Findings could lead to new clinical laboratory tests to screen for individuals with increased risk of blood transfusion complications
Pathologists and clinical laboratory scientists who understand the complexities of blood typing from one human to another will be interested to learn that a 50 year-old mystery has brought about an exciting new discovery—a new human blood group.
British and Israeli scientists led by the UK’s NHS Blood and Transplant (NHSBT) and the University of Bristol discovered the meaning behind a missing protein molecule found in a pregnant woman five decades ago. This anomaly has now been given its own blood group identification called MAL, according to a University of Bristol new release.
“Some people can lack this blood group due to the effect of illness, but the rare inherited form of the AnWj-negative phenotype has only been found in a handful of individuals—though due to this discovery it will now be easier to find others in the future,” the news release notes.
This is important because receiving mismatched blood can be fatal.
“AnWj is a high-prevalence red blood cell (RBC) antigen in the ISBT 901 series. Only nine reports of anti-AnWj have been published since it was first documented in 1972,” according to a 2012 article published by the American Association of Blood Banks, now known as the Association for the Advancement of Blood and Biotherapies (AABB).
For even the small proportion of the population with this new blood group, diagnosing its presence can have a major impact while preventing unwanted harm.
“The work was difficult because the genetic cases are very rare. We would not have achieved this without exome sequencing, as the gene we identified wasn’t an obvious candidate and little is known about Mal protein in red cells,” said Louise Tilley, PhD, Senior Research Scientist, IBGRL Red Cell Reference at NHS Blood and Transplant, in the news release.
“The genetic background of AnWj has been a mystery for more than 50 years, and one which I personally have been trying to resolve for almost 20 years of my career,” said Louise Tilley, PhD (above), Senior Research Scientist, IBGRL Red Cell Reference at NHS Blood and Transplant, in the news release. “It represents a huge achievement, and the culmination of a long term effort, to finally establish this new blood group system and be able to offer the best care to rare, but important, patients,” she added. Clinical laboratory scientists involved in blood banking will want to keep updated as further research into this new blood group is published. (Photo copyright: NHS Blood and Transplant.)
Unraveling the Mystery
In 1972, scientists were stumped by a pregnant woman with a blood sample that was “mysteriously missing a surface molecule found on all other known red blood cells at the time,” Science Alert reported. The AnWj antigen that was missing in that patient’s blood is present in 99.9% of human blood samples.
“Researchers found that the AnWj antigen is carried on the Mal protein. While illness can cause some people to lose the AnWj antigen, inherited cases of the AnWj-negative phenotype are extremely rare. Using whole exome sequencing on five genetically AnWj-negative individuals, researchers confirmed that, in these cases, the participants lacked the antigen due to homozygous deletions in the MAL gene,” an AABB news release stated.
The researchers named the group with the missing antigen the MAL blood group (short for Myelin and Lymphocyte Protein) which is where the antigen resides.
Genetic sequencing enabled the scientists to locate the gene when they “inserted the normal MAL gene into blood cells that were AnWj-negative. This effectively delivered the AnWj antigen to those cells,” Science Alert noted.
Mutated MAL genes result in the AnWj-negative blood type. The team discovered three patients with the blood type and no mutation, “Suggesting that sometimes blood disorders can also cause the antigen to be suppressed,” Science Alert added. The researchers also discovered that AnWj isn’t present in newborns but arrives sometime after they are born.
“Interestingly, all the AnWj-negative patients included in the study shared the same mutation. However, no other cell abnormalities or diseases were found to be associated with this mutation,” Science Alert said.
The discovery that “the Mal protein is responsible for binding AnWj antibodies” could lead to new clinical laboratory tests to screen for patients at risk from blood transfusions, AABB noted in its news release.
Facing the Challenge
Scientists had to overcome many challenges to uncover the details of this blood type. The complexity of the protein further hindered their efforts.
“MAL is a very small protein with some interesting properties which made it difficult to identify, and this meant we needed to pursue multiple lines of investigation to accumulate the proof we needed to establish this blood group system,” said Tim Satchwell, PhD, senior lecturer and cell biologist at the University of the West of England, in the University of Bristol news release.
“Resolving the genetic basis for AnWj has been one of our most challenging projects,” Nicole Thornton, head of IBGRL Red Cell Reference at NHSBT told the AABB. “There is so much work that goes into proving that a gene does actually encode a blood group antigen, but it is what we are passionate about, making these discoveries for the benefit of rare patients around the world.”
It’s hard to pinpoint how many individuals will benefit by testing for the blood group, Tilley told the BBC. Nevertheless, “the NHSBT is the last resort for about 400 patients across the world each year,” the BBC reported.
While more research needs to be done, the initial discovery is promising and may lead to new clinical laboratory tests to identify individuals who could be severely harmed should they receive the wrong blood type during a transfusion.
