Neuropathy target esterase activity defines phenotypes among PNPLA6 disorders.

Biallelic pathogenic variants in the PNPLA6 gene cause a broad spectrum of disorders leading to gait disturbance, visual impairment, anterior hypopituitarism and hair anomalies. PNPLA6 encodes neuropathy target esterase (NTE), yet the role of NTE dysfunction on affected tissues in the large spectrum of associated disease remains unclear. We present a systematic evidence-based review of a novel cohort of 23 new patients along with 95 reported individuals with PNPLA6 variants that implicate missense variants as a driver of disease pathogenesis. Measuring esterase activity of 46 disease-associated and 20 common variants observed across PNPLA6-associated clinical diagnoses unambiguously reclassified 36 variants as pathogenic and 10 variants as likely pathogenic, establishing a robust functional assay for classifying PNPLA6 variants of unknown significance. Estimating the overall NTE activity of affected individuals revealed a striking inverse relationship between NTE activity and the presence of retinopathy and endocrinopathy. This phenomenon was recaptured in vivo in an allelic mouse series, where a similar NTE threshold for retinopathy exists. Thus, PNPLA6 disorders, previously considered allelic, are a continuous spectrum of pleiotropic phenotypes defined by an NTE genotype:activity:phenotype relationship. This relationship, and the generation of a preclinical animal model, pave the way for therapeutic trials, using NTE as a biomarker.

Human TUBB3 mutations perturb microtubule dynamics, kinesin interactions, and axon guidance.

We report that eight heterozygous missense mutations in TUBB3, encoding the neuron-specific beta-tubulin isotype III, result in a spectrum of human nervous system disorders that we now call the TUBB3 syndromes. Each mutation causes the ocular motility disorder CFEOM3, whereas some also result in intellectual and behavioral impairments, facial paralysis, and/or later-onset axonal sensorimotor polyneuropathy. Neuroimaging reveals a spectrum of abnormalities including hypoplasia of oculomotor nerves and dysgenesis of the corpus callosum, anterior commissure, and corticospinal tracts. A knock-in disease mouse model reveals axon guidance defects without evidence of cortical cell migration abnormalities. We show that the disease-associated mutations can impair tubulin heterodimer formation in vitro, although folded mutant heterodimers can still polymerize into microtubules. Modeling each mutation in yeast tubulin demonstrates that all alter dynamic instability whereas a subset disrupts the interaction of microtubules with kinesin motors. These findings demonstrate that normal TUBB3 is required for axon guidance and maintenance in mammals.

The landscape of submicroscopic structural variants at the OPN1LW/OPN1MW gene cluster on Xq28 underlying blue cone monochromacy.

Blue cone monochromacy (BCM) is an X-linked retinal disorder characterized by low vision, photoaversion, and poor color discrimination. BCM is due to the lack of long-wavelength-sensitive and middle-wavelength-sensitive cone photoreceptor function and caused by mutations in the OPN1LW/OPN1MW gene cluster on Xq28. Here, we investigated the prevalence and the landscape of submicroscopic structural variants (SVs) at single-base resolution in BCM patients. We found that about one-third (n = 73) of the 213 molecularly confirmed BCM families carry an SV, most commonly deletions restricted to the OPN1LW/OPN1MW gene cluster. The structure and precise breakpoints of the SVs were resolved in all but one of the 73 families. Twenty-two families-all from the United States-showed the same SV, and we confirmed a common ancestry of this mutation. In total, 42 distinct SVs were identified, including 40 previously unreported SVs, thereby quadrupling the number of precisely mapped SVs underlying BCM. Notably, there was no "region of overlap" among these SVs. However, 90% of SVs encompass the upstream locus control region, an essential enhancer element. Its minimal functional extent based on deletion mapping in patients was refined to 358 bp. Breakpoint analyses suggest diverse mechanisms underlying SV formation as well as in one case the gene conversion-based exchange of a 142-bp deletion between opsin genes. Using parsimonious assumptions, we reconstructed the composition and copy number of the OPN1LW/OPN1MW gene cluster prior to the mutation event and found evidence that large gene arrays may be predisposed to the occurrence of SVs at this locus.

Complications, Visual Acuity, and Refractive Error 3 Years after Secondary Intraocular Lens Implantation for Pediatric Aphakia.

