Deciphering novel TCF4-driven mechanisms underlying a common triplet repeat expansion-mediated disease

Fuchs endothelial corneal dystrophy (FECD) is an age-related cause of vision loss, and the most common repeat expansion-mediated disease in humans characterised to date. Up to 80% of European FECD cases have been attributed to expansion of a non-coding CTG repeat element (termed CTG18.1) located within the ubiquitously expressed transcription factor encoding gene, TCF4. The non-coding nature of the repeat and the transcriptomic complexity of TCF4 have made it extremely challenging to experimentally decipher the molecular mechanisms underlying this disease. Here we comprehensively describe CTG18.1 expansion-driven molecular components of disease within primary patient-derived corneal endothelial cells (CECs), generated from a large cohort of individuals with CTG18.1-expanded (Exp+) and CTG 18.1-independent (Exp-) FECD. We employ long-read, short-read, and spatial transcriptomic techniques to interrogate expansion-specific transcriptomic biomarkers. Interrogation of long-read sequencing and alternative splicing analysis of short-read transcriptomic data together reveals the global extent of altered splicing occurring within Exp+ FECD, and unique transcripts associated with CTG18.1-expansions. Similarly, differential gene expression analysis highlights the total transcriptomic consequences of Exp+ FECD within CECs. Furthermore, differential exon usage, pathway enrichment and spatial transcriptomics reveal TCF4 isoform ratio skewing solely in Exp+ FECD with potential downstream functional consequences. Lastly, exome data from 134 Exp- FECD cases identified rare (minor allele frequency 15) TCF4 variants in 7/134 FECD Exp- cases, suggesting that TCF4 variants independent of CTG18.1 may increase FECD risk. In summary, our study supports the hypothesis that at least two distinct pathogenic mechanisms, RNA toxicity and TCF4 isoform-specific dysregulation, both underpin the pathophysiology of FECD. We anticipate these data will inform and guide the development of translational interventions for this common triplet-repeat mediated disease

High-throughput functional analysis of autism genes in zebrafish identifies convergence in dopaminergic and neuroimmune pathways

Advancing from gene discovery in autism spectrum disorders (ASDs) to the identification of biologically relevant mechanisms remains a central challenge. Here, we perform parallel in vivo functional analysis of 10 ASD genes at the behavioral, structural, and circuit levels in zebrafish mutants, revealing both unique and overlapping effects of gene loss of function. Whole-brain mapping identifies the forebrain and cerebellum as the most significant contributors to brain size differences, while regions involved in sensory-motor control, particularly dopaminergic regions, are associated with altered baseline brain activity. Finally, we show a global increase in microglia resulting from ASD gene loss of function in select mutants, implicating neuroimmune dysfunction as a key pathway relevant to ASD biology

Exploring Parental Attitudes on Autism Genetic Testing After Receiving Non-Pathogenic Results

Whole exome sequencing (WES) is quickly moving toward becoming a first-tier test for autism spectrum disorder (ASD); however, the diagnostic yield of these tests can be quite low. Many parents will not receive a molecular diagnosis to explain the underlying cause of their child’s autism, so it is important to understand how these parents view genetic testing: both regarding satisfaction with genetic testing and if such results cause significant emotional distress. We surveyed 520 parents who enrolled their child with ASD in SPARK Research Match and received a null genetic finding through WES. We found that, despite not receiving a pathogenic genetic result for ASD, parents were satisfied with genetic testing, and they experienced low levels of emotional distress upon receiving results. Additionally, parents with lower understanding of the test results had significantly decreased satisfaction with testing and experienced increased emotional distress. Keywords: autism spectrum disorder, genetic testing, exome sequencing, parents, perceptions, attitudes, utility, value, motivations, knowledge What is known about this topic: Prior studies exploring parental attitudes towards genetic testing for ASD are generally positive, however few studies have examined how parents feel about genetic testing for autism after they have undergone the process. Even though the diagnostic yield of ASD testing can be quite low, no studies have explored parental satisfaction of going through ASD testing and not receiving a pathogenic result for their child. What this paper adds to the topic: Our study demonstrates that parents are very satisfied with genetic testing even if their child does not receive a pathogenic result, and when they receive such results, they do not experience significant distressing emotions. Additionally, we find that parents who feel like they do not understand the test results have lower satisfaction as well as more emotional distress upon finding that their child does not have a positive genetic test result for ASD