Aim To investigate the prevalence of macular abnormalities in a large Caucasian cohort of patients affected by retinitis pigmentosa (RP). Methods A retrospective study was performed by reviewing the medical records and optical coherence tomography (OCT) scans in a cohort of 581 RP patients in order to assess the presence of macular abnormalities —that is, cystoid macular oedema (CMO), epiretinal membrane (ERM), vitreo-macular traction syndrome, and macular hole. Results Macular abnormalities were observed in 524 (45.1%) out of the 1161 examined eyes. The most frequent abnormality was CMO, observed in 237 eyes (20.4%) from 133 patients (22.9%), followed by ERM, assessed in 181 eyes (15.6%) from 115 patients (19.8%). Moreover, vitreo-retinal abnormalities were significantly (p<0.05) associated with older age, cataract surgery, or cataract. CMO appeared to be significantly (p<0.05) associated with female gender, autosomic dominant inheritance pattern, and cataract. Conclusions Macular abnormalities are more frequent in RP compared to the general population. For that reason, screening RP patients with OCT is highly recommended to follow-up the patients, evaluate the natural history of disease, and identify those patients who could benefit from current or innovative therapeutic strategies.

Purpose.: The purpose of this study was to identify the molecular basis of albinism in a large cohort of Italian patients showing typical ocular landmarks of the disease and to provide a full characterization of the clinical ophthalmic manifestations. Methods.: DNA samples from 45 patients with ocular manifestations of albinism were analyzed by direct sequencing analysis of five genes responsible for albinism: TYR, P, TYRP1, SLC45A2 (MATP), and OA1. All patients studied showed a variable degree of skin and hair hypopigmentation. Eighteen patients with distinct mutations in each gene associated with OCA were evaluated by detailed ophthalmic analysis, optical coherence tomography (OCT), and fundus autofluorescence. Results.: Disease-causing mutations were identified in more than 95% of analyzed patients with OCA (28/45 [62.2%] cases with two or more mutations; 15/45 [33.3%] cases with one mutation). Thirty-five different mutant alleles were identified of which 15 were novel. Mutations in TYR were the most frequent (73.3%), whereas mutations in P occurred more rarely (13.3%) than previously reported. Novel mutations were also identified in rare loci such as TYRP1 and MATP. Mutations in the OA1 gene were not detected. Clinical assessment revealed that patients with iris and macular pigmentation had significantly higher visual acuity than did severe hypopigmented phenotypes. Conclusions.: TYR gene mutations represent a relevant cause of oculocutaneous albinism in Italy, whereas mutations in P present a lower frequency than that found in other populations. Clinical analysis revealed that the severity of the ocular manifestations depends on the degree of retinal pigmentation.

Bardet-Biedl syndrome (BBS) is a rare genetic disorder that features retinal degeneration, obesity, polydactyly, learning disabilities and renal abnormalities. The diagnosis is often missed at birth, the median age at diagnosis being 9 years. In the attempt to shed light on BBS and improve its diagnosis and treatment, we evaluated the genotype-phenotype relationship in patients with a molecular diagnosis of BBS. We analyzed three common BBS genes, BBS1, BBS10 and BBS2, in 25 Italian patients fulfilling the clinical criteria of BBS. In 12 patients, we identified gene-specific biallelic variants and thus correlated genotype to the ophthalmic, renal and audio-vestibular phenotypes. At least one sequence variant was found in 60% of patients. The most common mutated gene was BBS1 followed by BBS10. Of the 17 sequence variants we found, 11 have not previously been associated with BBS. In 12 patients, we identified biallelic pathogenic variants; they had retinitis pigmentosa with early onset of visual impairment. However, retinal dystrophy was less severe in patients with BBS1 than in those with BBS10 variants. Overall, we found a high prevalence of renal dysmorphism and dysfunction. Notably, patients with BBS10 variants had the most severe renal impairment, which resulted in a critical decline in renal function. All the patients who underwent audio-vestibular evaluation had dysfunction of the cochlear outer hair cells, thus confirming the presence of hearing defects. BBS1, BBS2 and BBS10 are major causative genes in Italian BBS patients. BBS10 was associated with the worse outcome in terms of the renal, ocular and audiovestibular phenotypes. Cochlear dysfunction should be included among the hallmarks of BBS.