PURPOSE: To report the cumulative incidence of complications and to describe refractive error and visual acuity (VA) outcomes in children undergoing secondary intraocular lens (IOL) implantation after previous surgery for nontraumatic cataract. DESIGN: Pediatric cataract registry. PARTICIPANTS: Eighty children (108 eyes: 60 bilateral, 48 unilateral) undergoing lensectomy at younger than 13 years of age. METHODS: Annual data collection from medical record review through 5 years after lensectomy. MAIN OUTCOME MEASURES: Cumulative incidence of newly emergent complications after secondary IOL implantation; refractive error and VA by 5 years after lensectomy. RESULTS: Median follow-up after secondary IOL implantation was 2.7 years (interquartile range [IQR], 0.8-3.3 years; range, 0.6-5.0 years) for bilateral and 2.1 years (range, 0.5-6.4 years) for unilateral cases. A common complication after secondary IOL implantation was a glaucoma-related adverse event (GRAE; glaucoma or glaucoma suspect); the cumulative incidence was 17% (95% confidence interval [CI], 3%-29%) in bilateral cases and 12% (95% CI, 0%-23%) in unilateral cases. The cumulative incidence of surgery for visual axis opacification was 2% (95% CI, 0%-7%) for bilateral cases and 4% (95% CI, 0%-10%) for unilateral cases. The median prediction error within 90 days of implantation was 0.88 diopter (D; IQR, -0.50 to +3.00 D) less hyperopic than intended among 21 eyes for bilateral cases and 1.50 D (IQR, -0.25 to +2.38 D) less among 19 unilateral cases. The median spherical equivalent refractive error at 5 years (at a median of 5.1 years of age) in eyes receiving a secondary IOL was +0.50 D (IQR, -2.38 to +2.94 D) for 48 bilateral cases and +0.06 D (IQR, -2.25 to +0.75 D) for 22 unilateral cases. Median monocular VA at 5 years was 20/63 (IQR, 20/50-20/100) for bilateral cases (n = 42) and 20/400 (IQR, 20/160-20/800) for unilateral cases (n = 33). CONCLUSIONS: Eyes with secondary IOL implantation have a risk of developing new GRAEs. Five years after lensectomy (approximately 2.5 years after secondary IOL implantation), the average refractive error was less hyperopic than desired given the anticipated further myopic shift before refraction stabilizes. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

The Progression of Stargardt Disease as Determined by Spectral-Domain Optical Coherence Tomography over a 24-Month Period (ProgStar Report No. 18).

INTRODUCTION: The aim of this study was to evaluate the progression of atrophy as determined by spectral-domain optical coherence tomography (SD-OCT) in patients with molecularly confirmed ABCA4-associated Stargardt disease type 1 (STGD1) over a 24-month period in a multicenter prospective cohort study. METHODS: SD-OCT images from 428 eyes of 236 patients were analyzed. Change of mean thickness (MT) and intact area were estimated after semiautomated segmentation for the following individual layers in the central subfield (CS), inner ring (IR), and outer ring (OR) of the ETDRS grid: retinal pigment epithelium (RPE), outer segments (OSs), inner segments (IS), outer nuclear layer (ONL) inner retina (IR), and total retina. RESULTS: Statistically significant decreases of all outer retinal layers (RPE, OS, IS, and ONL) could be observed over a 24-month period both in decline of mean retinal thickness and intact area (p < 0.0001, respectively), whereas the IR showed an increase of retinal thickness in the CS and IR and remained unchanged in the OR. CONCLUSIONS: Significant loss could be detected in outer retinal layers by SD-OCT over a 24-month period in patients with STGD1. Loss of thickness and/or intact area of such layers may serve as potential endpoints for clinical trials that aim to slow down the disease progression of STGD1.

Comprehensive variant spectrum of the CNGA3 gene in patients affected by achromatopsia.

