Washington: More than a
million single-letter variations in human DNA reveal that most
genetic mutations originated, in evolutionary terms, fairly
recently, a new study found.
These kinds of mutations change one nucleotide - an A, C, T or G -
in the DNA sequence. Over 86 percent of the harmful protein-coding
mutations of this type arose in humans just during the past 5,000
to 10,000 years.
Nucleotides are biological molecules that form the building blocks
of nucleic acids (DNA and RNA) and serve to carry packets of
energy within the cell (ATP), the journal Nature reports.
Some of the remaining mutations of this nature may have no effect
on people, and a few might be beneficial, according to project
While each specific mutation is rare, the findings suggest that
the human population acquired an abundance of these
single-nucleotide genetic variants in a relatively short time.
"The spectrum of human diversity that exists today is vastly
different than what it was only 200 to 400 generations ago," said
Joshua Akey, associate professor of genome sciences at the
University of Washington, Seattle, who co-authored the study with
colleague Wenqing Fu, according to a Washington statement.
He is one of several leaders of a multi-institutional effort among
evolutionary geneticists to date the first appearance of a
multitude of single nucleotide variants in the human population.
The work stems from collaboration among many genome scientists,
medical geneticists, molecular biologists and biostatisticians at
the UW, the University of Michigan, Baylor College of Medicine in
Houston, the Broad Institute at MIT and Harvard, and the
Population Genetics Working Group.
The study is part of the Exome Sequencing Project of the National
Heart, Lung, and Blood Institute at the National Institutes of