Researchers have looked deeper into the makeup of DNA to get clues about why people might have different colors of hair or eyes, why some are taller or heavier and why some are more susceptible to certain diseases.
They found that changes in chromatin structure and transcription factor binding could influence such traits. The research was reported in the journal Science Express this week.
The findings bring science and medicine a step closer to personalized medicine based on a close reading of an individual's genome.
The project was conducted by Dr. Vishy Iyer, an associate professor in the Section of Molecular Genetics and Microbiology at The University of Texas at Austin; Dr. Greg Crawford, an assistant professor in the Department of Pediatrics, Division of Medical Genetics at Duke University; Dr. Ewan Birney, senior scientist at the European Molecular Biology Laboratory working at the European Bioinformatics Institute; and colleagues.
The study looked at the structure of chromatin, which is how DNA is packaged in cells, and the binding of protein transcription factors, which regulate gene expression, and what impact those mechanisms of gene regulation have on gene expression.
The researchers found that chromatin structure is different in a significant way between people and that the difference can be inherited.
"We know that DNA sequence can be inherited but now we're showing that these things that go on top of it like the way genes are regulated, can also be inherited, and that helps explain why you might see differences between people in terms of their physical characteristics like color and disease susceptibility," Iyer said.
One of the challenges in applying genetic information in treating disease has been that it's hard to isolate the genes causing a particular disease. More than one gene and even networks of genes have been implicated in some diseases. Even parts of the genome that seem to have no function, called non-coding, appear to affect disease.
The study's findings mean researchers can home in on those non-coding areas by looking at how chromatin structure and transcription factor binding vary between someone with a disease and someone who does not have that disease.
"There are hundreds of diseases in which DNA changes are associated with the diseases but we have no idea of what the mechanism is, how these changes cause the disease or even which changes are really causative, as opposed to just coming along for the ride," Iyer said.
"Our approach allows us to potentially test some of these changes because we can look at the entire genome and say, 'Can you have some change in the DNA that's not merely associated with Type II diabetes, but also has a functional effect on chromatin or the binding of regulators?'"
He said the study shows that such changes in chromatin structure and the binding of regulators do exist and they can be inherited.
The laboratories examined cells from two sets of parents and a child from each set of parents. One family was from Utah and of European ancestry and the other was Yoruban (a West African ethnic group) from Ibadan, Nigeria.