Achromatopsia (ACHM) is a congenital cone photoreceptor disorder characterized by impaired color discrimination, low visual acuity, photosensitivity, and nystagmus. To date, six genes have been associated with ACHM (CNGA3, CNGB3, GNAT2, PDE6C, PDE6H, and ATF6), the majority of these being implicated in the cone phototransduction cascade. CNGA3 encodes the CNGA3 subunit of the cyclic nucleotide-gated ion channel in cone photoreceptors and is one of the major disease-associated genes for ACHM. Herein, we provide a comprehensive overview of the CNGA3 variant spectrum in a cohort of 1060 genetically confirmed ACHM patients, 385 (36.3%) of these carrying "likely disease-causing" variants in CNGA3. Compiling our own genetic data with those reported in the literature and in public databases, we further extend the CNGA3 variant spectrum to a total of 316 variants, 244 of which we interpreted as "likely disease-causing" according to ACMG/AMP criteria. We report 48 novel "likely disease-causing" variants, 24 of which are missense substitutions underlining the predominant role of this mutation class in the CNGA3 variant spectrum. In addition, we provide extensive in silico analyses and summarize reported functional data of previously analyzed missense, nonsense and splicing variants to further advance the pathogenicity assessment of the identified variants.

TOPICAL CARBONIC ANHYDRASE INHIBITORS IN THE LONG-TERM TREATMENT OF JUVENILE X-LINKED RETINOSCHISIS.

PURPOSE: To describe the response to long-term topical dorzolamide treatment in patients with juvenile X-linked retinoschisis and cystic-like foveal lesions. METHODS: This was a retrospective interventional case series that included 18 eyes of 10 patients with genetically confirmed juvenile X-linked retinoschisis examined at the Cleveland Clinic Cole Eye Institute, a tertiary referral center, between 2005 and 2021. Patients were treated with topical 2% dorzolamide two to three times daily in both eyes. Two eyes were excluded because of retinal detachment. Primary outcome measures were logarithm of minimum angle of resolution visual acuity and optical coherence tomography based central subfield thickness. RESULTS: The mean follow-up was 8.38 years (SD, 3.41 years). The mean baseline and final central subfield thickness was 429.88 µ m (SD, 143.36 µ m) and 372.28 µ m, respectively (SD, 147.13 µ m, P = 0.10). The mean baseline and final logarithm of minimum angle of resolution visual acuity was 0.45 (SD, 0.17) and 0.34, respectively (SD, 0.22, P < 0.01). None of the patients experienced any side effects from topical dorzolamide. CONCLUSION: The study data support previous reports of improved visual acuity in X-linked retinoschisis patients on topical dorzolamide treatment. This is the longest follow-up for a series of juvenile X-linked retinoschisis patients treated with a topical carbonic anhydrase inhibitor to date. A large, prospective, randomized clinical trial is needed to provide stronger evidence regarding the efficacy of topical carbonic anhydrase inhibitors in juvenile X-linked retinoschisis.

Recessive MYF5 Mutations Cause External Ophthalmoplegia, Rib, and Vertebral Anomalies.

MYF5 is member of the Myc-like basic helix-loop-helix transcription factor family and, in cooperation with other myogenic regulatory factors MYOD and MYF5, is a key regulator of early stages of myogenesis. Here, we report three consanguineous families with biallelic homozygous loss-of-function mutations in MYF5 who define a clinical disorder characterized by congenital ophthalmoplegia with scoliosis and vertebral and rib anomalies. The clinical phenotype overlaps strikingly with that reported in several Myf5 knockout mouse models. Affected members of two families share a haploidentical region that contains a homozygous 10 bp frameshift mutation in exon 1 of MYF5 (c.23_32delAGTTCTCACC [p.Gln8Leufs∗86]) predicted to undergo nonsense-mediated decay. Affected members of the third family harbor a homozygous missense change in exon 1 of MYF5 (c.283C>T [p.Arg95Cys]). Using in vitro assays, we show that this missense mutation acts as a loss-of-function allele by impairing MYF5 DNA binding and nuclear localization. We performed whole-genome sequencing in one affected individual with the frameshift mutation and did not identify additional rare variants in the haploidentical region that might account for differences in severity among the families. These data support the direct role of MYF5 in rib, spine, and extraocular muscle formation in humans.

Outcomes of Bilateral Cataract Surgery in Infants 7 to 24 Months of Age Using the Toddler Aphakia and Pseudophakia Treatment Study Registry.

