An Identifying Allele Found Among All Native American populations

A recent study by has characterized an allele that is present in all Native American populations tested. The allele, 9RA (9 repeat-allele) is a 9 tetranucleotide repeat allele composed of 275 bp at autosomal (meaning non-sex chromosome) microsatellite locus D9S1120 (on chromosome 9). Microsatellites are small DNA repeats that are typically neutral and are often used as molecular markers for population studies. According to the report, 9RA was found at an average percentage of roughly 30% among all the populations.

Although 9RA was found among Chukchi and the Koryaks of Western Beringia (on the eastern edge of Siberia), the allele was not identified in the large number of Asian populations tested (perhaps because this is a mutation that arose in populations as they approached the land bridge or because the sample size was not big enough to detect it).

The study has larger implications for migration theory. One of the prevailing migration theories is the three-wave hypothesis which proposes that the Na-Dene, Aleut-Eskimo, and Amerind groups migrated into the Americas in three separate waves. This theory, from Joseph Greenberg, is based on linguistic studies of the three language groups. The ubiquitous presence of the 9RA allele among all three groups suggests that a single founding population contributed a large percentage of ancestry to all Native American populations. That single population was most likely located in the eastern portion of Siberia just before the crossing over the Bering land bridge.

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