Purpose.: To perform a clinical characterization of Stargardt patients with ABCA4 gene mutation, and to investigate the correlation between the inner and outer segment (IS/OS) junction morphology and visual acuity, fundus lesions, electroretinogram abnormalities, and macular sensitivity. Methods.: Sixty-one patients with Stargardt disease (STGD) were given a comprehensive ophthalmic examination. Inner-outer photoreceptor junction morphology evaluated by spectral-domain optical coherence tomography was correlated with visual acuity, fundus lesions, fundus autofluorescence, full-field and multifocal electroretinography responses, and microperimetric macular sensitivities. We classified STGD patients into three groups: (1) IS/OS junction disorganization in the fovea, (2) IS/OS junction loss in the fovea, and (3) extensive loss of IS/OS junction. Mutation analysis of the ABCA4 gene was carried out by sequencing the complete coding region. Results.: A significant difference in visual acuity was observed between IS/OS groups 1 and 2 and between IS/OS groups 2 and 3 (P < 0.0001). A significant difference in microperimetry sensitivity was observed between IS/OS groups 2 and 3, and between IS/OS groups 1 and 3 (P < 0.0001). There was also a statistically significant correlation between IS/OS abnormalities and the extent of fundus lesions (Spearman P ≤ 0.01), as well as with the type of ERG and multifocal ERG results (Spearman P ≤ 0.01). Finally, the degree of IS/OS junction preservation showed a statistically significant correlation with the extension of foveal abnormalities assessed by fundus autofluorescence imaging (Spearman P ≤ 0.01). The G1961E mutation was more frequent in the patients without extensive loss of IS/OS junction (P = 0.01) confirming its association with a milder STGD phenotype. Conclusions.: The results of this study suggest that a comprehensive approach in the examination of Stargardt patients has the potential to improve the understanding of vision loss and may provide a sensitive measure to evaluate the efficacy of future experimental therapies in patients with STGD.

Purpose.: To evaluate the suitability of gene delivery-based approaches as potential treatment of Leber congenital amaurosis 4 (LCA4) due to AIPL1 mutations. Methods.: Genomic DNA from patients was analyzed using a microarray chip and direct sequencing. A detailed clinical evaluation including fundus autofluorescence (FAF) and optical coherence tomography (OCT) was performed in patients with AIPL1 mutations. Aipl1 null mice and porcine eyes were subretinally injected with adeno-associated viral (AAV) vectors harboring the human AIPL1 coding sequence. Results.: We identified 10 LCA4 patients with mutations in AIPL1. The p.W278X sequence variation was the one most frequently found. Clinical assessment revealed common features including diffuse retinal dystrophies and maculopathy. However, optical coherence tomography showed partially retained photoreceptors in extramacular regions at all ages. The fundus autofluorescence was elicitable at the posterior pole and absent in the fovea. AAV-mediated gene transfer in Aipl1 −/− mice was associated with restoration of AIPL1 and βPDE expression in photoreceptors and protection from degeneration. Administration of a clinically relevant dose of AAV2/8-AIPL1 to the preclinical large porcine retina resulted in high level of AIPL1 photoreceptor expression in the absence of toxicity. Conclusions.: Using advanced imaging diagnostics we showed that maculopathy is a main feature of LCA4. We identified retinal areas at the posterior pole with surviving photoreceptors present even in adult LCA4 patients, which could be the target of gene therapy. The possible use of gene therapy for LCA4 is additionally supported by the protection from photoreceptor degeneration observed in Aipl 1−/− mice and by the high levels of photoreceptor transduction in the absence of toxicity observed after AAV2/8 delivery to the large porcine retina.