PURPOSE: To evaluate outcomes of bilateral cataract surgery in children aged 7 to 24 months and compare rates of adverse events (AEs) with other Toddler Aphakia and Pseudophakia Study (TAPS) registry outcomes. DESIGN: Retrospective clinical study at 10 Infant Aphakia Treatment Study (IATS) sites. Statistical analyses comparing this cohort with previously reported TAPS registry cohorts. PARTICIPANTS: Children enrolled in the TAPS registry between 2004 and 2010. METHODS: Children underwent bilateral cataract surgery with or without intraocular lens (IOL) placement at age 7 to 24 months with 5 years of postsurgical follow-up. MAIN OUTCOME MEASURES: Visual acuity (VA), occurrence of strabismus, AEs, and reoperations. RESULTS: A total of 40 children (76 eyes) who underwent bilateral cataract surgery with primary posterior capsulectomy were identified with a median age at cataract surgery of 11 months (7-23); 68% received a primary IOL. Recurrent visual axis opacification (VAO) occurred in 7.5% and was associated only with the use of an IOL (odds ratio, 6.10; P = 0.005). Glaucoma suspect (GS) was diagnosed in 2.5%, but no child developed glaucoma. In this bilateral cohort, AEs (8/40, 20%), including glaucoma or GS and VAO, and reoperations occurred in a similar proportion to that of the published unilateral TAPS cohort. When analyzed with children aged 1 to 7 months at bilateral surgery, the incidence of AEs and glaucoma or GS correlated strongly with age at surgery (P = 0.011/0.004) and glaucoma correlated with microcornea (P = 0.040) but not with IOL insertion (P = 0.15). CONCLUSIONS: Follow-up to age 5 years after bilateral cataract surgery in children aged 7 to 24 months reveals a low rate of VAO and very rare glaucoma or GS diagnosis compared with infants with cataracts operated at < 7 months of age despite primary IOL implantation in most children in the group aged 7 to 24 months. The use of an IOL increases the risk of VAO irrespective of age at surgery.

Outcomes of Bilateral Cataracts Removed in Infants 1 to 7 Months of Age Using the Toddler Aphakia and Pseudophakia Treatment Study Registry.

PURPOSE: To evaluate outcomes of bilateral cataract surgery in infants 1 to 7 months of age performed by Infant Aphakia Treatment Study (IATS) investigators during IATS recruitment and to compare them with IATS unilateral outcomes. DESIGN: Retrospective case series review at 10 IATS sites. PARTICIPANTS: The Toddler Aphakia and Pseudophakia Study (TAPS) is a registry of children treated by surgeons who participated in the IATS. METHODS: Children underwent bilateral cataract surgery with or without intraocular lens (IOL) placement during IATS enrollment years 2004 through 2010. MAIN OUTCOME MEASURES: Visual acuity (VA), strabismus, adverse events (AEs), and reoperations. RESULTS: One hundred seventy-eight eyes (96 children) were identified with a median age of 2.5 months (range, 1-7 months) at the time of cataract surgery. Forty-two eyes (24%) received primary IOL implantation. Median VA of the better-seeing eye at final study visit closest to 5 years of age with optotype VA testing was 0.35 logarithm of the minimum angle of resolution (logMAR; optotype equivalent, 20/45; range, 0.00-1.18 logMAR) in both aphakic and pseudophakic children. Corrected VA was excellent (<20/40) in 29% of better-seeing eyes, 15% of worse-seeing eyes. One percent showed poor acuity (≥20/200) in the better-seeing eye, 12% in the worse-seeing eye. Younger age at surgery and smaller (<9.5 mm) corneal diameter at surgery conferred an increased risk for glaucoma or glaucoma suspect designation (younger age: odds ratio [OR], 1.44; P = 0.037; and smaller cornea: OR, 3.95; P = 0.045). Adverse events also were associated with these 2 variables on multivariate analysis (younger age: OR, 1.36; P = 0.023; and smaller cornea: OR, 4.78; P = 0.057). Visual axis opacification was more common in pseudophakic (32%) than aphakic (8%) eyes (P = 0.009). Unplanned intraocular reoperation occurred in 28% of first enrolled eyes (including glaucoma surgery in 10%). CONCLUSIONS: Visual acuity after bilateral cataract surgery in infants younger than 7 months is good, despite frequent systemic and ocular comorbidities. Although aphakia management did not affect VA outcome or AE incidence, IOL placement increased the risk of visual axis opacification. Adverse events and glaucoma correlated with a younger age at surgery and glaucoma correlated with the presence of microcornea.

