First Mexican-American and African-American genomes completed

Studies hint that genetic diversity among Native Americans may rival that seen in some African populations

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.

Tina Hesman Saey is the senior staff writer and reports on molecular biology. She has a Ph.D. in molecular genetics from Washington University in St. Louis and a master’s degree in science journalism from Boston University.

More Stories from Science News on Humans