Technique will likely have applications in forensic science and donor organ monitoring
Researchers at Johns Hopkins have identified a highly sensitive means of analyzing very tiny amounts of DNA. The discovery, they say, could increase the ability of forensic scientists to match genetic material in some criminal investigations. It could also prevent the need for a painful, invasive test given to transplant patients at risk of rejecting their donor organs and replace it with a blood test that reveals traces of donor DNA.
In a report in the September issue of The Journal of Molecular Diagnostics, the research team says laboratory tests already show that the new analytical method compares favorably with a widely used DNA comparison technique. The researchers have applied for a patent.
The current method for comparing DNA to determine paternity and advance criminal investigations counts the number of repeats in certain highly repetitive blocks of DNA that are not part of genes. But, says James Eshleman, M.D., Ph.D., a professor of pathology at the Johns Hopkins University School of Medicine, "Repeat testing will only detect DNA that makes up at least 1 percent of a DNA sample, so it's not great for situations in which results depend on small amounts of material within a larger sample."
Making comparisons based on common "point mutations," or variations within actual genes, was long considered impractical because of the high costs of DNA sequence testing. But the cost of sequencing has fallen so low in recent years that Eshleman's team revisited the idea.
Choosing a block of DNA with 17 common point mutations in close proximity along the genome, Marija Debeljak, a technician in Eshleman's laboratory, looked for mismatches in various mixtures of lab-grown human cells. "We could detect cells when they made up just .01 percent of the mixture, which is a big improvement over the current method, which can only detect DNA that makes up 1 to 5 percent of a sample," Eshleman says.
In addition to forensic and paternity testing applications, the new method could also potentially be used to monitor the health of bone marrow transplant patients, Eshleman says. Testing transplant patients' blood for low levels of leukemia blood cells could theoretically be used as an early warning system, but current analysis based on the standard repeat testing is not sensitive enough to detect low levels of recurring leukemia DNA in blood.
In contrast, when the researchers tested bone marrow recipients' blood with their new system, they found that it could detect patient DNA. "If we're able to develop this test for commercial use, it could also free some solid-organ transplant recipients of the invasive biopsies that are currently used if rejection is suspected," Eshleman says.
Other authors on the paper were Donald N. Freed, Jane A. Welch, Lisa Haley, Katie Beierl, Brian S. Iglehart, Aparna Pallavajjalla, Christopher D. Gocke, Mary S. Leffell, Ming-Tseh Lin, Jonathan Pevsner and Sarah J. Wheelan, all of The Johns Hopkins University.
This study was funded by the Sol Goldman Foundation.
Read the article in The Journal of Molecular Diagnostics.
Read "Johns Hopkins Team Designs SNP-based Haplotype Method for Human Identity Testing" on GenomeWeb.
Read "Sequencing Cancer Mutations - There's an App For That."
Read "Hopkins Scientists Create Method to Personalize Chemotherapy Drug Selection."
Shawna Williams | Eurek Alert!
Gene therapy shows promise for treating Niemann-Pick disease type C1
27.10.2016 | NIH/National Human Genome Research Institute
'Neighbor maps' reveal the genome's 3-D shape
27.10.2016 | International School of Advanced Studies (SISSA)
Ultrafast lasers have introduced new possibilities in engraving ultrafine structures, and scientists are now also investigating how to use them to etch microstructures into thin glass. There are possible applications in analytics (lab on a chip) and especially in electronics and the consumer sector, where great interest has been shown.
This new method was born of a surprising phenomenon: irradiating glass in a particular way with an ultrafast laser has the effect of making the glass up to a...
Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion
Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...
Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.
"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...
In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.
A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...
By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.
"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...
14.10.2016 | Event News
14.10.2016 | Event News
12.10.2016 | Event News
27.10.2016 | Materials Sciences
27.10.2016 | Physics and Astronomy
27.10.2016 | Life Sciences