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Usher syndrome (USH) is the most common cause of deafblindness. USH is autosomal recessively inherited and characterized by rod‐cone dystrophy or retinitis pigmentosa (RP), often accompanied by sensorineural hearing loss. Variants in >15 genes have been identified as causative for clinically and genetically distinct subtypes. Among the ultra‐rare and recently discovered genes is ARSG, coding for the lysosomal sulfatase Arylsulfatase G. This subtype was assigned as “USH IV” with a late onset of RP and usually late‐onset progressive SNHL without vestibular involvement. Here, we describe nine new subjects and the clinical description of four cases with the USH IV phenotype bearing seven novel and two known pathogenic variants. Functional experiments indicated the complete loss of sulfatase enzymatic activity upon ectopic expression of mutated ARSG cDNA. Interestingly, we identified a homozygous missense variant, p.(Arg99His), previously described in dogs with neuronal ceroid lipofuscinosis. Our study expands the genetic landscape of ARSG‐USH IV and the number of known subjects by more than 30%. These findings highlight that USH IV likely has been underdiagnosed and emphasize the need to test molecularly unresolved subjects with deafblindness syndrome. Finally, testing of ARSG should be considered for the genetic work‐up of apparent isolated inherited retinal diseases. [ABSTRACT FROM AUTHOR]

An abstract of the article "Phenotype Evolution in Xeroderma Pigmentosum/Cockayne Syndrome," by Elizabeth R. Heller and colleagues is presented.

We aimed to characterize the ocular phenotype of patients with ROSAH (retinal dystrophy, optic nerve edema, splenomegaly, anhidrosis, and headache) syndrome and their response to therapy. Single-center observational case study. Eleven patients with a diagnosis of ROSAH syndrome and mutation in ALPK1 were included. Patients with molecularly confirmed ROSAH syndrome underwent ophthalmic evaluation, including visual acuity testing, slit-lamp and dilated examinations, color fundus and autofluorescence imaging, fluorescein angiography, OCT, and electrophysiologic testing. Visual acuity, electrophysiology, fluorescein angiography, and OCT findings. Eleven individuals (6 female and 5 male patients) from 7 families ranging in age from 7.3 to 60.2 years at the time of the initial evaluation were included in this study. Seven patients were followed up for a mean of 2.6 years (range, 0.33–5.0 years). Best-corrected visual acuity at baseline ranged from 20/16 to no light perception. Variable signs or sequelae of intraocular inflammation were observed in 9 patients, including keratic precipitates, band keratopathy, trace to 2+ anterior chamber cells, cystoid macular edema, and retinal vasculitis on fluorescein angiography. Ten patients were observed to show optic disc elevation and demonstrated peripapillary thickening on OCT. Seven patients showed retinal degeneration consistent with a cone–rod dystrophy, with atrophy tending to involve the posterior pole and extending peripherally. One patient with normal electroretinography findings and visual evoked potential was found to have decreased Arden ratio on electro-oculography. Leveraging insights from the largest single-center ROSAH cohort described to date, this study identified 3 main factors as contributing to changes in visual function of patients with ROSAH syndrome: optic nerve involvement; intraocular inflammation, including cystoid macular edema; and retinal degeneration. More work is needed to determine how to arrest the progressive vision loss associated with ROSAH syndrome. Proprietary or commercial disclosure may be found after the references. [ABSTRACT FROM AUTHOR]

Background: Infantile neuronal ceroid lipofuscinosis is a devastating neurodegenerative lysosomal storage disease caused by mutations in the gene (CLN1 or PPT1) encoding palmitoyl-protein thioesterase-1 (PPT1). We have previously reported that phosphocysteamine and N-acetylcysteine mediate ceroid depletion in cultured cells from patients with this disease. We aimed to assess whether combination of oral cysteamine bitartrate and N-acetylcysteine is beneficial for patients with neuronal ceroid lipofuscinosis. Methods: Children between 6 months and 3 years of age with infantile neuronal ceroid lipofuscinosis with any two of the seven most lethal PPT1 mutations were eligible for inclusion in this pilot study. All patients were recruited from physician referrals. Patients received oral cysteamine bitartrate (60 mg/kg per day) and N-acetylcysteine (60 mg/kg per day) and were assessed every 6-12 months until they had an isoelectric electroencephalogram (EEG, attesting to a vegetative state) or were too ill to travel. Patients were also assessed by electroretinography, brain MRI and magnetic resonance spectroscopy (MRS), and electron microscopic analyses of leukocytes for granular osmiophilic deposits (GRODs). Children also underwent physical and neurodevelopmental assessments on the Denver scale. Outcomes were compared with the reported natural history of infantile neuronal ceroid lipofuscinosis and that of affected older siblings. This trial is registered with ClinicalTrials.gov, number NCT00028262. Findings: Between March 14, 2001, and June 30, 2012, we recruited ten children with infantile neuronal ceroid lipofuscinosis; one child was lost to follow-up after the first visit and nine patients (five girls and four boys) were followed up for 8 to 75 months. MRI showed abnormalities similar to those in previous reports; brain volume and N-acetyl aspartic acid (NAA) decreased steadily, but no published quantitative MRI or MRS studies were available for comparison. None of the children acquired new developmental skills, and their retinal function decreased progressively. Average time to isoelectric EEG (52 months, SD 13) was longer than reported previously (36 months). At the first follow-up visit, peripheral leukocytes in all nine patients showed virtually complete depletion of GRODs. Parents and physicians reported less irritability, improved alertness, or both in seven patients. No treatment-related adverse events occurred apart from mild gastrointestinal discomfort in two patients, which disappeared when liquid cysteamine bitartrate was replaced with capsules. Interpretation: Our findings suggest that combination therapy with cysteamine bitartrate and N-acetylcysteine is associated with delay of isoelectric EEG, depletion of GRODs, and subjective benefits as reported by parents and physicians. Our systematic and quantitative report of the natural history of patients with infantile neuronal ceroid lipofuscinosis provides a guide for future assessment of experimental therapies. Funding: National Institutes of Health. [ABSTRACT FROM AUTHOR]

The retinal dystrophy phenotype associated with CDHR1 retinopathy is clinically heterogenous. In this study, we describe the clinical and molecular findings of a retinal dystrophy cohort (10 patients) attributed to autosomal recessive CDHR1 and report novel variants in populations not previously identified with CDHR1-related retinopathy. Seven patients had evaluations covering at least a three-year period. The mean age of individuals at first symptoms was 36 ± 8.5 years (range 5–45 years). Visual acuity at the last visit ranged from 20/20 to 20/2000 (mean LogMAR 0.8 or 20/125). Three clinical subgroups were identified: rod–cone dystrophy (RCD), cone–rod dystrophy (CRD), and maculopathy. Extinguished scotopic electroretinography responses were noted in the RCD patients. Macular involvement was noted in all patients and documented on color fundus photography, fundus autofluorescence, and optical coherence tomography. Notable asymmetry of the degree of macular atrophy was present in two patients. The possible association between CDHR1 variants and clinical findings was predicted using molecular modeling. [ABSTRACT FROM AUTHOR]

