A novel mutation GJA8 NM_005267.5: c.124G > A, p.(E42K) causing congenital nuclear cataract

Compound heterozygous mutations in GRM6 causing complete Schubert-Bornschein type congenital stationary night blindness

Background

To explore the genetic defects of a Chinese family with complete Schubert-Bornschein type congenital stationary night blindness (CSNB).

Methods

A Chinese family with complete Schubert-Bornschein type CSNB was enrolled in this study. The detailed ocular presentations of the patient were recorded. Targeted gene sequencing including 156 genes related to retinal diseases was used to detect the gene mutation. Sanger sequencing was performed to validate the potential pathogenic variants, and segregation analysis was performed on all available family members. Bioinformatics analysis was performed to predict the impact of the mutations.

Results

By targeted gene sequencing and Sanger sequencing, we identified compound heterozygous mutations in GRM6: c.152G>T (p.Gly51Val) and c.727delG (p.Val243SerfsX21). Segregation analysis demonstrated that the mother of the proband carried the missense mutation (c.152G>T) while her father carried the frameshift mutation (c.727delG), indicating CSNB was autosomal recessively inherited in this family. Several bioinformatics prediction programs revealed the mutations were "Damaging" or "Disease Causing" and conservation analysis showed both the codons Gly51 and Val243 were highly conserved among species, suggesting the changes were pathogenic.

Conclusion

By targeted gene sequencing and Sanger sequencing, we detected compound heterozygous mutations (c.152G>T, p.Gly51Val and c.727delG, p.Val243SerfsX21) in GRM6. The mutations co-segregated with the phenotype of the family members and are considered to be responsible for complete Schubert-Bornschein type CSNB. However, functional experiments in the future are needed to confirm the pathogenicity of the variants and to elucidate their exact molecular mechanisms causing CSNB.

Transcriptome alterations in sf3b4-depleted zebrafish: Insights into cataract formation in retinitis pigmentosa model

Posterior subcapsular cataract (PSC) frequently develops as a complication in patients with retinitis pigmentosa (RP). Despite numerous scientific investigations, the intricate pathomechanisms underlying cataract formation in individuals affected by RP remain elusive. Therefore, our study aims to elucidate the potential pathogenesis of cataracts in an RP model using splicing factor subunit 3b (sf3b4) mutant zebrafish. By analyzing our previously published transcriptome dataset, we identified that, in addition to RP, cataract was listed as the second condition in our transcriptomic analysis. Furthermore, we confirmed the presence of nucleus retention in the lens fiber cells, along with abnormal cytoskeleton expression in both the lens fiber cells and lens epithelial cells in sf3b4-depleted fish. Upon closer examination, we identified 20 differentially expressed genes (DEGs) that played a role in cataract formation, with 95 % of them related to the downregulation of structural lens proteins. Additionally, we also identified that among all the DEGs, 13 % were associated with fibrotic processes. It seems that the significant upregulation of inflammatory mediators, in conjunction with TGF-β signaling, plays a central role in the cellular biology of PSC and posterior capsular opacification (PCO) in sf3b4 mutant fish. In summary, our study provides valuable insights into cataract formation in the RP model of sf3b4 mutants, highlighting its complexity driven by changes in structural lens proteins and increased cytokines/growth factors.

Congenital cataracts affect the retinal visual cycle and mitochondrial function: A multi-omics study of GJA8 knockout rabbits

Congenital cataracts are a threat to visual development in children, and the visual impairment persists after surgical treatment; however, the mechanisms involved remain unclear. Previous clinical studies have identified the effect of congenital cataracts on retinal morphology and function. To further understand the molecular mechanisms by which congenital cataracts affect retinal development, we analyzed retina samples from 7-week-old GJA8-knockout rabbits with congenital cataracts and controls by four-dimensional label-free quantification proteomics and untargeted metabolomics. Bioinformatics analysis of proteomic data showed that retinol metabolism, oxidative phosphorylation, and fatty acid degradation pathways were downregulated in the retinas of rabbits with congenital cataracts, indicating that their visual cycle and mitochondrial function were affected. Additional validation of differentially abundant proteins related to the visual cycle and mitochondrial function was performed using Parallel reaction monitoring and western blot experiments. Untargeted metabolome analysis showed significant upregulation of the antioxidant glutathione and ascorbic acid in the retinas of rabbits with congenital cataracts, indicating that their oxidative stress balance was not dysregulated. SIGNIFICANCE: Congenital cataracts in children can alter retinal structure and function, yet the mechanisms are uncertain. Here is the first study to use proteomics and metabolomics approaches to investigate the effects of congenital cataracts on retinal development in the early postnatal period. Our findings suggest that congenital cataracts have an impact on the retinal visual cycle and mitochondrial function. These findings give insight on the molecular pathways behind congenital cataract-induced visual function impairment in the early postnatal period.

Novel and recurrent FBN1 mutations causing Marfan syndrome in two Chinese families

Background

To explore the genetic defects of two families with autosomal dominant Marfan syndrome (MFS).

Methods

Two families with MFS were enrolled in this study. The detailed ocular presentations of the patients were recorded. Whole exome sequencing was performed to explore the pathogenic variants and Sanger sequencing was performed to confirm the gene mutations. Segregation analysis among the family members was made and bioinformatics analysis was performed to predict the functional impact of the mutations.

Results

The main ocular presentations of the probands were increased axial length and ectopia lentis. Using whole exome sequencing and Sanger sequencing, a novel heterozygous missense mutation (c.5060G > C, p.Cys1687Ser) and a recurrent missense mutation (c.2168A > T, p.Asp723Val) were identified within FBN1, which were co-segregated with the MFS phenotype in the families. Evolutionary conservation analysis showed that codons 723 and 1,687 were highly conserved among several species. Functional impact predictions made using several online programs suggested that the mutations were pathogenic.

Conclusion

We identified a novel and a recurrent missense mutation in FBN1 in two Chinese families with MFS using whole exome sequencing, and our bioinformatics analysis indicated that the mutations were disease-causing. Our results expand the mutation spectrum of FBN1 and could help us better understand the genetic defects of the patients with MFS.

Novel clinical presentation and PAX6 mutation in families with congenital aniridia

Purpose

To explore the clinical phenotype and genetic defects of families with congenital aniridia.

Methods

Four Chinese families with aniridia were enrolled in this study. The detailed ocular presentations of the patients were recorded. Whole exome sequencing (BGI MGIEasy V4 chip) was used to detect the gene mutation. Sanger sequencing was performed to validate the potential pathogenic variants, and segregation analysis was performed on all available family members.

Results

By whole exome sequencing and Sanger sequencing, three recurrent mutations (c.112del, p.Arg38Glyfs*16; c.299G > A, p.Trp100* and c.718C > T, p.Arg240*) and one novel mutation (c.278_281del, p.Glu93Alafs*30) of PAX6 were identified. All the mutations were co-segregated with the phenotype in the families. We also observed spontaneous anterior lens capsule rupture in aniridia for the first time.

Conclusion

We report spontaneous anterior lens capsule rupture as a novel phenotype of aniridia and three recurrent mutations and one novel mutation of PAX6 in families with aniridia. Our results expanded the phenotype and genotype spectra of aniridia and can help us better understand the disease.