A Comprehensive Report of Intrinsically Disordered Regions in Inherited Retinal Diseases.

BACKGROUND/PURPOSE: A comprehensive review of the degree of disorder in all genes in the Retinal Information Network (RetNet) Database is implicated in inherited retinal diseases (IRDs). Their association with a missense variation was evaluated. METHODS: IRD genes from RetNet were included in this study. Publicly available data on the genome aggregation database (gnomAD) were used to analyze the number of total and pathogenic missense variants. Metapredict, an accurate and high-performance predictor that reproduces consensus disorder scores, was used to calculate disorder. MAIN OUTCOME MEASURES: The main outcome measures were percent disorder, percent pathogenicity, number of total missense variants, and percent total missense variation. RESULTS: We included 287 RetNet genes with relevant data available from gnomAD. Mean percent disorder was 26.3% ± 26.0%, mean percent pathogenicity was 5.2% ± 11.0%, mean number of total missense variants was 424.4 ± 450.0, and mean percent total missense was 50.0% ± 13.4%. The percent disorder followed a bimodal distribution with the highest number of occurrences in the 0 to 10th disorder decile. The five outlier proteins in the first disorder decile with a higher-than-expected number of total missense variation were identified (HMCN1, ADGRV, USH2A, DYNC2H1, LAMA1, and SLC38A8). When excluded, % total missense was significantly associated with percent disorder (R = 0.238 and p = 0.0240). CONCLUSIONS: This novel study examining all genes implicated in IRDs found that the majority genes had a disorder in the 0 to 10th decile and were relatively intolerant to missense variation. This may have future utility when interpreting variants of undetermined significance and missense variants.

Molecular and Clinical Characterization of CNGA3 and CNGB3 Genes in Brazilian Patients Affected with Achromatopsia.

Achromatopsia (ACHM) is a congenital cone photoreceptor disorder characterized by reduced visual acuity, nystagmus, photophobia, and very poor or absent color vision. Pathogenic variants in six genes encoding proteins composing the cone phototransduction cascade (CNGA3, CNGB3, PDE6C, PDE6H, GNAT2) and of the unfolded protein response (ATF6) have been related to ACHM cases, while CNGA3 and CNGB3 alone are responsible for most cases. Herein, we provide a clinical and molecular overview of 42 Brazilian patients from 38 families affected with ACHM related to biallelic pathogenic variants in the CNGA3 and CNGB3 genes. Patients' genotype and phenotype were retrospectively evaluated. The majority of CNGA3 variants were missense, and the most prevalent CNGB3 variant was c.1148delC (p.Thr383Ilefs*13), resulting in a frameshift and premature stop codon, which is compatible with previous publications in the literature. A novel variant c.1893T>A (p.Tyr631*) in the CNGB3 gene is reported for the first time in this study. A great variability in morphologic findings was observed in our patients, although no consistent correlation with age and disease stage in OCT foveal morphology was found. The better understanding of the genetic variants landscape in the Brazilian population will help in the diagnosis of this disease.

A DOUBLE HYPERAUTOFLUORESCENT RING IN A 33-YEAR-OLD-FEMALE PATIENT.

PURPOSE: To describe the clinical phenotype and molecular diagnosis of a patient with atypical presentation of enhanced S-cone syndrome. METHODS: This is a case report of a patient who underwent best-corrected visual acuity, slit-lamp exam, fundus examination, autofluorescence, optical coherence tomography, kinetic perimetry, and full-field electroretinography. Genetic testing was performed via next-generation sequencing. RESULTS: A 33-year-old female patient presented with mild nyctalopia, but normal rod function measured by electroretinogram and foveoschisis on optical coherence tomography. She also presented a double hyperautofluorescent ring on autofluorescence. Genetic testing found a pathogenic variant c.925C>G (p.Arg309Gly) and a likely pathogenic variant c.299C>T (p.Arg77Trp) in NR2E3 gene. CONCLUSION: Enhanced S-cone syndrome may present without the pathognomonic findings of decreased rod function on electroretinogram, suggesting the importance of genetic testing in retinal diseases for diagnosis.