Researchers are looking into the hearts of fruit flies and mice in order to detect two of the most important genes that are directly related to congenital heart defects usually found in people diagnosed with Down Syndrome.

Ethan Bier and his team from UC San Diego, Sanford-Burnham Medical Research and University of Utah focused on two specific genes that are activated for the disruption of cardiac development and function.

The congenital heart disease that is associated with Down Syndrome puts individuals with the condition at high risk. It is also the major cause of cognitive impairment when individuals have an extra chromosome 21.

"Chromosome 21 is considered as the shortest human chromosome and it is highly important in genetic mapping studies for individuals who have been diagnosed with Down syndrome," says Bier, the primary author of the research.

"Our research team has identified a small region of chromosome 21 that is involved in causing congenital heart defects."

Due to the difficulty involved in trying to identify the exact genes that are related to congenital heart defects, Bier and his team studied fruit flies and mice, two of the animals that closely resemble the genes of humans.

The fruit flies were evaluated for multiple genetic interactions involving pumping the blood from the heart and vice versa. The researchers then found out that the pair of genes that they were looking for was DSCAM and COL6A2. These genes, when put together, can cause severe defects when there is a surplus in their production.

Then the researchers turned their attention to mice by increasing the amount of these two genes in the hearts of the mice. Initial observations showed that the mice had elevated activity for each of the genes. The mice were then cross-bred to create an offspring that also has an elevated amount of these two genes. Both the parent mice and their offspring had indications of cardiac defects when evaluated thereafter.

"The overproduction of the two genes significantly reduced heart function and led to fatal cardiac arrests," concluded Bier.

The study was published in PLoS Genetics on November 3.