Genetic variation recent, varies among populations
Nearly three-quarters of mutations in genes that code for proteins – the workhorses of the cell – occurred within the past 5,000 to 10,000 years, fairly recently in evolutionary terms, said a national consortium of genomic and genetic experts, including those at Baylor College of Medicine.
"One of the most interesting points is that Europeans have more new deleterious (potentially disease-causing) mutations than Africans," said Dr. Suzanne Leal, professor of molecular and human genetics at BCM and an author of the report. She is also director of the BCM Center for Statistical Genetics. "Having so many of these new variants can be partially explained by the population explosion in the European population. However, variation that occur in genes that are involved in Mendelian traits and in those that affect genes essential to the proper functioning of the cell tend to be much older." (A Mendelian trait is controlled by a single gene. Mutations in that gene can have devastating effects.)
How events affected genome
The amount variation or mutation identified in protein-coding genes (the exome) in this study is very different from what would have been seen 5,000 years ago, said Leal and her colleagues in the report that appears online in the journal Nature. The report shows that "recent" events have a potent effect on the human genome.
Eighty-six percent of the genetic variation or mutations that are expected to be harmful arose in European-Americans in the last five thousand years, said the researchers.
The researchers used established bioinformatics techniques to calculate the age of more than a million changes in single base pairs (the A-T, C-G of the genetic code) that are part of the exome or protein-coding portion of the genomes (human genetic blueprint) of 6,515 people of both European-American and African-American decent. The research was an offshoot of the National Heart, Lung and Blood Institute Exome Sequencing Project.
Human population increase
"The recent dramatic increase in human population size, resulting in a deluge of rare functionally important variation, has important implications for understanding and predicting current and future patterns of human disease and evolution," wrote the authors in their report.
Others institutions that took part in this research include the University of Washington, Seattle; University of Michigan, Ann Arbor; the Broad Institute of MIT and Harvard. Other BCM researchers who took part include Dr. Christie M. Ballantyne, Mengyuan Kan, Fremiet Lara-Garduno, Dajiang J. Liu, Gao Wang and Dr. Haleh Sangi-Haghpeykar.
Funding for the research came from the GO (Grand Opportunity) Exome Sequencing Project (NHLBI grants RC2 HL-103010 (Heart GO), RC2 HL-102923 (Lung GO) and RC2 HL-102924 (WHISP). The exome sequencing was supported by NHLBI grants RC2HL-102925 (Broad GO) and RC2 HL-102926 (Seattle GO).