As a proof of concept in one of their experiments, the researchers scooped a soda can-sized water sample from a creek in St. Augustine, Fla. They then fed the sample’s genetic material through a nanopore sequencer, allowing 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 readable human DNA than they expected. And as knowledge about human genetics increases, analysis of even limited samples can yield a wealth of information.
The researchers recovered enough mitochondrial DNA — passed down directly from mother to child through thousands of generations — to create a snapshot of the genetic ancestry of the population around the creek, which roughly matches 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 that have been shown to carry a higher risk of diabetes, heart problems or various eye diseases. According to their records, someone whose genetic material showed up in the sample had a mutation that could lead to a rare disease that causes progressive neurological impairment and is often fatal. The disease is hereditary and may not appear until a patient is 40. Dr. Duffy wondered: Does that person know? Does the person’s family have? Does the person’s insurance company?
Surveillance and forensics
Anna Lewis, a Harvard researcher who studies the ethical, legal and social implications of genetic research, said environmental DNA was not widely discussed by experts in bioethics. But after the findings of Dr. Duffy and his colleagues must be.
Technology focused on eDNA, she said, could be used for certain types of surveillance of people – for example, people with specific ancestral backgrounds or with certain medical conditions or disabilities.
Researchers agree that the implications of such use depend on who is using the technology and why. While pooled eDNA samples can help public health researchers determine the incidence of a disease-causing mutation in a community, that same eDNA sample can also be used to track down and prosecute ethnic minorities.