Atypical Usher syndrome (USH) is poorly defined with a broad clinical spectrum. Here, we characterize the clinical phenotype of disease caused by variants in CEP78, CEP250, ARSG, and ABHD12. Chart review evaluating demographic, clinical, imaging, and genetic findings of 19 patients from 18 families with a clinical diagnosis of retinal disease and confirmed disease-causing variants in CEP78, CEP250, ARSG, or ABHD12. CEP78-related disease included sensorineural hearing loss (SNHL) in 6/7 patients and demonstrated a broad phenotypic spectrum including: vascular attenuation, pallor of the optic disc, intraretinal pigment, retinal pigment epithelium mottling, areas of mid-peripheral hypo-autofluorescence, outer retinal atrophy, mild pigmentary changes in the macula, foveal hypo-autofluorescence, and granularity of the ellipsoid zone. Nonsense and frameshift variants in CEP250 showed mild retinal disease with progressive, non-congenital SNHL. ARSG variants resulted in a characteristic pericentral pattern of hypo-autofluorescence with one patient reporting non-congenital SNHL. ABHD12-related disease showed rod-cone dystrophy with macular involvement, early and severe decreased best corrected visual acuity, and non-congenital SNHL ranging from unreported to severe. This study serves to expand the clinical phenotypes of atypical USH. Given the variable findings, atypical USH should be considered in patients with peripheral and macular retinal disease even without the typical RP phenotype especially when SNHL is noted. Additionally, genetic screening may be useful in patients who have clinical symptoms and retinal findings even in the absence of known SNHL given the variability of atypical USH. [ABSTRACT FROM AUTHOR]

Optimal lysosome function requires maintenance of an acidic pH maintained by proton pumps in combination with a counterion transporter such as the Cl−/H+ exchanger, CLCN7 (ClC-7), encoded by CLCN7. The role of ClC-7 in maintaining lysosomal pH has been controversial. In this paper, we performed clinical and genetic evaluations of two children of different ethnicities. Both children had delayed myelination and development, organomegaly, and hypopigmentation, but neither had osteopetrosis. Whole-exome and -genome sequencing revealed a de novo c.2144A>G variant in CLCN7 in both affected children. This p.Tyr715Cys variant, located in the C-terminal domain of ClC-7, resulted in increased outward currents when it was heterologously expressed in Xenopus oocytes. Fibroblasts from probands displayed a lysosomal pH approximately 0.2 units lower than that of control cells, and treatment with chloroquine normalized the pH. Primary fibroblasts from both probands also exhibited markedly enlarged intracellular vacuoles; this finding was recapitulated by the overexpression of human p.Tyr715Cys CLCN7 in control fibroblasts, reflecting the dominant, gain-of-function nature of the variant. A mouse harboring the knock-in Clcn7 variant exhibited hypopigmentation, hepatomegaly resulting from abnormal storage, and enlarged vacuoles in cultured fibroblasts. Our results show that p.Tyr715Cys is a gain-of-function CLCN7 variant associated with developmental delay, organomegaly, and hypopigmentation resulting from lysosomal hyperacidity, abnormal storage, and enlarged intracellular vacuoles. Our data supports the hypothesis that the ClC-7 antiporter plays a critical role in maintaining lysosomal pH. [ABSTRACT FROM AUTHOR]

Purpose To characterize the ocular phenotype of DICER1 syndrome. Design Prospective, single-center, case-control study. Participants One hundred three patients with an identified germline pathogenic DICER1 variant (DICER1 carriers) and 69 family control participants underwent clinical and ophthalmic examination at the National Institutes of Health between 2011 and 2016. Methods All participants were evaluated with a comprehensive ophthalmic examination, including best-corrected visual acuity, slit-lamp biomicroscopy, and a dilated fundus examination. A subset of patients returned for a more detailed evaluation including spectral-domain OCT, color fundus photography, fundus autofluorescence imaging, visual field testing, full-field electroretinography, and genetic testing for inherited retinal degenerative diseases. Main Outcome Measures Visual acuity and examination findings. Results Most DICER1 carriers (97%) maintained a visual acuity of 20/40 or better in both eyes. Twenty-three DICER1 carriers (22%) showed ocular abnormalities compared with 4 family controls (6%; P = 0.005). These abnormalities included retinal pigment abnormalities (n = 6 [5.8%]), increased cup-to-disc ratio (n = 5 [4.9%]), optic nerve abnormalities (n = 2 [1.9%]), epiretinal membrane (n = 2 [1.9%]), and drusen (n = 2 [1.9%]). Overall, we observed a significant difference (P = 0.03) in the rate of retinal abnormalities in DICER1 carriers (n = 11 [11%]) versus controls (n = 1 [1.5%]). One patient demonstrated an unexpected diagnosis of retinitis pigmentosa with a novel variant of unknown significance in PRPF31 , and 1 showed optic nerve elevation in the setting of increased intracranial pressure (ICP) of unclear cause. Three patients (3%) demonstrated DICER1 -related ciliary body medulloepithelioma (CBME), 2 of which were identified during routine examination, a higher rate than that reported previously. Conclusions Ophthalmologists should be aware of the ophthalmic manifestations of DICER1 syndrome, and individuals and families should be counseled on the potential signs and symptoms. We recommend that children with a germline pathogenic variant in DICER1 , especially those younger than 10 years, undergo annual dilated ophthalmic examination, looking for evidence of CBME, signs of increased ICP, and perhaps changes in the retinal pigment epithelium. [ABSTRACT FROM AUTHOR]

