as energy-dispersive X-ray spectroscopy showed that dental enamel was thin and deficient in mineral, suggesting a hypoplastic/hypomineralized type of amelogenesis imperfecta. The reduced mineral density of enamel was accompanied by decreased amounts of calcium, but significantly elevated levels of magnesium. In dentin, however, a similar mineral deficiency was associated with reduced magnesium and normal calcium levels. It is concluded that the c.1312 dupC mutation of CNNM4 results in mineralization defects of both enamel and dentin, which are associated with significantly abnormal magnesium concentrations. Thus, we could not disprove the hypothesis that a disrupted magnesium transport is involved in the development of the dental abnormalities observed in Jalili syndrome.

Clinical and mutation analysis of 51 probands with anophthalmia and/or severe microphthalmia from a single center

Clinical evaluation and mutation analysis was performed in 51 consecutive probands with severe eye malformations - anophthalmia and/or severe microphthalmia - seen in a single specialist ophthalmology center. The mutation analysis consisted of bidirectional sequencing of the coding regions of SOX2, OTX2, PAX6 (paired domain), STRA6, BMP4, SMOC1, FOXE3, and RAX, and genome-wide array-based copy number assessment. Fifteen (29.4%) of the 51 probands had likely causative mutations affecting SOX2 (9/51), OTX2 (5/51), and STRA6 (1/51). Of the cases with bilateral anophthalmia, 9/12 (75%) were found to be mutation positive. Three of these mutations were large genomic deletions encompassing SOX2 (one case) or OTX2 (two cases). Familial inheritance of three intragenic, plausibly pathogenic, and heterozygous mutations was observed. An unaffected carrier parent of an affected child with an identified OTX2 mutation confirmed the previously reported nonpenetrance for this disorder. Two families with SOX2 mutations demonstrated a parent and child both with significant but highly variable eye malformations. Heterozygous loss-of-function mutations in SOX2 and OTX2 are the most common genetic pathology associated with severe eye malformations and bi-allelic loss-of-function in STRA6 is confirmed as an emerging cause of nonsyndromal eye malformations.

Bilateral vitreous hemorrhage in a newborn with Stickler syndrome associated with a novel COL2A1 mutation

Bilateral preretinal and vitreous hemorrhages in infants are rare and can present a diagnostic challenge, with nonaccidental trauma included in the differential diagnosis. We present the case of a 4-week-old boy in which a Pierre Robin sequence and a positive family history led to the clinical diagnosis of Stickler syndrome, which was confirmed by the identification of a disease-causing novel deletion of 2 nucleotides in the COL2A1 gene. This early association with Stickler syndrome has not been described previously.