Homozygous stop mutation in AHR causes autosomal recessive foveal hypoplasia and infantile nystagmus.

Herein we present a consanguineous family with three children affected by foveal hypoplasia with infantile nystagmus, following an autosomal recessive mode of inheritance. The patients showed normal electroretinography responses, no signs of albinism, and no anterior segment or brain abnormalities. Upon whole exome sequencing, we identified a homozygous mutation (c.1861C>T;p.Q621*) in the aryl hydrocarbon receptor (AHR) gene that perfectly co-segregated with the disease in the larger family. AHR is a ligand-activated transcription factor that has been intensively studied in xenobiotic-induced toxicity. Further, it has been shown to play a physiological role under normal cellular conditions, such as in immunity, inflammatory response and neurogenesis. Notably, knockout of the Ahr gene in mouse impairs optic nerve myelin sheath formation and results in oculomotor deficits sharing many features with our patients: the eye movement disorder in Ahr-/- mice appears early in development and presents as conjugate horizontal pendular nystagmus. We therefore propose AHR to be a novel disease gene for a new, recessively inherited disorder in humans, characterized by infantile nystagmus and foveal hypoplasia.

Multimodal imaging in a family with Cockayne syndrome with a novel pathogenic mutation in the ERCC8 gene, and significant phenotypic variability.

BACKGROUND: Cockayne syndrome is a rare autosomal recessive neurodegenerative disorder caused by mutations of either the ERCC6/CSB or ERCC8/CSA genes. Here, we describe two sisters with Cockayne syndrome caused by compound heterozygous mutations in the ERCC8 gene using multimodal imaging. Significant ophthalmic and systemic phenotypic variability is discussed. MATERIALS AND METHODS: Multimodal imaging was performed in two affected sisters and included electroretinography, optical coherence tomography, ultra-wide-field confocal scanning laser ophthalmoscopy, fundus autofluorescence and fluorescein angiography, and magnetic resonance imaging. Genetic analyses were performed on the affected sisters, both parents, and three unaffected siblings. RESULTS: The older sister (Patient 1) had mental retardation, bilateral hearing loss, ataxia, and decreased visual acuity with retinal dystrophy. Radiographic studies revealed microcephaly, cerebral and cerebellar atrophy, ventriculomegaly, and a diffusely thickened skull. Full-field electroretinography waveforms were severely diminished with attenuation of cone and rod responses. The younger sister (Patient 2) had similar clinical features, including ataxia, bilateral hearing loss, and decreased visual acuity with retinal dystrophy. She also had paranoid schizophrenia. Wide-field fundus autofluorescence showed scattered areas of retinal pigment epithelium atrophy, which was different from her sister. Genetic analysis revealed two mutations in the ERCC8 gene shared by the sisters. These include an unreported missense point mutation: p.Thr328Ser:c.983C > G, and another previously reported pathogenic missense mutation: p.Ala205Pro:c.613G > C. Familial testing showed in trans segregation of these mutations with unaffected siblings inheriting one or neither mutation, but not both. CONCLUSION: The clinical presentation and genetic studies confirmed a diagnosis of Cockayne syndrome in both sisters caused by compound heterozygous mutations in the ERCC8 gene on chromosome 10. Multimodal ocular imaging and systemic findings revealed wide phenotypic variability between the affected siblings.

Sector retinitis pigmentosa: Report of ten cases and a review of the literature.