PIGT-CDG, an autosomal recessive syndromic intellectual disability disorder of glycosylphosphatidylinositol (GPI) anchors, was recently described in two independent kindreds [Multiple Congenital Anomalies-Hypotonia-Seizures Syndrome 3 (OMIM, #615398)]. PIGT encodes phosphatidylinositol-glycan biosynthesis class T, a subunit of the heteropentameric transamidase complex that facilitates the transfer of GPI to proteins. GPI facilitates attachment (anchoring) of proteins to cell membranes. We describe, at ages 7 and 6 years, two children of non-consanguineous parents; they had hypotonia, severe global developmental delay, and intractable seizures along with endocrine, ophthalmologic, skeletal, hearing, and cardiac anomalies. Exome sequencing revealed that both siblings had compound heterozygous variants in PIGT (NM_015937.5), i.e., c.918dupC, a novel duplication leading to a frameshift, and c.1342C > T encoding a previously described missense variant. Flow cytometry studies showed decreased surface expression of GPI-anchored proteins on granulocytes, consistent with findings in previous cases. These siblings further delineate the clinical spectrum of PIGT-CDG, reemphasize the neuro-ophthalmologic presentation, clarify the endocrine features, and add hypermobility, low CSF albumin quotient, and hearing loss to the phenotypic spectrum. Our results emphasize that GPI anchor-related congenital disorders of glycosylation (CDGs) should be considered in subjects with early onset severe seizure disorders and dysmorphic facial features, even in the presence of a normal carbohydrate-deficient transferrin pattern and N-glycan profiling. Currently available screening for CDGs will not reliably detect this family of disorders, and our case reaffirms that the use of flow cytometry and genetic testing is essential for diagnosis in this group of disorders. [ABSTRACT FROM AUTHOR]

PURPOSE: To investigate the frequency and types of systemic findings in patients with apparently isolated uveal coloboma. DESIGN: Cross-sectional observational study. METHODS: SETTING: Single-center ophthalmic genetics clinic. STUDY POPULATION: Ninety-nine patients with uveal coloboma seen at theNationalEye Institute. OBSERVATIONAL PROCEDURE: Results of audiology testing, echocardiogram, brain magnetic resonance imaging, renal ultrasound, and total spine radiographs. MAIN OUTCOME MEASURE: Prevalence of abnormal findings on systemic testing. RESULTS: Uveal coloboma affected only the anterior segment in 8 patients, only the posterior segment in 23 patients, and both anterior and posterior segments in 68 patients. Best-corrected visual acuity (BCVA) of eyes with coloboma was ≥20/40 in 45% of eyes; 23% of eyes had BCVA of ≤20/400. The majority of patients (74%) had good vision (>20/60) in at least 1 eye. Ten of the 19 patients (53%) who underwent echocardiography had abnormalities, with ventral septal defects being the most prevalent. Abnormal findings were observed in 5 of 72 patients (7%) who had a renal ultrasound and in 5 of 29 patients (17%) who underwent a brain MRI. Audiology testing revealed abnormalities in 13 of 75 patients (17%), and spine radiographs showed anomalies in 10 of 77 patients (13%). Most findings required no acute intervention. CONCLUSIONS: Although some patients with coloboma had evidence of extraocular abnormalities, the majority of findings on routine clinical examination did not require acute intervention, but some warranted follow-up. Results from the systemic evaluation of patients with coloboma should be interpreted with caution and in view of their clinical context. [ABSTRACT FROM AUTHOR]

Background: Determining the etiology of oculocutaneous albinism is important for proper clinical management and to determine prognosis. The purpose of this study was to genotype and phenotype eight adopted Chinese children who presented with oculocutaneous albinism and easy bruisability.Results: The patients were evaluated at a single center; their ages ranged from 3 to 8 years. Whole exome or direct sequencing showed that two of the children had Hermansky-Pudlak syndrome (HPS) type-1 (HPS-1), one had HPS-3, one had HPS-4, and four had non-syndromic oculocutaneous albinism associated with TYR variants (OCA1). Two frameshift variants in HPS1 (c.9delC and c.1477delA), one nonsense in HPS4 (c.416G > A), and one missense variant in TYR (c.1235C > T) were unreported. The child with HPS-4 is the first case with this subtype reported in the Chinese population. Hypopigmentation in patients with HPS was mild compared to that in OCA1 cases, who had severe pigment defects. Bruises, which may be more visible in patients with hypopigmentation, were found in all cases with either HPS or OCA1. Whole mount transmission electron microscopy demonstrated absent platelet dense granules in the HPS cases; up to 1.9 mean dense granules per platelet were found in those with OCA1. Platelet aggregation studies in OCA1 cases were inconclusive.Conclusions: Clinical manifestations of oculocutaneous albinism and easy bruisability may be observed in children with HPS or OCA1. Establishing definitive diagnoses in children presenting with these phenotypic features is facilitated by genetic testing. Non-syndromic oculocutaneous albinism and various HPS subtypes, including HPS-4, are found in children of Chinese ancestry. [ABSTRACT FROM AUTHOR]

Age-related macular degeneration (AMD), a complex neurodegenerative disease, is a leading cause of visual impairment worldwide with a strong genetic component. Genetic studies have identified several loci, but few causal genes with functional characterization. Here we highlight multiple lines of evidence which show a causal role in AMD for SLC16A8, which encodes MCT3, a retinal pigment epithelium (RPE) specific lactate transporter. First, in an unbiased, genome-wide analysis of rare coding variants we show multiple SLC16A8 rare variants are associated with AMD risk, corroborating previous borderline significant reports from AMD rare variant studies. Second, we report a novel SLC16A8 mutation in a three-generation family with early onset macular degeneration. Finally, mis-expression in multiple model organisms shows functional and anatomic retinal consequences. This study highlights the important role for SLC16A8 and lactate regulation towards outer retina/RPE health and highlights a potential new therapeutic opportunity for the treatment of AMD., (© 2024. The Author(s).)

Purpose: Hereditary eye diseases (HEDs) are individually rare but affect millions globally. The era of molecular genetics has ushered major advances in the study of these disorders; however, the inclusivity and population diversity of this research is unknown. Questions on the accuracy and applicability of these findings in diverse populations, especially African American patients, came up consistently during counselling sessions. This also raised the possibility of missed opportunities for broader understanding of these rare diseases. We conducted a literature review to measure the representation of African Americans in genomic research surrounding nine HEDs., Methods: A detailed literature search using a predetermined set of search terms for each of nine HED categories was performed across PubMed, Embase, Web of Science, and Scopus focusing on studies published between Jan 1990 and July 2021. Predetermined inclusion criteria were applied to filter the sources., Results: We identified 46 studies clearly reporting HED characterization in African Americans. Analysis of these inclusive studies revealed unique findings demonstrating the known usefulness of including diverse cohorts in genomics research., Conclusions: HED characterization in diverse participants, specifically African Americans, is identified as a knowledge gap area. Genomic research is more applicable to patients when conducted in populations that share their ancestral background. Greater inclusion of African Americans in ophthalmic genetics research is a scientific imperative and a needed step in the pursuit of the best possible patient care for populations of all ancestries., Translational Relevance: This work reveals gaps in genomic research in African Americans with HEDs.

