As a proof of concept in one of their experiments, the researchers scooped up a soda-can-size sample of water from a creek in St. Augustine, Fla. They then fed the genetic material from the sample through a nanopore sequencer, which allows researchers to read longer stretches of DNA. The one they used cost about $1000, is the size of a cigarette lighter and plugs into a laptop like a flash drive.
From the samples, the team recovered much more legible human DNA than they had anticipated. And as knowledge expands about human genetics, analysis of even limited samples can reveal a wealth of information.
The researchers recovered enough mitochondrial DNA — passed directly from mother to child for thousands of generations — to generate a snapshot of the genetic ancestry of the population around the creek, which roughly aligns with the racial makeup reported in the latest census data for the area (although the researchers note that racial identity is a poor proxy for genetic ancestry). One mitochondrial sample was even complete enough to meet the requirements for the federal missing persons database.
They also found key mutations shown to carry a higher risk of diabetes, cardiac issues or several eye diseases. According to their data, someone whose genetic material turned up in the sample had a mutation that could lead to a rare disease that causes progressive neurological impairment and is often fatal. The illness is hereditary and may not emerge until a patient’s 40s. Dr. Duffy couldn’t help but wonder — does that person know? Does the person’s family? Does the person’s insurance company?
Surveillance and forensics
Anna Lewis, a Harvard researcher who studies the ethical, legal and social implications of genetics research, said that environmental DNA hadn’t been widely discussed by experts in bioethics. But after the findings from Dr. Duffy and his colleagues, it will be.
Technology focused on eDNA, she said, could be used for surveillance of certain kinds of people — for example, people with a specific ancestral background or with particular medical conditions or disabilities.
The implications of such uses, researchers agree, depend on who is using the technology and why. While pooled eDNA samples could help public health researchers determine the incidence of a mutation that causes a disease in a community, that same eDNA sample could equally be used to find and persecute ethnic minorities.