Project description:To identify the molecular causes of heterotaxy syndrome patients with congenital heart defects, an Affymetrix CytoScan HD array was used to identify possible pathogenic CNVs in 63 patients. A total of 59 samples passed initial quality control.
Project description:Heterotaxy is a disorder characterized by severe congenital heart defects (CHDs) and abnormal left-right patterning in other thoracic or abdominal organs. Clinical and research-based genetic testing has previously focused on evaluation of coding variants to identify causes of CHDs, leaving non-coding causes of CHDs largely unknown. Variants in the transcription factor Zinc finger of the cerebellum 3 (ZIC3) cause X-linked heterotaxy. We identified an X-linked heterotaxy pedigree without a coding variant in ZIC3. Whole genome sequencing revealed a deep intronic variant (ZIC3 c.1224+3286A>G) predicted to alter RNA splicing. An in vitro minigene splicing assay confirmed the variant acts as a cryptic splice acceptor. CRISPR/Cas9 served to introduce the ZIC3 c.1224+3286A>G variant into human embryonic stem cells demonstrating pseudoexon inclusion caused by the variant. Surprisingly, Sanger sequencing of the resulting ZIC3 c.1224+3286A>G amplicons revealed several isoforms, many of which by-pass the normal coding sequence of the third exon of ZIC3, causing a disruption of a DNA binding domain and a nuclear localization signal. Short- and long-read mRNA sequencing confirmed these initial results and identified additional splicing patterns. Assessment of four isoforms determined abnormal functions in vitro and in vivo while treatment with a splice-blocking morpholino partially rescued ZIC3. These results demonstrate that pseudoexon inclusion in ZIC3 can cause heterotaxy and provide functional validation of non-coding disease causation. Our results suggest the importance of non-coding variants in heterotaxy and the need for improved methods to identify and classify non-coding variation that may contribute to CHDs.
Project description:<p>Heterotaxy syndrome is a congenital anomaly syndrome accompanied by thoracic and abdominal situs abnormalities. The study cohort comprises of individuals with heterotaxy or related congenital heart disease (CHD) who have undergone exome sequencing. The purpose of the study is to elucidate the molecular genetics of the disorder as well as contribute to knowledge about the biology of normal and abnormal development of left-right anatomic asymmetry. These results will further help delineate genotype-phenotype associations and provide important information on the causes, management, and prognosis of heterotaxy syndrome.</p>
Project description:Exome sequencing of families with Congenital Heart Defects of diverse sub-phenotypes. Comprises both parent-offspring trios for sporadic cases and multiplex families. Collaboration with David Brook, University of Nottingham. Funded by the British Heart Foundation.
Project description:Molecular Signatures of cardiac defects in Down syndrome lymphoblastoid cell lines. In this study, we want to identify genes and pathways specifically dysregulated in atrioventricular septal defect and /or atrial septal defect + ventricular septal defect in case of trisomy 21. Total RNA obtained from DS lymphoblastoid cell lines without congenital heart disease compared to cell lines from DS with congenital heart disease.