Purpose: GM1 gangliosidosis (GM1) a lysosomal disorder caused by pathogenic variants in GLB1, is characterized by relentless neurodegeneration. There are no approved treatments., Methods: Forty-one individuals with type II (late-infantile and juvenile) GM1 participated in a single-site prospective observational study., Results: Classification of 37 distinct variants using American College of Medical Genetics and Genomics criteria resulted in the upgrade of 6 and the submission of 4 new variants. In contrast to type I infantile disease, children with type II had normal or near normal hearing and did not have cherry-red maculae or hepatosplenomegaly. Some older children with juvenile onset disease developed thickened aortic and/or mitral valves. Serial magnetic resonance images demonstrated progressive brain atrophy, more pronounced in late infantile patients. Magnetic resonance spectroscopy showed worsening elevation of myo-inositol and deficit of N-acetyl aspartate that were strongly correlated with scores on the Vineland Adaptive Behavior Scale, progressing more rapidly in late infantile compared with juvenile onset disease., Conclusion: Serial phenotyping of type II GM1 patients expands the understanding of disease progression and clarifies common misconceptions about type II patients; these are pivotal steps toward more timely diagnosis and better supportive care. The data amassed through this 10-year effort will serve as a robust comparator for ongoing and future therapeutic trials., Competing Interests: Conflict of Interest Adam L. Hartman receives consulting fees from Teladoc. All other authors declare no conflicts of interest., (Published by Elsevier Inc.)

Purpose: To describe a novel optical coherence tomography (OCT) finding of outer retina microcavitations in RP1 -related retinopathy and other retinal degenerations., Methods: Medical charts and OCT images of 28 patients with either autosomal dominant retinitis pigmentosa or autosomal recessive retinitis pigmentosa RP1 -related retinopathy were reviewed. Outer retina microcavitations were defined as hyporeflective OCT structures of at least 30 µ m in diameter between the ellipsoid zone and retinal pigment epithelium. Comparison was made based on the following metrics: (1) functional measures including best-corrected visual acuity and color discrimination errors on D-15 test; and (2) structural measures, including central subfield, average macular thickness, and preserved transfoveal ellipsoid zone width. Mann-Whitney tests were used for comparisons with significance set at P < 0.05. The specificity of microcavitations for RP1 -related retinopathy was estimated against 26 patients with non- RP1 retinitis pigmentosa., Results: Among 15 included patients, microcavitations were found in at least one eye of all patients with arRP and 7/12 (58%) of patients with adRP. Patients with adRP and microcavitations were older at the time of examination (51 vs. 43 years of age; P = 0.04) and their eyes demonstrated worse best-corrected visual acuity (0.09 vs. 0 logMAR; P = 0.008), reduced central subfield (256 vs. 293 µ m; P = 0.01), average macular thickness (241 vs. 270 µ m; P = 0.02), and shorter transfoveal ellipsoid zone widths (1.67 vs. 4.98 mm; P < 0.0001). The finding of microcavitations showed a specificity of 0.92 for RP1 -related retinopathy., Conclusion: A novel OCT finding of outer retina microcavitations was commonly observed in patients with RP1 -related retinopathy. Eyes with outer retinal OCT microcavitations had worse visual function and more affected central retinal structure.

Purpose: To describe and evaluate a novel method to determine the validity of measurements made using cycle-by-cycle (CxC) recording techniques in patients with advanced retinal degenerations (RD) having low-amplitude flicker electroretinogram (ERG) responses., Methods: The method extends the original CxC recording algorithm introduced by Sieving et al., retaining the original recording setup and the preliminary analysis of raw data. Novel features include extended use of spectrum analysis, reduction of errors due to known sources, and a comprehensive statistical assessment using three different tests. The method was applied to ERG recordings from seven patients with RD and two patients with CNGB3 achromatopsia., Results: The method was implemented as a Windows application to processes raw data obtained from a commercial ERG system, and it features a computational toolkit for statistical assessment of ERG recordings with amplitudes as low as 1 µV, commonly found in advanced RD patients. When recorded using conditions specific for eliciting cone responses, none of the CNGB3 patients had a CxC validated response, indicating that no signal artifacts were present with our recording conditions. A comparison of the presented method with conventional 30 Hz ERG was performed. Bland-Altman plots indicated good agreement (mean difference, -0.045 µV; limits of agreement, 0.193 to -0.282 µV) between the resulting amplitudes. Within-session test-retest variability was 15%, comparing favorably to the variability of standard ERG amplitudes., Conclusions: This novel method extracts highly reliable clinical recordings of low-amplitude flicker ERGs and effectively detects artifactual responses. It has potential value both as a cone outcome variable and planning tool in clinical trials on natural history and treatment of advanced RDs.

Background: Giant axonal neuropathy is a rare, autosomal recessive, pediatric, polysymptomatic, neurodegenerative disorder caused by biallelic loss-of-function variants in GAN , the gene encoding gigaxonin., Methods: We conducted an intrathecal dose-escalation study of scAAV9/JeT-GAN (a self-complementary adeno-associated virus-based gene therapy containing the GAN transgene) in children with giant axonal neuropathy. Safety was the primary end point. The key secondary clinical end point was at least a 95% posterior probability of slowing the rate of change (i.e., slope) in the 32-item Motor Function Measure total percent score at 1 year after treatment, as compared with the pretreatment slope., Results: One of four intrathecal doses of scAAV9/JeT-GAN was administered to 14 participants - 3.5×10 13 total vector genomes (vg) (in 2 participants), 1.2×10 14 vg (in 4), 1.8×10 14 vg (in 5), and 3.5×10 14 vg (in 3). During a median observation period of 68.7 months (range, 8.6 to 90.5), of 48 serious adverse events that had occurred, 1 (fever) was possibly related to treatment; 129 of 682 adverse events were possibly related to treatment. The mean pretreatment slope in the total cohort was -7.17 percentage points per year (95% credible interval, -8.36 to -5.97). At 1 year after treatment, posterior mean changes in slope were -0.54 percentage points (95% credible interval, -7.48 to 6.28) with the 3.5×10 13 -vg dose, 3.23 percentage points (95% credible interval, -1.27 to 7.65) with the 1.2×10 14 -vg dose, 5.32 percentage points (95% credible interval, 1.07 to 9.57) with the 1.8×10 14 -vg dose, and 3.43 percentage points (95% credible interval, -1.89 to 8.82) with the 3.5×10 14 -vg dose. The corresponding posterior probabilities for slowing the slope were 44% (95% credible interval, 43 to 44); 92% (95% credible interval, 92 to 93); 99% (95% credible interval, 99 to 99), which was above the efficacy threshold; and 90% (95% credible interval, 89 to 90). Between 6 and 24 months after gene transfer, sensory-nerve action potential amplitudes increased, stopped declining, or became recordable after being absent in 6 participants but remained absent in 8., Conclusions: Intrathecal gene transfer with scAAV9/JeT-GAN for giant axonal neuropathy was associated with adverse events and resulted in a possible benefit in motor function scores and other measures at some vector doses over a year. Further studies are warranted to determine the safety and efficacy of intrathecal AAV-mediated gene therapy in this disorder. (Funded by the National Institute of Neurological Disorders and Stroke and others; ClinicalTrials.gov number, NCT02362438.)., (Copyright © 2024 Massachusetts Medical Society.)

