Genes that could be involved in heart development have been identified using a method that looks for candidate genes not solely expressed in heart tissue.
While heart disease is a common cause of death in newborns, the genetic causes of 80 percent of congenital heart diseases are not understood, making it difficult to design prenatal genetic tests for screening. To tackle this lack of knowledge, a team from Monash University, Melbourne, Australia decided to cast the net wider when looking for candidate genes to research.
'[Previous methods] focused on screening genes that are present in the heart only – an approach that often overlooks genes that are present in other tissues as well, despite still playing important roles in heart development,' said Dr Hieu Nim from Australian Regenerative Medicine Institute at Monash University, the first author of the study, published in Genome Biology.
It is understood that transcription factors that regulate the genes involved in heart development regulate them via parts of the genome known as cis-regulatory elements. Researchers hypothesised that if they could identify regulatory elements common to genes involved in heart development, they could identify genes not uniquely expressed in the heart tissue as candidates for further research into congenital heart disease.
By carrying out a genome-wide screen of embryonic mouse hearts, limbs, liver and brain the researchers identified 1311 genes with both cardiac-specific promoters and enhancers involved in genetic regulation of heart development.
Of these genes, 163 were found to have a high level of expression in the heart and 78.5 percent had a known role in heart tissue. This left 35 genes with no known role in heart development.
To test the impact of loss of these genes, researchers performed knockouts of equivalents genes in the heart tissue of fruit flies. Of the 24 genes tested inactivation of 17 of them reduced the viability of adults. This suggests they could play an important role in development or function of the heart.
The experiments outlined in the paper revealed 'a long list of high-quality candidate genes for causing heart abnormalities in humans, giving real insight into just how susceptible this organ is to genetic mutations,' Dr Travis Johnson, who was also involved in the study, said.
'We now need to conduct functional studies on all of these genes in animal experiments to determine what they actually do, so its early days (…) But we now have an excellent starting point.'
Researchers argue this method could be used to identify genes responsible for development and function of other organs and tissues that may previously have been overlooked as they were expressed in multiple tissues.