An international research team has performed a genetic study which reveals that genomic diversity among African and African-American populations are far more complex than originally thought.
The research team, led by scientists from the University of Pennsylvania and Cornell University, has collected and analyzed genotype data from 365 African-Americans, 203 people from 12 West African populations and 400 Europeans from 42 countries to provide a genome-wide perspective of African and African-American ancestry.
The data has revealed that genomic diversity among African and African-American populations are far more complex than originally thought and reflect deep historical, cultural and linguistic impacts on gene flow among populations.
The data also points to the ability of geneticists to reliably discern ancestry using such data.
Scientists found, for example, that they could distinguish African and European ancestry at each region of the genome of self-identified-African Americans.
Sarah Tishkoff, a geneticist at Penn, and Carlos Bustamante, a computational biologist at Cornell, led the study to analyze 300,000 genetic markers from across the genome from West African, African-American and European-American populations to see whether they could reliably distinguish ancestry.
The team found that, while some West African populations are nearly indistinguishable, there are clear and discernible genetic differences among some groups, divided along linguistic and geographic lines.
This newly acquired genetic data revealed a number of important advances, like, among the 365 African-Americans in the study, individuals had as little as 1 percent West African ancestry and as much as 99 percent.
There are significant implications for pharmacogenomic studies and assessment of disease risk.
It appears that the range of genetic ancestry captured under the term African-American is extremely diverse, suggesting that caution should be used in prescribing treatment based on differential guidelines for African-Americans.
"We were able to distinguish among closely related West African populations and showed that genetically inferred ancestry correlates strongly with geography and language, reflecting historic migration events in Africa," said Tishkoff.
"We were also able to show that there is little genetic differentiation among African-Americans in the African portion of their ancestry, reflecting the fact that most African-Americans have ancestry from several regions of western Africa," she said.
"The greatest variation among African-Americans is in their proportion of European ancestry, which has important implications for the design of personalized medical treatments," she added.