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Abstract Background This report presents a clinical case of syndromic rod-cone dystrophy due to a splice site variant in the ARL2BP gene causing situs inversus, asthenozoospermia, unilateral renal agenesis and microcysts. The presence of renal agenesis and cryptorchidism expands the clinical manifestations due to ARL2BP variants. The detailed, long-term follow-up contributes valuable insights into disease progression, aiding clinical diagnosis and patient management. Case Presentation The male patient complained of photophobia as the first symptom when he was 20 years old followed by nyctalopia, loss of central visual acuity and peripheral visual field ten years later. Genetic analysis identified a likely pathogenic homozygous variant (c.294-1G > C) involving the splicing acceptor site of intron 4. Reported symptoms together with full-field stimulus threshold testing, electroretinogram and advanced multimodal imaging allowed us to recognize the typical characteristics of a mixed retinal dystrophy. Despite the end-stage retinal disease, this patient still retained a useful residual vision at 63 years and had a slow disease progression during the last 5 years of evaluation. Discussion and conclusions Our findings underscore the variable clinical presentation of ARL2BP variants, emphasizing the importance of a nuanced approach in diagnosing and managing patients. The presence of renal cysts warrants consideration of a differential diagnosis, particularly with Senior-Loken (SLS), Bardet-Biedl (BBS) and Joubert syndromes (JS) but also with Short Rib Thoracic Dysplasia 9, highlighting the need for careful phenotypic evaluation in these cases.

Abstract Background Non-syndromic inherited retinal dystrophies (IRDs) such as retinitis pigmentosa or Leber congenital amaurosis generally manifest between early childhood and late adolescence, imposing profound long-term impacts as a result of vision impairment or blindness. IRDs are highly heterogeneous, with often overlapping symptoms among different IRDs, and achieving a definite diagnosis is challenging. This narrative review provides a clinical overview of the non-syndromic generalized photoreceptor dystrophies, particularly retinitis pigmentosa and Leber congenital amaurosis. The clinical investigations and genetic testing needed to establish a diagnosis are outlined, and current management approaches are discussed, focusing on the importance of the involvement of an interdisciplinary team from diagnosis and initial care to long-term follow-up and support. Results The effective management of IRDs requires a multidisciplinary, and ideally interdisciplinary, team of experts knowledgeable about IRDs, with experienced professionals from fields as diverse as ophthalmology, neuropsychiatry, psychology, neurology, genetics, orthoptics, developmental therapy, typhlology, occupational therapy, otolaryngology, and orientation and mobility specialties. Accurate clinical diagnosis encompasses a range of objective and subjective assessments as a prerequisite for the genetic testing essential in establishing an accurate diagnosis necessary for the effective management of IRDs, particularly in the era of gene therapies. Improvements in genome sequencing techniques, such as next-generation sequencing, have greatly facilitated the complex process of determining IRD-causing gene variants and establishing a molecular diagnosis. Genetic counseling is essential to help the individual and their family understand the condition, the potential risk for offspring, and the implications of a diagnosis on visual prognosis and treatment options. Psychological support for patients and caregivers is important at all stages of diagnosis, care, and rehabilitation and is an essential part of the multidisciplinary approach to managing IRDs. Effective communication throughout is essential, and the patient and caregivers’ needs and expectations must be acknowledged and discussed. Conclusion As IRDs can present at an early age, clinicians need to be aware of the clinical signs suggesting visual impairment and follow up with multidisciplinary support for timely diagnoses to facilitate appropriate therapeutic or rehabilitation intervention to minimize vision loss.

Abstract Background Best vitelliform macular dystrophy (BVMD) is an autosomal dominant macular degeneration. The typical central yellowish yolk-like lesion usually appears in childhood and gradually worsens. Most cases are caused by variants in the BEST1 gene which encodes bestrophin-1, an integral membrane protein found primarily in the retinal pigment epithelium. Methods Here we describe the spectrum of BEST1 variants identified in a cohort of 57 Italian patients analyzed by Sanger sequencing. In 13 cases, the study also included segregation analysis in affected and unaffected relatives. We used molecular mechanics to calculate two quantitative parameters related to calcium-activated chloride channel (CaCC composed of 5 BEST1 subunits) stability and calcium-dependent activation and related them to the potential pathogenicity of individual missense variants detected in the probands. Results Thirty-six out of 57 probands (63% positivity) and 16 out of 18 relatives proved positive to genetic testing. Family study confirmed the variable penetrance and expressivity of the disease. Six of the 27 genetic variants discovered were novel: p.(Val9Gly), p.(Ser108Arg), p.(Asn179Asp), p.(Trp182Arg), p.(Glu292Gln) and p.(Asn296Lys). All BEST1 variants were assessed in silico for potential pathogenicity. Our computational structural biology approach based on 3D model structure of the CaCC showed that individual amino acid replacements may affect channel shape, stability, activation, gating, selectivity and throughput, and possibly also other features, depending on where the individual mutated amino acid residues are located in the tertiary structure of BEST1. Statistically significant correlations between mean logMAR best-corrected visual acuity (BCVA), age and modulus of computed BEST1 dimerization energies, which reflect variations in the in CaCC stability due to amino acid changes, permitted us to assess the pathogenicity of individual BEST1 variants. Conclusions Using this computational approach, we designed a method for estimating BCVA progression in patients with BEST1 variants.