Background/aims: To characterise the ocular manifestations of Williams-Beuren syndrome (WBS) and compare these to patients with isolated elastin mediated supravalvular aortic stenosis (SVAS)., Methods: Fifty-seven patients with a diagnosis of WBS and five with SVAS underwent comprehensive ophthalmic evaluation at the National Institutes of Health from 2017 to 2020, including best-corrected visual acuity, slit-lamp biomicroscopy, optical biometry, dilated fundus examination, optical coherence tomography and colour fundus imaging., Results: Mean age of the 57 WBS patients was 20.3 years (range 3-60 years). Best-corrected visual acuity ranged from 20/20 to 20/400 with mean spherical equivalent near plano OU. Twenty-four eyes (21.8%) had an axial length (AL) less than 20.5 mm and 38 eyes (34.5%) had an AL measuring 20.5-22.0 mm. Stellate iris and retinal arteriolar tortuosity were noted in 30 (52.6%) and 51 (89.5%) WBS patients, respectively. Novel retinal findings in WBS included small hypopigmented retinal deposits (OD 29/57, OS 27/57) and broad foveal pit contour (OD 44/55, OS 42/51). Of the five patients with SVAS, none had stellate iris or broad foveal pit contour while 2/5 had retinal arteriolar tortuosity., Conclusion: WBS is a complex multisystem genetic disorder with diverse ophthalmic findings that differ from those seen in isolated elastin mediated SVAS. These results suggest other genes within the WBS critical region, aside from ELN , may be involved in observed ocular phenotypes and perhaps broader ocular development. Furthermore, retinal arteriolar tortuosity may provide future insight into systemic vascular findings in WBS., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2023. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Purpose: To systematically assess the ability to detect change and retest reliability for a panel of visual function assessments in ABCA4 retinopathy., Design: Prospective natural history study (NCT01736293)., Methods: Patients with at least 1 documented pathogenic ABCA4 variant and a clinical phenotype consistent with ABCA4 retinopathy were recruited from a tertiary referral center. Participants underwent longitudinal, multifaceted functional testing, including measures of function at fixation (best-corrected visual acuity, low-vision Cambridge Color Test), macular function (microperimetry), and retina-wide function (full-field electroretinography [ERG]). Two- and 5-year ability to detect change was determined based on the η 2 statistic., Results: A total of 134 eyes from 67 participants with a mean follow-up of 3.65 years were included. In the 2-year interval, the microperimetry-derived perilesional sensitivity (η 2 of 0.73 [0.53, 0.83]; -1.79 dB/y [-2.2, -1.37]) and mean sensitivity (η 2 of 0.62 [0.38, 0.76]; -1.28 dB/y [-1.67, -0.89]) showed most change over time, but could only be recorded in 71.6% of the participants. In the 5-year interval, the dark-adapted ERG a- and b-wave amplitude showed marked change over time as well (eg, DA 30 a-wave amplitude with an η 2 of 0.54 [0.34, 0.68]; -0.02 log 10 (µV)/y [-0.02, -0.01]). The genotype explained a large fraction of variability in the ERG-based age of disease initiation (adjusted R 2 of 0.73) CONCLUSIONS: Microperimetry-based clinical outcome assessments were most sensitive to change but could only be acquired in a subset of participants. Across a 5-year interval, the ERG DA 30 a-wave amplitude was sensitive to disease progression, potentially allowing for more inclusive clinical trial designs encompassing the whole ABCA4 retinopathy spectrum., (Published by Elsevier Inc.)

Purpose: To describe a group of patients with retinitis pigmentosa GTPase regulator (RPGR)-related retinopathy with a tapetal-like retinal sheen and corresponding changes in the reflectivity of the ellipsoid zone on optical coherence tomography (OCT) imaging., Methods: A retrospective case series of 66 patients with a disease-causing variant in RPGR was performed. An expert examiner, masked to patient demographics, clinical evaluations, and specific RPGR variant, analyzed color fundus photographs for the presence of a tapetal-like retinal sheen and assessed OCT images for the presence of an abnormally broad hyper-reflective band in the outer retina. Longitudinal reflectivity profiles were generated and compared with healthy controls., Results: Twelve patients (18.2%) had a retinal sheen on color images that cosegregated with an abnormally broad hyper-reflective ellipsoid zone band on OCT imaging. Three-fourths of these patients were male, had a cone-rod dystrophy, and had pathogenic RPGR variants located toward the 3'-end of ORF15. This group had a different longitudinal reflectivity profile signature compared with controls. After a period of prolonged dark adaptation, the abnormal hyper-reflective band on OCT became less apparent, and the outer retinal layers adopted a more normal appearance., Conclusions: RPGR-related retinopathy should be considered for males presenting with retinal sheen, abnormal ellipsoid zone hyper-reflectivity, and cone or cone-rod dysfunction on ERG, and pursued with molecular testing. Our results have implications for understanding the role of the C-terminal domain encoded by RPGR ORF15 in the phototransduction cascade. Further, the findings may be important to incorporate into both inclusion criteria and outcome measure developments in future RPGR-related cone or cone-rod dystrophy clinical trials.

Hereditary deafness and retinal dystrophy are each genetically heterogenous and clinically variable. Three small unrelated families segregating the combination of deafness and retinal dystrophy were studied by exome sequencing (ES). The proband of Family 1 was found to be compound heterozygous for NM&#95;004525.3: LRP2: c.5005A > G, p.(Asn1669Asp) and c.149C > G, p.(Thr50Ser). In Family 2, two sisters were found to be compound heterozygous for LRP2 variants, p.(Tyr3933Cys) and an experimentally confirmed c.7715 + 3A > T consensus splice-altering variant. In Family 3, the proband is compound heterozygous for a consensus donor splice site variant LRP2: c.8452&#95;8452 + 1del and p.(Cys3150Tyr). In mouse cochlea, Lrp2 is expressed abundantly in the stria vascularis marginal cells demonstrated by smFISH, single-cell and single-nucleus RNAseq, suggesting that a deficiency of LRP2 may compromise the endocochlear potential, which is required for hearing. LRP2 variants have been associated with Donnai-Barrow syndrome and other multisystem pleiotropic phenotypes different from the phenotypes of the four cases reported herein. Our data expand the phenotypic spectrum associated with pathogenic variants in LRP2 warranting their consideration in individuals with a combination of hereditary hearing loss and retinal dystrophy., (© 2023 John Wiley & Sons Ltd. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.)