But even though the College of American Pathologists (CAP) and nine other organizations signed a December 12 stakeholder letter to leaders of key House and Senate committees urging passage of legislation that would enable some regulation of LDTs, the VALID Act was ultimately omitted from the year-end omnibus spending bill (H.R. 2617).
That may be due to pressure from organizations representing clinical laboratories and pathologists which lobbied hard against the bill.
Responding to criticism of its stance on FDA oversight of LDTs, in a May 2022 open letter posted on the organization’s website, anatomic pathologist and CAP president Emily Volk, MD, said “we at the CAP have an honest difference of opinion with some other respected laboratory organizations. … We believe the VALID Act is the only viable piece of legislation addressing the LDT issue. … the VALID Act contains many provisions that are similar to policy the CAP has advocated for regarding the regulation of laboratory tests since 2009. Importantly, the current version includes explicit protections for pathologists and our ability to practice medicine without infringement from the Food and Drug Administration (FDA).” (Photo copyright: College of American Pathologists.)
Organizations on Both Sides Brought Pressure to Bear on Legislators
The AAMC and AMP were especially influential, Bucshon told ProPublica. In addition to spending hefty sums on lobbying, AMP urged its members to contact legislators directly and provided talking points, ProPublica reported.
“The academic medical centers and big medical centers are in every state,” Bucshon said. As major employers in many locales, they have “a pretty big voice,” he added.
Discussing CAP’s reasoning behind its support of the VALID Act in a May 26 open letter and podcast, CAP president Emily Volk, MD, said the Valid Act “creates a risk-based system of oversight utilizing three tiers—low, moderate and high risk—in order to target the attention of the FDA oversight.”
While acknowledging that it had room for improvement, she lauded the bill’s three-tier risk-based system, in which tests deemed to have the greatest risks would receive the highest level of scrutiny.
She also noted that the bill exempts existing LDTs from an FDA premarket review “unless there is a safety concern for patients.” It would also exempt “low-volume tests, modified tests, manual interpretation tests, and humanitarian tests,” she wrote.
In addition, the bill would “direct the FDA not to create regulations that are duplicative of regulation under CLIA,” she noted, and “would require the FDA to conduct public hearings on LDT oversight.”
Pros and Cons of the VALID Act
One concern raised by opponents relates to how the VALID Act addressed user fees paid by clinical laboratories to fund FDA compliance activities. But Volk wrote that any specific fees “would need to be approved by Congress in a future FDA user fee authorization bill after years of public input.”
During the May 2022 podcast, Volk also cast CAP’s support as a matter of recognizing political realities.
“We understand that support for FDA oversight of laboratory-developed tests or IVCTs is present on both sides of the aisle and in both houses of Congress,” she said. “In fact, it enjoys wide support among very influential patient advocacy groups.” These groups “are very sophisticated in their understanding of the issues with laboratory-developed tests, and they do have the ear of Congress. There are many in the laboratory community that believe the VALID Act goes too far, but I can tell you that many of these patient groups don’t believe it goes far enough and are actively pushing for even more restrictive paradigms.”
Also urging passage of the bill were former FDA commissioners Scott Gottlieb, MD, and Mark B. McClellan, MD, PhD. In a Dec. 5 opinion piece for STAT, they noted that “diagnostic technologies have undergone considerable advances in recent decades, owing to innovation in fields like genomics, proteomics, and data science.” However, they wrote, laws governing FDA oversight “have not kept pace,” placing the agency in a position of regulating tests based on where they are made—in a medical laboratory or by a manufacturer—instead of their “distinctive complexity or potential risks.”
In their May 22 letter, opponents of the legislation outlined broad areas of concern. They contended that it would create “an onerous and complex system that would radically alter the way that laboratory testing is regulated to the detriment of patient care.” And even though existing tests would be largely exempted from oversight, “the utility of these tests would diminish over time as the VALID Act puts overly restrictive constraints on how they can be modified.”
CLIA Regulation of LDTs also Under Scrutiny
The provision to avoid duplication with the Clinical Laboratory Improvement Amendments (CLIA) program—which currently has some regulatory oversight of LDTs and IVCTs—is “insufficient,” opponents added, “especially when other aspects of the legislation call for requirements and activities that lead to duplicative and unnecessary regulatory burden.”
Opponents to the VALID Act also argued that the definitions of high-, medium-, and low-risk test categories lacked clarity, stating that “the newly created definition of moderate risk appears to overlap with the definition of high risk.”
The opponents also took issue with the degree of discretion that the bill grants to the US Secretary of Health and Human Services. This will create “an unpredictable regulatory process and ambiguities in the significance of the policy,” they wrote, while urging the Senate committee to “narrow the discretion so that stakeholders may better evaluate and understand the implications of this legislation.”