Abstract Background Bardet–Biedl syndrome (BBS) is a rare inherited multisystemic disorder with autosomal recessive or complex digenic triallelic inheritance. There is currently no treatment for BBS, but some morbidities can be managed. Accurate molecular diagnosis is often crucial for the definition of appropriate patient management and for the development of a potential personalized therapy. Methods We developed a next-generation-sequencing (NGS) protocol for the screening of the 18 most frequently mutated genes to define the genotype and clarify the mutation spectrum of a cohort of 20 BBS Italian patients. Results We defined the causative variants in 60% of patients; four of those are novel. 33% of patients also harboured variants in additional gene/s, suggesting possible oligogenic inheritance. To explore the function of different genes, we looked for correlations between genotype and phenotype in our cohort. Hypogonadism was more frequently detected in patients with variants in BBSome proteins, while renal abnormalities in patients with variations in BBSome chaperonin genes. Conclusions NGS is a powerful tool that can help understanding BBS patients’ phenotype through the identification of mutations that could explain differences in phenotype severity and could provide insights for the development of targeted therapy. Furthermore, our results support the existence of additional BBS loci yet to be identified.

Abstract Background Based on phenotypic similarities between age-related macular degeneration and the autosomal disorder Doyne honeycomb retinal dystrophy, we report on a single nanolaser treatment of a patient with genotype Doyne honeycomb retinal dystrophy confirmation and evidence of disease progression over 12 months. The case study is the first report of short-term results of subthreshold nanolaser treatment in a patient with Doyne honeycomb retinal dystrophy. Case presentation A 43-year-old Caucasian man with moderate loss of visual acuity in his left eye (20/40) and normal visual acuity in his right eye (20/20), with clinical Doyne honeycomb retinal dystrophy diagnosis and genetic confirmation of the common heterozygous mutation (EFEMP1) by genetic testing, underwent nanopulse subthreshold laser treatment in his left eye. A safety examination, carried out 7 days after treatment, and clinical follow-up, conducted 60 days following laser treatment, showed improvement of visual acuity from baseline by two letters and a subjective improvement of blurring. While no apparent morphological changes were found on fundoscopy, increased autofluorescence in the treated eye was observed on imaging. In addition, 2 months after nanopulse subthreshold laser treatment, rod-mediated and cone-mediated full-field electroretinography b-wave amplitudes showed an increase from baseline in both the treated eye (300%) and untreated eye (50%). At 2 months after nanopulse subthreshold laser treatment, multifocal electroretinograms showed improvement. Acuity and full-field electroretinography improvement persisted at 6-month follow-up. Conclusions Sustained improvements in retinal function on electroretinography persisted in both eyes 6 months after treatment, suggesting an enhancement of phototransduction and retinoid recycling induced by nanopulse subthreshold laser treatment. The functional improvement observed in the untreated eye is hypothesized to arise from an increased expression and release of metalloproteinases that circulate systemically.

Abstract Background Enhanced S-cone syndrome is an autosomal recessive retinal dystrophy related to a defect in a nuclear receptor gene (NR2E3) that leads to alteration in cells development from rod to S-cone. This retinal dystrophy may be associated with retinal schisis. The aim of this report is to describe structural optical coherence tomography and optical coherence tomography angiography features in a case of enhanced S-cone syndrome associated with macular schisis. Case presentation A Caucasian 13-year-old girl underwent measurement of best corrected visual acuity, ophthalmoscopic evaluation, and fundus autofluorescence examination. Photopic and scotopic electroretinography were carried out as well. Enhanced S-cone syndrome was suspected on the basis of clinical and electrophysiological findings. Structural optical coherence tomography and optical coherence tomography angiography allowed the further characterization of the associated macular schisis. Genetic analysis not only confirmed the diagnosis but increased the clinical novelty of this case report by showing two variations in the NR2E3 gene probably related to the phenotype: a missense variation c.1118T>C which leads to the substitution of leucine with proline in amino acid position 373, and c.349+5G>C, which involves a gene sequence near a splicing site. Conclusions Swept source structural optical coherence tomography (B scans and “en face” images) and optical coherence tomography angiography allowed the observation of retinal structural details and the involvement of each retinal layer and capillary plexus in enhanced S-cone syndrome. Of interest, neither of the two NR2E3 gene variants found in this case report have been linked to any form of retinopathy.