Boucher-Neuhäuser syndrome (BNHS) is characterized by chorioretinal dystrophy, hypogonadotropic hypogonadism, and cerebellar dysfunction and atrophy. The disorder has been associated with biallelic pathogenic variants in the patatin-like phospholipase domain-containing protein 6 (PNPLA6) gene. We present an individual with a clinical diagnosis consistent with BNHS who lacked any PNPLA6 variants but on quartet family exome sequencing had a de novo variant in the hexokinase 1 (HK1) gene (NM&#95;000188.2 [GRCh37/hg19]: g.71139826G>A, c.1240G>A, p.Gly414Arg), suggesting genetic heterogeneity for BNHS. Longitudinal follow-up indicated neurological deterioration, neuropsychiatric symptoms, and progressive cerebellar atrophy. The BNHS phenotype overlaps and expands the known HK1 genotypic and phenotypic spectrum. Individuals with variants in HK1 should undergo evaluation for hypogonadotropic hypogonadism, potentially amenable to treatment., (© 2022 Wiley Periodicals LLC. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.)

Stargardt disease (STGD1) is the most common inherited retina degeneration. It is caused by biallelic ABCA4 variants, and no treatment is available to date. STGD1 shows marked phenotypic variability, especially regarding the age of onset. The underlying genotype can partially explain this variability. Notably, a subset of ABCA4 variants was previously associated with an earlier disease onset than truncating ABCA4 variants, pointing toward pathogenic mechanisms beyond the loss of gene function in these patients. On the other end of the spectrum, variants such as p.Gly1961Glu were associated with markedly slower extrafoveal disease progression. Given that these drastic differences in phenotype are based on genotype (resulting in important prognostic implications for patients), this chapter reviews previous approaches to genotype-phenotype correlation analyses in STGD1., (© 2023. The Author(s), under exclusive license to Springer Nature Switzerland AG.)

Mutations in the IQ calmodulin-binding motif containing B1 (IQCB1)/NPHP5 gene encoding the ciliary protein nephrocystin 5 cause early-onset blinding disease Leber congenital amaurosis (LCA), together with kidney dysfunction in Senior-Løken syndrome. For in vitro disease modeling, we obtained dermal fibroblasts from patients with NPHP5-LCA that were reprogrammed into induced pluripotent stem cells (iPSCs) and differentiated into retinal pigment epithelium (RPE) and retinal organoids. Patient fibroblasts and RPE demonstrated aberrantly elongated ciliary axonemes. Organoids revealed impaired development of outer segment structures, which are modified primary cilia, and mislocalization of visual pigments to photoreceptor cell soma. All patient-derived cells showed reduced levels of CEP290 protein, a critical cilia transition zone component interacting with NPHP5, providing a plausible mechanism for aberrant ciliary gating and cargo transport. Disease phenotype in NPHP5-LCA retinal organoids could be rescued by adeno-associated virus (AAV)-mediated IQCB1/NPHP5 gene augmentation therapy. Our studies thus establish a human disease model and a path for treatment of NPHP5-LCA., Competing Interests: Declaration of interests The authors declare no competing interests., (Published by Elsevier Inc.)

Objectives: To test the hypothesis that ROSAH (retinal dystrophy, optic nerve oedema, splenomegaly, anhidrosis and headache) syndrome, caused by dominant mutation in ALPK1 , is an autoinflammatory disease., Methods: This cohort study systematically evaluated 27 patients with ROSAH syndrome for inflammatory features and investigated the effect of ALPK1 mutations on immune signalling. Clinical, immunologic and radiographical examinations were performed, and 10 patients were empirically initiated on anticytokine therapy and monitored. Exome sequencing was used to identify a new pathogenic variant. Cytokine profiling, transcriptomics, immunoblotting and knock-in mice were used to assess the impact of ALPK1 mutations on protein function and immune signalling., Results: The majority of the cohort carried the p.Thr237Met mutation but we also identified a new ROSAH-associated mutation, p.Tyr254Cys.Nearly all patients exhibited at least one feature consistent with inflammation including recurrent fever, headaches with meningeal enhancement and premature basal ganglia/brainstem mineralisation on MRI, deforming arthritis and AA amyloidosis. However, there was significant phenotypic variation, even within families and some adults lacked functional visual deficits. While anti-TNF and anti-IL-1 therapies suppressed systemic inflammation and improved quality of life, anti-IL-6 (tocilizumab) was the only anticytokine therapy that improved intraocular inflammation (two of two patients).Patients' primary samples and in vitro assays with mutated ALPK1 constructs showed immune activation with increased NF-κB signalling, STAT1 phosphorylation and interferon gene expression signature. Knock-in mice with the Alpk1 T237M mutation exhibited subclinical inflammation.Clinical features not conventionally attributed to inflammation were also common in the cohort and included short dental roots, enamel defects and decreased salivary flow., Conclusion: ROSAH syndrome is an autoinflammatory disease caused by gain-of-function mutations in ALPK1 and some features of disease are amenable to immunomodulatory therapy., Competing Interests: Competing interests: FS is a cofounder and stockholder of Pyrotech therapeutics, a company that aims to develop agonist/inhibitor drugs for ALPK1. RM has received honorary fees for lectures from SHIRE-TAKEDA- SANOFI- NOVARTIS-SOBI and Nida Sen is employed by Janssen., (© Author(s) (or their employer(s)) 2022. Re-use permitted under CC BY. Published by BMJ.)

