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Genetic studies link indigenous peoples in the Amazon and Australasia

Native Americans living in the Amazon bear an unexpected genetic connection to indigenous people in Australasia, suggesting a previously unknown wave of migration to the Americas thousands of years ago, a new study has found.

“It’s incredibly surprising,” said David Reich, Harvard Medical School professor of genetics and senior author of the study. “There’s a strong working model in archaeology and genetics, of which I have been a proponent, that most Native Americans today extend from a single pulse of expansion south of the ice sheets–and that’s wrong. We missed something very important in the original data.”

Previous research had shown that Native Americans from the Arctic to the southern tip of South America can trace their ancestry to a single “founding population” called the First Americans, who came across the Bering land bridge about 15,000 years ago. In 2012, Reich and colleagues enriched this history by showing that certain indigenous groups in northern Canada inherited DNA from at least two subsequent waves of migration.

The new study, published July 21 in Nature, indicates that there’s more to the story.

Pontus Skoglund, first author of the paper and a postdoctoral researcher in the Reich lab, was studying genetic data gathered as part of the 2012 study when he noticed a strange similarity between one or two Native American groups in Brazil and indigenous groups in Australia, New Guinea and the Andaman Islands.

“That was an unexpected and somewhat confusing result,” said Reich, who is also an associate member of the Broad Institute of Harvard and MIT and a Howard Hughes Medical Investigator. “We spent a really long time trying to make this result go away and it just got stronger.”

Skoglund and colleagues from HMS, the Broad and several universities in Brazil analyzed publicly available genetic information from 21 Native American populations from Central and South America. They also collected and analyzed DNA from nine additional populations in Brazil to make sure the link they saw hadn’t been an artifact of how the first set of genomes had been collected. The team then compared those genomes to the genomes of people from about 200 non-American populations.

The link persisted. The Tupí-speaking Suruí and Karitiana and the Ge-speaking Xavante of the Amazon had a genetic ancestor more closely related to indigenous Australasians than to any other present-day population. This ancestor doesn’t appear to have left measurable traces in other Native American groups in South, Central or North America.

The genetic markers from this ancestor don’t match any population known to have contributed ancestry to Native Americans, and the geographic pattern can’t be explained by post-Columbian European, African or Polynesian mixture with Native Americans, the authors said. They believe the ancestry is much older–perhaps as old as the First Americans.

In the ensuing millennia, the ancestral group has disappeared.

“We’ve done a lot of sampling in East Asia and nobody looks like this,” said Skoglund. “It’s an unknown group that doesn’t exist anymore.”

The team named the mysterious ancestor Population Y, after the Tupí word for ancestor, “Ypykuéra.”

Reich, Skoglund and colleagues propose that Population Y and First Americans came down from the ice sheets to become the two founding populations of the Americas.

“We don’t know the order, the time separation or the geographical patterns,” said Skoglund.

Researchers do know that the DNA of First Americans looked similar to that of Native Americans today. Population Y is more of a mystery.

“About 2 percent of the ancestry of Amazonians today comes from this Australasian lineage that’s not present in the same way elsewhere in the Americas,” said Reich.

However, that doesn’t establish how much of their ancestry comes from Population Y. If Population Y were 100 percent Australasian, that would indeed mean they contributed 2 percent of the DNA of today’s Amazonians. But if Population Y mixed with other groups such as the First Americans before they reached the Americas, the amount of DNA they contributed to today’s Amazonians could be much higher–up to 85 percent.

To answer that question, researchers would need to sample DNA from the remains of a person who belonged to Population Y. Such DNA hasn’t been obtained yet. One place to look might be in the skeletons of early Native Americans whose skulls some researchers say have Australasian features. The majority of these skeletons were found in Brazil.

Reich and Skoglund think that some of the most interesting open questions about Native American population history are about the relationships among groups after the initial migrations.

