Small damages to sequences in the human genome are causing evolutionary changes in our DNA, according to a group of Japanese geneticists.
Their recent findings prove that a common form of DNA damage caused by oxidation (called 8-oxoG) is a primary cause of mutagenesis, damage to DNA during the genome replication process that causes mutations in the resulting DNA molecules.
Succinctly, the human race is genetically mutating, and we now may know how and why--at least in part.
Japanese geneticist Yusaku Nakabeppu of Kyushu University and his team released their findings Monday in Genome Research.
"Our findings suggest that 8-oxoG is one of the main causes of frequent recombinations and SNPs (single nucleotide polymorphisms) in the human genome, which largely contribute to the genomic diversity in human beings," the researchers concluded in their Genome Research journal article.
DNA is made up of four nucleobases: adenine, cytosine, guanine and thymine. Combinations of these four bases make up the human genome. Among the four bases, guanine is the nucleotide most susceptible to oxidation, and the most common oxidation product of guanine is known as 8-oxoG (8-oxoguanine). It is this prevalent substance that is thought to cause SNPs.
SNPs are subtle changes in chemical pairings found in the DNA sequence. SNPs and frequent recombination of code result in genetic mutation.
These changes in chemical pairings sometimes cluster in one area of the DNA sequence but, until recently, scientists were unsure of why. Nakabeppu and his team have found a causal link between 8-oxoG and clusters of sequence variations in the human genome.
While the specific environmental factors causing the mutation were not part of the research, the study established that the change is not happening in a closed system. The scientists agree with previous studies that have seen exposure to ionizing radiation and other environmental causes as genetic threats, according to their article.
Previously, SNPs were thought to be natural occurrences caused by internal byproduct releases from chemical reactions.
The Japanese researchers used genetic material from two healthy men and two healthy women (all unrelated genetically) in the study.
Scientific American originally disclosed Genome Research's release of the findings.