A rare case of 3C disease: Ritscher-Schinzel syndrome presenting with recurrent talipes equinovarus

Understanding the Genetic and Non-Genetic Interconnections in the Aetiology of Syndromic Congenital Heart Disease: An Updated Review: Part 2

PURPOSE OF REVIEW

Approximately 30% of syndromic cases diagnosed with CHD, which lure us to further investigate the molecular and clinical challenges behind syndromic CHD (sCHD). The aetiology of sCHD in a majority of cases remains enigmatic due to involvement of multiple factors, namely genetic, epigenetic and environmental modifiable risk factors for the development of the disease. Here, we aim to update the role of genetic contributors including chromosomal abnormalities, copy number variations (CNVs) and single gene mutations in cardiac specific genes, maternal lifestyle conditions, environmental exposures and epigenetic modifiers in causing CHD in different genetic syndromes.

RECENT FINDINGS

The exact aetiology of sCHD is still unknown. With the advancement of next-generation technologies including WGS, WES, transcriptome, proteome and methylome study, numerous novel genes and pathways have been identified. Moreover, our recent knowledge regarding epigenetic and environmental regulation during cardiogenesis is still evolving and may solve some of the mystery behind complex sCHD. Here, we focus to understand how the complex combination of genetic, environmental and epigenetic factors interact to interfere with developmental pathways, culminating into cardiac and extracardiac defects in sCHD.

Whole genome sequencing identifies ANXA3 and MTHFR mutations in a large family with an unknown equinus deformity associated genetic disorder

The aim of this study was to characterize a previously uncharacterized genetic disorder associated with equinus deformity in a large Chinese family at the genetic level. Blood samples were obtained and whole genome sequencing was performed. Differential gene variants were identified and potential impacts on protein structure were predicted. Based on the control sample, several diseases associated variants were identified and selected for further validation. One of the potential variants identified was a ANXA3 gene [chr4, c.C820T(p.R274*)] variant. Further bioinformatic analysis showed that the observed mutation could lead to a three-dimensional conformational change. Moreover, a MTHFR variant that is different from variants associated with clubfoot was also identified. Bioinformatic analysis showed that this mutation could alter the protein binding region. These findings imply that this uncharacterized genetic disorder is not clubfoot, despite sharing some similar symptoms. Furthermore, specific CNV profiles were identified in association with the diseased samples, thus further speaking to the complexity of this multigenerational disorder. This study examined a previously uncharacterized genetic disorder appearing similar to clubfoot and yet having distinct features. Following whole genome sequencing and comparative analysis, several differential gene variants were identified to enable a further distinction from clubfoot. It is hoped that these findings will provide further insight into this disorder and other similar disorders.