“We have a broad view of the deep origins of Native American ancestry, but within that diversity we know very little about the history of how those populations relate to each other,” said Reich.

This work was supported by the National Science Foundation (HOMINID grant BCS-1032255), the National Institutes of Health (GM100233), the Simons Foundation (grant 280376), the Howard Hughes Medical Institute, the Conselho Nacional de Desenvolvimento Científico e Tecnológico and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (Brazil), the Wenner-Gren Foundation and the Swedish Research Council (VR grant 2014-453).

Native Americans living in the Amazon bear an unexpected genetic connection to indigenous people in Australasia, suggesting a previously unknown wave of migration to the Americas thousands of years ago, a new study has found.

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Carrier screening through Amazon? Good Start Genetics expands its online presence

Selling physician-ordered carrier screening kits on Amazon may not seem like a logical fit, but there are a number of benefits that Good Start Genetics is now tapping into.

What can’t you buy on Amazon these days?

Unfortunately for brick and mortar stores, the online retail giant continues to expand at a voracious pace, underscored by the recent addition of prescription carrier screening tests.

The tests belong to Good Start Genetics, a Cambridge, Massachusetts-based company that first partnered with Amazon in November 2016.

Good Start is part of a growing class of companies that use next-generation sequencing to understand a couples’ risk of passing a genetic condition to future offspring. Depending on the results, families can choose alternative pregnancy options, adoption, or simply prepare better for a possible disability.

The idea of selling the kit on Amazon highlights the intriguing sales logistics. As with other genetic tests, the results can have profound consequences. They’re also difficult for laypeople to fully understand. For this reason, the tests remain physician-ordered only and Good Start offers free access to board-certified genetic counselors alongside its kits.

To date, the only product available was VeriYou, a saliva-based test that screens for cystic fibrosis (CF) and spinal muscular atrophy (SMA) — two of the most common inherited genetic disorders. Approximately 1 in every 19 Americans carries one of these mutations. If both parents are affected, their offspring have a 25 percent chance of inheriting the disorder.

Consumers that purchase VeriYou are sent instructions for registering the test online. The process requires a rundown of the person’s family history and consent information. A licensed physician will then review and order the test, if appropriate.

It doesn’t seem a natural fit for Amazon, but the pseudo-direct-to-consumer approach confers a number of benefits. It differentiates Good Start’s tests in a crowded market and normalizes the idea of carrier screening. It also provides transparency into the process and the total out-of-pocket cost.

And, as the company noted in the November media release, “Good Start is positioned to offer its physician-ordered genetic tests to couples at the right time, based on life stage insights from Amazon.” In other words, if you’re buying prenatal supplements on Amazon, there’s a chance you’ll see Good Start’s ad appear.

With the proof-of-concept complete, the company has now announced plans to expand its Amazon offering, adding the VeriYou AJ/SMA test to the catalog. It screens for SMA and the 17 most prevalent genetic disorders in the Ashkenazi Jewish population.

Given the evolution of patient-centric healthcare – and the dominance of Amazon – it was likely just a matter of time. A recent report by the Institute for Local Self-Reliance (ILSR) estimates that Amazon captured 46 percent of all online spending in 2016.

“Healthcare is rapidly changing in a way that enables new delivery models in reproductive health that broaden access and affordability for millions,” said Jeffrey Luber , Good Start’s president and CEO in a company statement. “Central to our commitment to responsible testing, is our inclusion of physician ordering and world-class genetic counseling with every test, and at price points not previously seen in the market.”

Despite its best efforts, some barriers will always remain. Even today, many pregnancies are unplanned. The CDC cites statistics from 2006, which found 49 percent of pregnancies were unintentional. That leaves a lot less room for carrier screening, even when you’re tracking purchasing decisions.

Photo: vasabii, Getty Images

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Selling physician-ordered carrier screening kits on Amazon may not seem like a logical fit, but there are a number of benefits that Good Start Genetics is now tapping into.