Purpose: To describe the relationships between foveal structure and visual function in a cohort of individuals with foveal hypoplasia (FH) and to estimate FH grade and visual acuity using a deep learning classifier., Design: Retrospective cohort study and experimental study., Participants: A total of 201 patients with FH were evaluated at the National Eye Institute from 2004 to 2018., Methods: Structural components of foveal OCT scans and corresponding clinical data were analyzed to assess their contributions to visual acuity. To automate FH scoring and visual acuity correlations, we evaluated the following 3 inputs for training a neural network predictor: (1) OCT scans, (2) OCT scans and metadata, and (3) real OCT scans and fake OCT scans created from a generative adversarial network., Main Outcome Measures: The relationships between visual acuity outcomes and determinants, such as foveal morphology, nystagmus, and refractive error., Results: The mean subject age was 24.4 years (range, 1-73 years; standard deviation = 18.25 years) at the time of OCT imaging. The mean best-corrected visual acuity (n = 398 eyes) was equivalent to a logarithm of the minimal angle of resolution (LogMAR) value of 0.75 (Snellen 20/115). Spherical equivalent refractive error (SER) ranged from -20.25 diopters (D) to +13.63 D with a median of +0.50 D. The presence of nystagmus and a high-LogMAR value showed a statistically significant relationship ( P < 0.0001). The participants whose SER values were farther from plano demonstrated higher LogMAR values (n = 382 eyes). The proportion of patients with nystagmus increased with a higher FH grade. Variability in SER with grade 4 (range, -20.25 D to +13.00 D) compared with grade 1 (range, -8.88 D to +8.50 D) was statistically significant ( P < 0.0001). Our neural network predictors reliably estimated the FH grading and visual acuity (correlation to true value > 0.85 and > 0.70, respectively) for a test cohort of 37 individuals (98 OCT scans). Training the predictor on real OCT scans with metadata and fake OCT scans improved the accuracy over the model trained on real OCT scans alone., Conclusions: Nystagmus and foveal anatomy impact visual outcomes in patients with FH, and computational algorithms reliably estimate FH grading and visual acuity.

Choroideremia is an X-linked, blinding retinal degeneration with progressive loss of photoreceptors, retinal pigment epithelial (RPE) cells, and choriocapillaris. To study the extent to which these layers are disrupted in affected males and female carriers, we performed multimodal adaptive optics imaging to better visualize the in vivo pathogenesis of choroideremia in the living human eye. We demonstrate the presence of subclinical, widespread enlarged RPE cells present in all subjects imaged. In the fovea, the last area to be affected in choroideremia, we found greater disruption to the RPE than to either the photoreceptor or choriocapillaris layers. The unexpected finding of patches of photoreceptors that were fluorescently-labeled, but structurally and functionally normal, suggests that the RPE blood barrier function may be altered in choroideremia. Finally, we introduce a strategy for detecting enlarged cells using conventional ophthalmic imaging instrumentation. These findings establish that there is subclinical polymegathism of RPE cells in choroideremia., (© 2022. This is a U.S. Government work and not under copyright protection in the US; foreign copyright protection may apply.)

Purpose: To assess the structure of cone photoreceptors and retinal pigment epithelial (RPE) cells in vitelliform macular dystrophy (VMD) arising from various genetic etiologies., Methods: Multimodal adaptive optics (AO) imaging was performed in 11 patients with VMD using a custom-assembled instrument. Non-confocal split detection and AO-enhanced indocyanine green were used to visualize the cone photoreceptor and RPE mosaics, respectively. Cone and RPE densities were measured and compared across BEST1-, PRPH2-, IMPG1-, and IMPG2-related VMD., Results: Within macular lesions associated with VMD, both cone and RPE densities were reduced below normal, to 37% of normal cone density (eccentricity 0.2 mm) and to 8.4% of normal RPE density (eccentricity 0.5 mm). Outside of lesions, cone and RPE densities were slightly reduced (both to 92% of normal values), but with high degree of variability in the individual measurements. Comparison of juxtalesional cone and RPE measurements (<1 mm from the lesion edge) revealed significant differences in RPE density across the four genes (P < 0.05). Overall, cones were affected to a greater extent than RPE in patients with IMPG1 and IMPG2 pathogenic variants, but RPE was affected more than cones in BEST1 and PRPH2 VMD. This trend was observed even in contralateral eyes from a subset of five patients who presented with macular lesions in only one eye., Conclusions: Assessment of cones and RPE in retinal locations outside of the macular lesions reveals a pattern of cone and RPE disruption that appears to be gene dependent in VMD. These findings provide insight into the cellular pathogenesis of disease in VMD.

Purpose: The effect of noncoding variants is often unknown in the absence of functional assays. Here, we characterized an ABCA4 intron 7 variant, c.859-25A>G, identified in Palestinian probands with Stargardt disease (STGD) or cone-rod dystrophy (CRD). We investigated the effect of this variant on the ABCA4 mRNA and retinal phenotype, and its prevalence in Palestine., Methods: The ABCA4 gene was sequenced completely or partially in 1998 cases with STGD or CRD. The effect of c.859-25A>G on splicing was investigated in silico using SpliceAI and in vitro using splice assays. Homozygosity mapping was performed for 16 affected individuals homozygous for c.859-25A>G. The clinical phenotype was assessed using functional and structural analyses including visual acuity, full-field electroretinography, and multimodal imaging., Results: The smMIPs-based ABCA4 sequencing revealed c.859-25A>G in 10 Palestinian probands from Hebron and Jerusalem. SpliceAI predicted a significant effect of this putative branchpoint-inactivating variant on the nearby intron 7 splice acceptor site. Splice assays revealed exon 8 skipping and two partial inclusions of intron 7, each having a deleterious effect. Additional genotyping revealed another 46 affected homozygous or compound heterozygous individuals carrying variant c.859-25A>G. Homozygotes shared a genomic segment of 59.6 to 87.9 kb and showed severe retinal defects on ophthalmoscopic evaluation., Conclusions: The ABCA4 variant c.859-25A>G disrupts a predicted branchpoint, resulting in protein truncation because of different splice defects, and is associated with early-onset STGD1 when present in homozygosity. This variant was found in 25/525 Palestinian inherited retinal dystrophy probands, representing one of the most frequent inherited retinal disease-causing variants in West-Bank Palestine.

Joubert syndrome (JS) is a neurodevelopmental disorder characterized by hypotonia and developmental delay, as well as the obligatory molar tooth sign on brain imaging. Since hypotonia and developmental delay are nonspecific features, there must be a high level of clinical suspicion of JS so that the diagnostic brain imaging and/or molecular testing for the >38 genes associated with JS is/are obtained. The goal of this study was to analyze clinical photographs of a cohort of patients with JS to define a list of physical examination features that should prompt investigation for JS. Analysis of photographs from 94 individuals with JS revealed that there is a recognizable pattern of facial features in JS that changes over time as individuals age. Macrocephaly, head tilting even when looking straight ahead, eye movement abnormalities (oculomotor apraxia, nystagmus, strabismus), and ptosis are common in those with JS. Distinctive features in younger children include triangular-shaped open mouth with tongue protrusion; in older children and adults, mandibular prognathia and prominent nasal bridge are common., (© 2022 Wiley Periodicals LLC. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.)