Purpose: To describe the genotypes and phenotypes of ten patients with sector retinitis pigmentosa (RP). We also review previously reported mutations associated with sector RP and provide a discussion of possible underlying pathophysiological mechanisms. Methods: Patients underwent detailed ophthalmologic examinations, fundus photography, fundus autofluorescence (FAF) imaging, spectral-domain optical coherence tomography (SD-OCT), as well as visual field and electroretinographic testing. All patients underwent genetic testing to identify the molecular etiology of their disease. Results: A total of ten patients were studied. Among these patients, nine had mutations in RHO (c.677T>C; p.Leu226Pro (novel), c.68C>A; p.Pro23His, c.808A>C; p.Ser270Arg, c.44A>G; p.Asn15Ser, and c.325G>A; p.Gly109Arg), and one patient had a mutation in RPGR (c.3092_3093delAG; p.Glu1031Glyfs*47). All patients with missense mutations in RHO had visual acuities (VAs) better than 20/30 and showed a retained foveal ellipsoid zone and overlying retinal structures. The patient with the c.3092_3093delAG deletion in RPGR had VA of 20/60 oculus dexter (OD) and 20/400 oculus sinister (OS), as well as significant foveal thinning and contour atrophy. All patients showed pigmentary changes, or marked atrophy along the inferior arcades, or both. This pattern of degeneration corresponded to hypo- and hyperFAF and superior visual defects. Conclusions: Sector RP is an uncommon form of RP in which only one or two retinal quadrants display clinical pathological signs. The great majority of cases result from mutations in RHO. The present data confirmed previously reported phenotypic manifestations of sector RP. Inferior retinal quadrants are possibly more severely affected due to greater light exposure.

Outcomes of Unilateral Cataracts in Infants and Toddlers 7 to 24 Months of Age: Toddler Aphakia and Pseudophakia Study (TAPS).

PURPOSE: To evaluate outcomes of unilateral cataract surgery in children 7 to 24 months of age. DESIGN: Retrospective case series at 10 Infant Aphakia Treatment Study (IATS) sites. PARTICIPANTS: The Toddler Aphakia and Pseudophakia Study is a registry of children treated by surgeons who participated in the IATS. METHODS: Children underwent unilateral cataract surgery with or without intraocular lens (IOL) placement during the IATS enrollment years of 2004 and 2010. MAIN OUTCOME MEASURES: Intraoperative complications, adverse events (AEs), visual acuity, and strabismus. RESULTS: Fifty-six children were included with a mean postoperative follow-up of 47.6 months. Median age at cataract surgery was 13.9 months (range, 7.2-22.9). Ninety-two percent received a primary IOL. Intraoperative complications occurred in 4 patients (7%). At 5 years of age, visual acuity of treated eyes was very good (≥20/40) in 11% and poor (≤20/200) in 44%. Adverse events were identified in 24%, with a 4% incidence of glaucoma suspect. An additional unplanned intraocular surgery occurred in 14% of children. Neither AEs nor intraocular reoperations were more common for children with surgery at 7 to 12 months of age than for those who underwent surgery at 13 to 24 months of age (AE rate, 21% vs. 25% [P = 0.60]; reoperation rate, 13% vs. 16% [P = 1.00]). CONCLUSIONS: Although most children underwent IOL implantation concurrent with unilateral cataract removal, the incidence of complications, reoperations, and glaucoma was low when surgery was performed between 7 and 24 months of age and compared favorably with same-site IATS data for infants undergoing surgery before 7 months of age. Our study showed that IOL implantation is relatively safe in children older than 6 months and younger than 2 years.

Stickler syndrome: exploring prophylaxis for retinal detachment.

PURPOSE OF REVIEW: The literature regarding prophylactic treatment of rhegmatogenous retinal detachment in Stickler syndrome remains controversial. We review major published clinical studies and offer a critical analysis of this subject. SUMMARY: Stickler syndrome is a systemic collagenopathy affecting multiple organ systems including the eye, ear, and skeleton. Stickler syndrome is probably the most common cause of genetically determined pediatric rhegmatogenous retinal detachment. Congenital developmental anomalies constitute over half rhegmatogenous detachments (RRD) in patients less than 10 years. The majority are caused by hereditary vitreoretinopathies associated with Stickler syndrome. Sixty percent of patients with Stickler syndrome develop RRD's over their lifetime with possible severe visual loss and subsequent lifelong morbidity. In view of these complications, some have emphasized the importance of prophylactic laser treatment to the retina of patients with Stickler syndrome to reduce the occurrence of and/or prevent future rhegmatogenous retinal detachment, but there appears to be insufficient data to support the absolute benefit of such prophylactic treatment. Guidelines regarding the age at prophylactic treatment as well as type and frequency of intervention are scarce and would benefit from additional clinical investigations.

