Biology subjects

Zackai, E.

Publications and source records attributed to Zackai, E..

3 recordsLinked to original sources

bioRxiv2022

Chromatin regulators in the TBX1 network confer risk for conotruncal heart defects in 22q11.2DS and sporadic congenital heart disease

BackgroundCongenital heart disease (CHD) affecting the conotruncal region of the heart, occur in half of patients with 22q11.2 deletion syndrome. This syndrome is a rare disorder with relative genetic homogeneity that can facilitate identification of genetic modifiers. Haploinsufficiency of TBX1, mapped to the 22q11.2 region, encoding a T-box transcription factor, is one of the main genes for the etiology of the syndrome. We suggest that genetic modifiers of CHD in patients with 22q11.2 deletion syndrome may be in the TBX1 gene network. MethodsTo identify genetic modifiers of 22q11.2 deletion syndrome, we analyzed whole genome sequence of subjects with 22q11.2DS, of which 456 were cases with conotruncal heart defects and 537 were controls with normal cardiac structures. We retained the most damaging rare coding variants and examined 19 functional gene sets for association that were weighted upon expression of genes in cardiac progenitor cells in mouse embryos identified by RNA-sequencing. ResultsWe identified rare damaging coding variants in chromatin regulatory genes as modifiers of conotruncal heart defects in 22q11.2DS. Chromatin genes with recurrent damaging variants include EP400, KAT6A, KMT2C, KMT2D, NSD1, CHD7 and PHF21A. In total, we identified 37 chromatin regulatory genes, that may increase risk for conotruncal heart defects in 8.5% of 22q11.2 deletion syndrome cases. Many of these genes were identified as risk factors for sporadic CHD in the general population increasing the likelihood that these genes are medically important contributors for CHD. These genes are co-expressed in cardiac progenitor cells with TBX1, suggesting that they may be in the same genetic network. Some of the genes identified, such as KAT6A, KMT2C, CHD7 and EZH2, have been previously shown to genetically interact with TBX1 in mouse models, providing mechanistic validation of these genes found. ConclusionsOur findings indicate that disturbance of chromatin regulatory genes impact a TBX1 gene network serving as genetic modifiers of 22q11.2 deletion syndrome. Since some of these chromatin regulatory genes were found in individuals with sporadic CHD, we suggest that there are shared mechanisms involving the TBX1 gene network in the etiology of CHD.

genetics↗

bioRxiv2020

CBX1 mutations cause a neurodevelopmental syndrome due to heterochromatin organizational alterations

PurposeThis study aimed to establish variants in CBX1, encoding heterochromatin protein 1{beta} (HP1{beta}), as a cause of a novel syndromic neurodevelopmental disorder. MethodsPatients with CBX1 variants were identified, and clinician researchers were connected using GeneMatcher and physician referrals. Clinical histories were collected from each patient. To investigate the pathogenicity of identified variants, we performed in vitro cellular assays, neurobehavioral and cytological analyses of neuronal cells obtained from newly generated Cbx1 mutant mouse lines. ResultsIn three unrelated individuals with developmental delay, hypotonia, and autistic features, we identified heterozygous de novo variants in CBX1. The identified variants were in the chromodomain, the functional domain of HP1 {beta}, which mediates interactions with chromatin. Cbx1 chromodomain mutant mice displayed increased latency-to-peak response, suggesting the possibility of synaptic delay or myelination deficits. Cytological and chromatin immunoprecipitation experiments confirmed the reduction of mutant HP1{beta} binding to heterochromatin, while HP1{beta} interactome analysis demonstrated that the majority of HP1{beta}-interacting proteins remained unchanged between the wild-type and mutant HP1{beta}. ConclusionThese collective findings confirm the role of CBX1 in developmental disabilities through the disruption of HP1{beta} chromatin binding during neurocognitive development. As HP1{beta} forms homodimers and heterodimers, mutant HP1{beta} likely sequesters wild-type HP1{beta} and other HP1 proteins, exerting dominant-negative effects.

genetics↗

bioRxiv2019

Novel truncating mutations in CTNND1 cause a dominant craniofacial and cardiac syndrome

AbstractCTNND1 encodes the p120-catenin (p120) protein, which has a wide range of functions, including the maintenance of cell-cell junctions, regulation of the epithelial-mesenchymal transition and transcriptional signaling. Due to advances in next generation sequencing, CTNND1 has been implicated in human diseases including cleft palate and blepharocheilodontic syndrome (BCD) albeit only recently. In this study, we identify eight novel protein-truncating variants, six de novo, in thirteen participants presenting with craniofacial dysmorphisms including cleft palate and hypodontia, as well as congenital cardiac anomalies, limb dysmorphologies and neurodevelopmental disorders. Using conditional deletions in mice as well as CRISPR/Cas9 approaches to target CTNND1 in Xenopus, we identified a subset of phenotypes that can be linked to p120-catenin in epithelial integrity and turnover, and additional phenotypes that suggest mesenchymal roles of CTNND1. We propose that CTNND1 variants have a wider developmental role than previously described, and that variations in this gene underlie not only cleft palate and BCD but may be expanded to a broader velocardiofacial-like syndrome.

genetics↗