|Hot spots in human DNA shed light on humans' complex evolutionary history/ Photo By dolgachov via 123RF|
Research has shown that there is a very complex story behind how humans are very adaptable and yet delicate at the same time. A new research is looking into the hot spots of genetic variation in the human genome and examining the sections of the human DNA that are most likely to be different from one person to another.
What is that thing that makes a person different from the next? How do these differences change through time?
Biologists from the University of Buffalo are looking at one aspect of this question wherein they are examining the hot spots of genetic variation in the human genome. The findings resulted in a complex evolutionary history that showed the delicate nature of human DNA. At the same time, it shows the adaptability of the species.
According to Omer Gokcumen, PhD, assistant professor of biological sciences in the University of Buffalo College of Arts and Sciences, they have made progress in understanding how the variations in the human genome occur. The research aims to study which parts of the genome are protected and preserved through evolution and which parts are not protected and why.
There have also been previous works that showed the structural variations according to Gokcumen, such as deletions, alterations, and duplications of DNA. They are not distributed throughout the genome. The genome has deserts and hot spots. Whether there is a meaning to this or it is just a random thing brought about by evolution is what the research wants to find out.
The Human Genome
The human genome is everything about a person's DNA–the genes that influence the eye color, risk of disease, and temperament. The rest is made up of noncoding DNA whose function or lack of is still to be debated.
The genome of every person is different. The new research looks into the DNA of more than 2,500 persons. Scientists are paying more attention to the parts of the genome that differ most among people. There are 1,148 areas that have high structural variants that include DNA that has been duplicated, inserted, deleted, or repeated.
Human DNA's malleability
Based on the examination of the "hot spots" as the study termed it, it reveals a complex story about humans' evolution. The hot spots are found in gene-poor regions of the genome. According to Gokcumen, the altering genes can have a profound effect on health problems so it makes sense that the gene-rich areas will be more conserved through evolution.
There is still a small subset of structural variant hot spots found in the part of the genome that contains important genes. Here, the genes for the sense of smell, skin, and blood, and immunity to diseases are overrepresented based on the findings of the study.
There is a possible explanation as to why the gene-heavy hot spots exist - one could be balancing selection wherein forces drive a species to preserve a particular set of traits.
In the study, thalassemia, a rare blood disorder was found in 16 percent of genes in populations in sub-Saharan Africa. While evolution has tried to remove this disorder from human societies, in other parts of the world, this disorder remains because it is useful in that area. Gokcumen said that the deletion might confer resistance to malaria which is a major disease in the area.
He added that "There's an evolutionary reason why this mutation is lingering, despite its ill effects. It's actually beneficial too, at least for some populations. Balancing selection is important for adaptation, and we think it contributes to the development of some structural variant hot spots."
The balancing selection shows that humans are adaptable. However, another result from the study also means that humans are also delicate and problems can easily arise. This has something to do with the malleability of human DNA and that there are some hot spots of variation that can be found in the genome that can be easily altered.
|The malleability of human DNA and hot spots in the genome are more prone to being altered/ Photo By Sergey Nivens via 123RF|
Genetic mutations in the region are not devastating but when there are large deletions, it can begin in one hotspot and may lead to the erasure of the entire genes in between which can cause many health complications.
Another example in the study is the number of consecutive structural variant hot spots. They lie on either side of the short stature homeobox (SHOX) gene. Deletion of this gene can lead to bone growth disorder that causes very short stature. Some people who are missing the SHOX gene, where there are deletions of a gene in one hot spot, spanned the entire gene and ended in a second hot spot.
Gokcumen and Lin ran statistical tests and found out that the start and end points of large genetic mutations were in structural variant hot spots more often than they expected them to be.