Mutations in the gene PDE6C encoding the catalytic subunit of the cone photoreceptor phosphodiesterase in patients with achromatopsia.

Biallelic PDE6C mutations are a known cause for rod monochromacy, better known as autosomal recessive achromatopsia (ACHM), and early-onset cone photoreceptor dysfunction. PDE6C encodes the catalytic α'-subunit of the cone photoreceptor phosphodiesterase, thereby constituting an essential part of the phototransduction cascade. Here, we present the results of a study comprising 176 genetically preselected patients who remained unsolved after Sanger sequencing of the most frequent genes accounting for ACHM, and were subsequently screened for exonic and splice site variants in PDE6C applying a targeted next generation sequencing approach. We were able to identify potentially pathogenic biallelic variants in 15 index cases. The mutation spectrum comprises 18 different alleles, 15 of which are novel. Our study significantly contributes to the mutation spectrum of PDE6C and allows for a realistic estimate of the prevalence of PDE6C mutations in ACHM since our entire ACHM cohort comprises 1,074 independent families.

Identification of a mutation in CNNM4 by whole exome sequencing in an Amish family and functional link between CNNM4 and IQCB1.

We investigated an Amish family in which three siblings presented with an early-onset childhood retinal dystrophy inherited in an autosomal recessive fashion. Genome-wide linkage analysis identified significant linkage to marker D2S2216 on 2q11 with a two-point LOD score of 1.95 and a multi-point LOD score of 3.76. Whole exome sequencing was then performed for the three affected individuals and identified a homozygous nonsense mutation (c.C1813T, p.R605X) in the cyclin and CBS domain divalent metal cation transport mediator 4 (CNNM4) gene located within the 2p14-2q14 Jalili syndrome locus. The initial assessment and collection of the family were performed before the clinical delineation of Jalili syndrome. Another assessment was made after the discovery of the responsible gene and the dental abnormalities characteristic of Jalili syndrome were retrospectively identified. The p.R605X mutation represents the first probable founder mutation of Jalili syndrome identified in the Amish community. The molecular mechanism underlying Jalili syndrome is unknown. Here we show that CNNM4 interacts with IQCB1, which causes Leber congenital amaurosis (LCA) when mutated. A truncated CNNM4 protein starting at R605 significantly increased the rate of apoptosis, and significantly increased the interaction between CNNM4 and IQCB1. Mutation p.R605X may cause Jalili syndrome by a nonsense-mediated decay mechanism, affecting the function of IQCB1 and apoptosis, or both. Our data, for the first time, functionally link Jalili syndrome gene CNNM4 to LCA gene IQCB1, providing important insights into the molecular pathogenic mechanism of retinal dystrophy in Jalili syndrome.

ELLIPSOID ZONE MAPPING AND OUTER RETINAL ASSESSMENT IN STARGARDT DISEASE.

PURPOSE: To quantify and correlate ellipsoid zone and photoreceptor outer segment changes with visual acuity in Stargardt disease. METHODS: An institutional review board-approved study of 32 eyes with Stargardt disease was performed. After spectral domain optical coherence tomography, the macular cube was exported into a novel analysis tool and volumetric assessment from the ellipsoid zone to the retinal pigment epithelium was performed. Using this information, mapping was completed with en face representation of the height between the ellipsoid zone and retinal pigment epithelium. This analysis provided quantification of ellipsoid zone and photoreceptor outer segments, including atrophy (ellipsoid zone to retinal pigment epithelium thickness = 0 µm) and attenuation (ellipsoid zone to retinal pigment epithelium thickness <20 µm). These parameters were compared with visual acuity and controls (n = 12 eyes). RESULTS: Visual acuity ranged from 20/30 to 20/250. The central foveal B-scan area of ellipsoid and photoreceptor outer segments was significantly less than controls (0.13 ± 0.05 mm vs. 0.17 ± 0.03 mm, respectively, P = 0.0074). The central foveal B-scan mean thickness measured 22.52 ± 9.0 µm in Stargardt versus 30.0 ± 5.08 µm (P = 0.0096). Atrophy and attenuation were significantly higher in Stargardt patients (22% vs. 1%, P = 0.005 and 43% vs. 1%, P = 0.0002). Visual acuity directly correlated with ellipsoid zone/outer segment volume (R = 0.57, P < 0.005) and inversely correlated with attenuation and atrophy (R = -0.53 and -0.57; P < 0.005 for all). CONCLUSION: Eyes with Stargardt disease frequently have significant disruption of the ellipsoid zone and outer segments. This degenerative change was successfully quantified with a novel assessment platform and identified correlates with visual function. This software provides the opportunity for quantitative assessment and possible longitudinal surveillance.