BACKGROUNDOutcome measures sensitive to disease progression are needed for ATP-binding cassette, sub-family A, member 4-associated (ABCA4-associated) retinopathy. We aimed to quantify ellipsoid zone (EZ) loss and photoreceptor degeneration beyond EZ-loss in ABCA4-associated retinopathy and investigate associations between photoreceptor degeneration, genotype, and age.METHODSWe analyzed 132 eyes from 66 patients (of 67 enrolled) with molecularly confirmed ABCA4-associated retinopathy from a prospective natural history study with a median [IQR] follow-up of 4.2 years [3.1, 5.1]. Longitudinal spectral-domain optical coherence tomography volume scans (37 B-scans, 30° × 15°) were segmented using a deep learning (DL) approach. For genotype-phenotype analysis, a model of ABCA4 variants was applied with the age of criterion EZ-loss (6.25 mm2) as the dependent variable.RESULTSPatients exhibited an average (square-root-transformed) EZ-loss progression rate of [95% CI] 0.09 mm/y [0.06, 0.11]. Outer nuclear layer (ONL) thinning extended beyond the area of EZ-loss. The average distance from the EZ-loss boundary to normalization of ONL thickness (to ±2 z score units) was 3.20° [2.53, 3.87]. Inner segment (IS) and outer segment (OS) thinning was less pronounced, with an average distance from the EZ-loss boundary to layer thickness normalization of 1.20° [0.91, 1.48] for the IS and 0.60° [0.49, 0.72] for the OS. An additive model of allele severity explained 52.7% of variability in the age of criterion EZ-loss.CONCLUSIONPatients with ABCA4-associated retinopathy exhibited significant alterations of photoreceptors outside of EZ-loss. DL-based analysis of photoreceptor laminae may help monitor disease progression and estimate the severity of ABCA4 variants.TRIAL REGISTRATIONClinicalTrials.gov identifier: NCT01736293.FUNDINGNational Eye Institute Intramural Research Program and German Research Foundation grant PF950/1-1.

Sensorineural hearing loss (SNHL) is characteristic of Usher syndrome type 2 (USH2), but less is known about SNHL in nonsyndromic autosomal recessive retinitis pigmentosa (ARRP) and olfaction in USH2A-associated retinal degeneration. The Rate of Progression of USH2A-related Retinal Degeneration (RUSH2A) is a natural history study that enrolled 127 participants, 80 with USH2 and 47 with ARRP. Hearing was measured by pure-tone thresholds and word recognition scores, and olfaction by the University of Pennsylvania Smell Identification Test (UPSIT). SNHL was moderate in 72% of USH2 participants and severe or profound in 25%, while 9% of ARRP participants had moderate adult-onset SNHL. Pure-tone thresholds worsened with age in ARRP but not in USH2 participants. The degree of SNHL was not associated with other participant characteristics in either USH2 or ARRP. Median pure-tone thresholds in ARRP participants were significantly higher than the normative population (p < 0.001). Among 14 USH2 participants reporting newborn hearing screening results, 7 reported passing. Among RUSH2A participants, 7% had mild microsmia and 5% had moderate or severe microsmia. Their mean (±SD) UPSIT score was 35 (±3), similar to healthy controls (34 [±3]; p = 0.39). Olfaction differed by country (p = 0.02), but was not significantly associated with clinical diagnosis, age, gender, race/ethnicity, smoking status, visual measures, or hearing. Hearing loss in USH2A-related USH2 did not progress with age. ARRP patients had higher pure-tone thresholds than normal. Newborn hearing screening did not identify all USH2A-related hearing loss. Olfaction was not significantly worse than normal in participants with USH2A-related retinal degeneration., (© 2021 Wiley Periodicals LLC.)

Usher syndrome type I (USH1) is characterized by deafness, vestibular areflexia, and progressive retinal degeneration. The protein-truncating p.Arg245* founder variant of PCDH15 (USH1F) has an ~2% carrier frequency amongst Ashkenazi Jews accounts for ~60% of their USH1 cases. Here, longitudinal phenotyping in 13 USH1F individuals revealed progressive retinal degeneration, leading to severe vision loss with macular atrophy by the sixth decade. Half of the affected individuals were legally blind by their mid-50s. The mouse Pcdh15 R250X variant is equivalent to human p.Arg245*. Homozygous Pcdh15 R250X mice also have visual deficits and aberrant light-dependent translocation of the phototransduction cascade proteins, arrestin, and transducin. Retinal pigment epithelium (RPE)-specific retinoid cycle proteins, RPE65 and CRALBP, were also reduced in Pcdh15 R250X mice, indicating a dual role for protocadherin-15 in photoreceptors and RPE. Exogenous 9- cis retinal improved ERG amplitudes in Pcdh15 R250X mice, suggesting a basis for a clinical trial of FDA-approved retinoids to preserve vision in USH1F patients., Competing Interests: SS, WZ, SR, AG, TD, RH, CB, AG, TR, SR, TF, ZA No competing interests declared, JS Julie M. Schultz is affiliated with GeneDx, Inc. The author has no financial interests to declare.

Purpose: To conduct a proof-of-principle study to identify subtypes of propionic acidemia (PA) and associated biomarkers., Methods: Data from a clinically diverse PA patient population ( https://clinicaltrials.gov/ct2/show/NCT02890342 ) were used to train and test machine learning models, identify PA-relevant biomarkers, and perform validation analysis using data from liver-transplanted participants. k-Means clustering was used to test for the existence of PA subtypes. Expert knowledge was used to define PA subtypes (mild and severe). Given expert classification, supervised machine learning (support vector machine with a polynomial kernel, svmPoly) performed dimensional reduction to define relevant features of each PA subtype., Results: Forty participants enrolled in the study; five underwent liver transplant. Analysis with k-means clustering indicated that several PA subtypes may exist on the biochemical continuum. The conventional PA biomarkers, plasma total 2-methylctirate and propionylcarnitine, were not statistically significantly different between nontransplanted and transplanted participants motivating us to search for other biomarkers. Unbiased dimensional reduction using svmPoly revealed that plasma transthyretin, alanine:serine ratio, GDF15, FGF21, and in vivo 1- 13 C-propionate oxidation, play roles in defining PA subtypes., Conclusion: Support vector machine prioritized biomarkers that helped classify propionic acidemia patients according to severity subtypes, with important ramifications for future clinical trials and management of PA., (© 2021. This is a U.S. government work and not under copyright protection in the U.S.; foreign copyright protection may apply.)