University of Michigan scientists discovers that it only 2 percent of the human genome code for cellular functions of proteins while 98 percent of the noncoding DNA accounts for gene expression.
This function is significant as the same DNA comprises all kinds of cell.
This implies that a hair cell is different from a brain cell because of the activated genes.
This team of researchers investigates the noncoding DNA's variation in genes through complex computation methods and how this variation affects the susceptibility of humans to diseases.
The journal Genetics have published their study regarding the comparison of five kinds of regulatory regions and how these regions behave in various kinds of cells.
"When people try to look at how gene regulation occurs, they look at different epigenomic information using sequencing, trying to understand molecular profiles," says lead author Arushi Varshney, a Ph.D. candidate in human genetics.
Epigenomics is the changes brought about by how genes are organized due to other factors excluding the sequence of DNA.
Recent discoveries have shown that the slight changes in DNA or genetic variants that are connected with diseases are prone in areas of the genome that function as gene regulatory elements named as enhancers and promoters.
Enhancers increase the gene's transcription and promoters start gene transcription.
"There were a number of papers coming out describing different classes of gene regulatory elements, and it was not clear how they are related," explains Stephen Parker, Ph.D., assistant professor of computational medicine and bioinformatics and of human genetics.
"Our paper was the first to really compare them," Parker says. "One of the things that came out is that they're all different and act differently in different cell types."
The team of scientists also discovered that variation in genes in the enhancers also do not significantly affect their target genes. This can cause a problem for the researchers who are comparing a large number of people's genomes to find the specific variation in genes related to traits in disease.
"What it means is we're going to need really large sample sizes to see effects," Parker says.
One of their added discoveries may be able to provide an explanation of how variation in genes in regulatory elements increase the chances of having a specific kind of disease.
The team also recommends that enhancers and promoters that are cell-specific make transcription easier to happen under specific environmental conditions.
It is made possible by making the chromatin gain higher accessibility.
The next phase of the research involves looking at the cell's specific gene expression. Varshney emphasizes, "For example, if you're trying to look at type 2 diabetes, maybe look at cells under high glucose conditions, then look at the gene expression and how genetic variants affect gene expression."
"Then, maybe you would be better able to explain how this genetic variant predisposes you to get a disease."