Mutations in ASPH cause facial dysmorphism, lens dislocation, anterior-segment abnormalities, and spontaneous filtering blebs, or Traboulsi syndrome.

We have previously described a syndrome characterized by facial dysmorphism, lens dislocation, anterior-segment abnormalities, and spontaneous filtering blebs (FDLAB, or Traboulsi syndrome). In view of the consanguineous nature of the affected families and the likely autosomal-recessive inheritance pattern of this syndrome, we undertook autozygosity mapping and whole-exome sequencing to identify ASPH as the disease locus, in which we identified two homozygous mutations. ASPH encodes aspartyl/asparaginyl ß-hydroxylase (ASPH), which has been found to hydroxylate aspartic acid and asparagine residues on epidermal growth factor (EGF)-domain-containing proteins. The truncating and missense mutations we identified are predicted to severely impair the enzymatic function of ASPH, which suggests a possible link to other forms of ectopia lentis given that many of the genes implicated in this phenotype encode proteins that harbor EGF domains. Developmental analysis of Asph revealed an expression pattern consistent with the proposed link to the human syndrome. Indeed, Asph-knockout mice had a foreshortened snout, which corresponds to the facial abnormalities in individuals with Traboulsi syndrome. These data support a genetic basis for a syndromic form of ectopia lentis and the role of aspartyl hydroxylation in human development.

The Natural History of the Progression of Atrophy Secondary to Stargardt Disease (ProgStar) Studies: Design and Baseline Characteristics: ProgStar Report No. 1.

PURPOSE: To describe the design and baseline characteristics of patients enrolled into 2 natural history studies of Stargardt disease (STGD1). DESIGN: Multicenter retrospective and prospective cohort studies. PARTICIPANTS: Three hundred sixty-five unique patients aged 6 years and older at baseline harboring disease-causing variants in the ABCA4 gene and with specified ocular lesions were enrolled from 9 centers in the United States and Europe. METHODS: In the retrospective study, patients contributed medical record data from at least 2 and up to 4 visits for at least 1 examination modality: fundus autofluorescence (FAF), spectral-domain (SD) optical coherence tomography (SD OCT), and/or microperimetry (MP). The total observational period was at least 2 years and up to 5 years between single visits. Demographic and visual acuity (VA) data also were obtained. In the prospective study, eligible patients were examined at baseline using a standard protocol, with 6-month follow-up visits planned for a 2-year period for serial Early Treatment Diabetic Retinopathy Study (ETDRS) best-corrected VA, SD OCT, FAF, and MP. MAIN OUTCOME MEASURES: Design and rationale of a multicenter study to determine the progression of STGD1 in 2 large retrospective and prospective international cohorts. Detailed baseline characteristics of both cohorts are presented, including demographics, and structural and functional retinal metrics. RESULTS: Into the retrospective study, 251 patients (458 eyes) were enrolled; mean follow-up ± standard deviation was 3.9±1.6 years. At baseline, 36% had no or mild VA loss, and 47% of the study eyes had areas of definitely decreased autofluorescence (DDAF) with an average lesion area of 2.5±2.9 mm(2) (range, 0.02-16.03 mm(2)). Two hundred fifty-nine patients (489 eyes) were enrolled in the prospective study. At baseline, 20% had no or mild VA loss, and 64% had areas of DDAF with an average lesion area of 4.0±4.4 mm(2) (range, 0.03-24.24 mm(2)). The mean retinal sensitivity with MP was 10.8±5.0 dB. CONCLUSIONS: The ProgStar cohorts have baseline characteristics that encompass a wide range of disease severity and are expected to provide valuable data on progression based on serial quantitative measurements derived from multiple methods, which will be critical to the design of planned clinical trials.