Decades ago, clinical laboratory researchers were allowed to develop assays in tandem with clinicians that were intended to provide accurate diagnoses, earlier detection of disease, and help guide selection of therapies. Since the 1990s, however, an industry of investor-funded laboratory companies have brought proprietary LDTs to the national market. Many recognize that this falls outside the government’s original intent for encouragement of laboratory-developed tests to begin with.
VCU scientists used the technique to measure mutations associated with acute myeloid leukemia, potentially offering an attractive alternative to DNA sequencing
More accurate but less-costly cancer diagnostics are the Holy Grail of cancer research. Now, research scientists at Virginia Commonwealth University (VCU) say they have developed a clinical laboratory diagnostic technique that could be far cheaper and more capable than standard DNA sequencing in diagnosing some diseases. Their method combines digital polymerase chain reaction (dPCR) technology with high-speed atomic force microscopy (HS-AFM) to generate nanoscale-resolution images of DNA.
The technique allows the researchers to measure polymorphisms—variations in gene lengths—that are associated with many cancers and neurological diseases. The VCU scientists say the new technique costs less than $1 to scan each dPCR reaction.
“We chose to focus on FLT3 mutations because they are difficult to [diagnose], and the standard assay is limited in capability,” said physicist Jason Reed, PhD, Assistant Professor in the Virginia Commonwealth University Department of Physics, in a VCU press release.
Reed is an expert in nanotechnology as it relates to biology and medicine. He led a team that included other researchers in VCU’s physics department as well as physicians from VCU Massey Cancer Center and the Department of Internal Medicine at VCU School of Medicine.
“The technology needed to detect DNA sequence rearrangements is expensive and limited in availability, yet medicine increasingly relies on the information it provides to accurately diagnose and treat cancers and many other diseases,” said Jason Reed, PhD (above center, with Andrey Mikheikin, PhD, on left and Sean Koebley, PhD, on right), in a press release from Virginia Commonwealth University (VCU). “We’ve developed a system that combines a routine laboratory process with an inexpensive yet powerful atomic microscope that provides many benefits over standard DNA sequencing for this application, at a fraction of the cost.” (Photo copyright: Virginia Commonwealth University.)
Validating the Clinical Laboratory Test
The physicists worked with two VCU physicians—hematologist/oncologist Amir Toor, MD, and hematopathologist Alden Chesney, MD—to compare the imaging technique to the LeukoStrat CDx FLT3 Mutation Assay, which they described as the “current gold standard test” for diagnosing FLT3 gene mutations.
The researchers said their technique matched the results of the LeukoStrat test in diagnosing the mutations. But unlike that test, the new technique also can measure variant allele frequency (VAL). This “can show whether the mutation is inherited and allows the detection of mutations that could potentially be missed by the current test,” states the VCU press release.
“We plan to continue developing and testing this technology in other diseases involving DNA structural mutations,” Reed said. “We hope it can be a powerful and cost-effective tool for doctors around the world treating cancer and other devastating diseases driven by DNA mutations.”
“In our approach we first used digital PCR, in which a mixed sample is diluted to less than one target molecule per aliquot and the aliquots are amplified to yield homogeneous populations of amplicons,” he said. “Then, we deposited each population onto an atomically-flat partitioned surface.”
The VCU researchers “scanned each partition with high-speed atomic force microscopy, in which an extremely sharp tip is rastered across the surface, returning a 3D map of the surface with nanoscale resolution,” he said. “We wrote code that traced the length of each imaged DNA molecule, and the distribution of lengths was used to determine whether the aliquot was a wild type [unmutated] or variant.”
In Diagnostics World, Reed said the method “doesn’t really have any more complexity than a PCR assay itself. It can easily be done by most lab technicians.”
Earlier Research
A VCU press release from 2017 noted that Reed’s research team had developed technology that uses optical lasers (similar to those in a DVD player) to accelerate the scanning. The researchers previously published a study about the technique in Nature Communications, and a patent is currently pending.
“DNA sequencing is a powerful tool, but it is still quite expensive and has several technological and functional limitations that make it difficult to map large areas of the genome efficiently and accurately,” Reed said in the 2017 VCU press release. “Our approach bridges the gap between DNA sequencing and other physical mapping techniques that lack resolution. It can be used as a stand-alone method or it can complement DNA sequencing by reducing complexity and error when piecing together the small bits of genome analyzed during the sequencing process.”
Using CRISPR technology, the team also developed what they described as a “chemical barcoding solution,” placing markers on DNA molecules to identify genetic mutations.
New DNA Clinical Laboratory Testing?
Cancer diagnostics are constantly evolving and improving. It is not clear how long it will be before VCU’s new technique will reach clinical laboratories that perform DNA testing, if at all. But VCU’s new technique is intriguing, and should it prove viable for clinical diagnostic use it could revolutionize cancer diagnosis. It is a development worth watching.
