BOSTON — One Mexican-American person’s genome shows just how little is
known about human genetic diversity in the Americas.
Researchers recently compiled the complete genetic instruction books for
two people of mixed ethnic ancestry — a Mexican-American and an
African-American. Carlos Bustamante of Stanford University School of Medicine
reported the accomplishment June 12 at Genetics 2010: Model Organisms to Human Biology, a meeting of the Genetics Society of America.
Not surprisingly, analyses of the two people’s DNA revealed genomes that
reflect the people’s mixed ancestry. The African-American person has genetic
roots in both West Africa and Europe, while the Mexican-American carries the
genetic legacies of both Native American and European ancestors.
More unexpectedly, fine-scale DNA analysis shows that Native Americans may
have as much genetic diversity as some African populations known to have a
great deal of genetic diversity.
Researchers surveyed the genomes for single DNA “letter” variations
called single nucleotide polymorphisms, or SNPs, which can serve as markers of diversity. About 12 percent of the SNPs found in parts of the genome the
Mexican-American person inherited from Native American ancestors have not been found in any other person, Bustamante reported. That is about the same
percentage of new SNPs that researchers found when they cataloged Archbishop
Desmond Tutu’s genetic blueprint (SN:
3/13/10, p. 16) earlier this year.
Based on such findings, the 1000 Genomes Project — an effort to compile
a complete catalog of human genetic diversity — has already been expanded to
include more Native Americans, Bustamante says.
