Palmetto GBA’s Chief Medical Officer will cover how clinical laboratories billing for genetic testing should prepare for Z-Codes at the upcoming Executive War College in New Orleans
After multiple delays, UnitedHealthcare (UHC) commercial plans will soon require clinical laboratories to use Z-Codes when submitting claims for certain molecular diagnostic tests. Several private insurers, including UHC, already require use of Z-Codes in their Medicare Advantage plans, but beginning June 1, UHC will be the first to mandate use of the codes in its commercial plans as well. Molecular, anatomic, and clinical pathologist Gabriel Bien-Willner, MD, PhD, who oversees the coding system and is Chief Medical Officer at Palmetto GBA, expects that other private payers will follow.
“A Z-Code is a random string of characters that’s used, like a barcode, to identify a specific service by a specific lab,” Bien-Willner explained in an interview with Dark Daily. By themselves, he said, the codes don’t have much value. Their utility comes from the DEX Diagnostics Exchange registry, “where the code defines a specific genetic test and everything associated with it: The lab that is performing the test. The test’s intended use. The analytes that are being measured.”
The registry also contains qualitative information, such as, “Is this a good test? Is it reasonable and necessary?” he said.
Molecular, anatomic, and clinical pathologist Gabriel Bien-Willner, MD, PhD (above), Palmetto GBA’s Chief Medical Officer, will speak about Z-Codes and the MolDX program during several sessions at the upcoming Executive War College on Diagnostics, Clinical Laboratory, and Pathology Management taking place in New Orleans on April 30-May 1. Clinical laboratories involved in genetic testing will want to attend these critical sessions. (Photo copyright: Bien-Willner Physicians Association.)
Palmetto GBA Takes Control
Palmetto’s involvement with Z-Codes goes back to 2011, when the company established the MolDX program on behalf of the federal Centers for Medicare and Medicaid Services (CMS). The purpose was to handle processing of Medicare claims involving genetic tests. The coding system was originally developed by McKesson, and Palmetto adopted it as a more granular way to track use of the tests.
In 2017, McKesson merged its information technology business with Change Healthcare Holdings LLC to form Change Healthcare. Palmetto GBA acquired the Z-Codes and DEX registry from Change in 2020. Palmetto GBA had already been using the codes in MolDX and “we felt we needed better control of our own operations,” Bien-Willner explained.
In addition to administering MolDX, Palmetto is one of four regional Medicare contractors who require Z-Codes in claims for genetic tests. Collectively, the contractors handle Medicare claims submissions in 28 states.
Benefits of Z-Codes
Why require use of Z-Codes? Bien-Willner explained that the system addresses several fundamental issues with molecular diagnostic testing.
“Payers interact with labs through claims,” he said. “A claim will often have a CPT code [Current Procedural Technology code] that doesn’t really explain what was done or why.”
In addition, “molecular diagnostic testing is mostly done with laboratory developed tests (LDTs), not FDA-approved tests,” he said. “We don’t see LDTs as a problem, but there’s no standardization of the services. Two services could be described similarly, or with the same CPT codes. But they could have different intended uses with different levels of sophistication and different methodologies, quality, and content. So, how does the payer know what they’re paying for and whether it’s any good?”
When the CPT code is accompanied by a Z-Code, he said, “now we know exactly what test was done, who did it, who’s authorized to do it, what analytes are measured, and whether it meets coverage criteria under policy.”
The process to obtain a code begins when the lab registers for the DEX system, he explained. “Then they submit information about the test. They describe the intended use, the analytes that are being measured, and the methodologies. When they’ve submitted all the necessary information, we give the test a Z-Code.”
The assessment could be as simple as a spreadsheet that asks the lab which cancer types were tested in validation, he said. On the other end of the scale, “we might want to see the entire validation summary documentation,” he said.
Commercial Potential
Bien-Willner joined the Palmetto GBA in 2018 primarily to direct the MolDX program. But he soon saw the potential use of Z-Codes and the DEX registry for commercial plans. “It became instantly obvious that this is a problem for all payers, not just Medicare,” he said.
Over time, he said, “we’ve refined these processes to make them more reproducible, scalable, and efficient. Now commercial plans can license the DEX system, which Z-Codes are a part of, to better automate claims processing or pre-authorizations.”
In 2021, the company began offering the coding system for Medicare Advantage plans, with UHC the first to come aboard. “It was much easier to roll this out for Medicare Advantage, because those programs have to follow the same policies that Medicare does,” he explained.
As for UHC’s commercial plans, the insurer originally planned to require Z-Codes in claims beginning Aug. 1, 2023, then pushed that back to Oct. 1, according to Dark Daily’s sister publication The Dark Report.
Then it was pushed back again to April 1 of this year, and now to June 1.
“The implementation will be in a stepwise fashion,” Bien-Willner advised. “It’s difficult to take an entirely different approach to claims processing. There are something like 10 switches that have to be turned on for everything to work, and it’s going to be one switch at a time.”
For Palmetto GBA, the commercial plans represent “a whole different line of business that I think will have a huge impact in this industry,” he said. “They have the same issues that Medicare has. But for Medicare, we had to create automated solutions up front because it’s more of a pay and chase model,” where the claim is paid and CMS later goes after errors or fraudulent claims.
“Commercial plans in general just thought they could manually solve this issue on a claim-by-claim basis,” he said. “That worked well when there was just a handful of genetic tests. Now there are tens of thousands of tests and it’s impossible to keep up.
They instituted programs to try to control these things, but I don’t believe they work very well.”
Bien-Willner is scheduled to speak about Palmetto GBA’s MolDX program, Z-Codes, and related topics during three sessions at the upcoming 29th annual Executive War College conference. Clinical laboratory and pathology group managers would be wise to attend his presentations. Visit here (or paste this URL into your browser: https://www.executivewarcollege.com/registration) to learn more and to secure your seat in New Orleans.
Clinical laboratories and pathology groups may soon have new assays for diagnosis, treatment identification, patient monitoring
It’s here at last! The human Y chromosome now has a full and complete sequence. This achievement by an international team of genetic researchers is expected to open the door to significant insights in how variants and mutations in the Y chromosome are involved in various diseases and health conditions. In turn, these insights could lead to new diagnostic assays for use by clinical laboratories and pathology groups.
Pathologists and clinical laboratories involved in genetic research will understand the significance of this accomplishment. The full Y chromosome sequence “fills in gaps across more than 50% of the Y chromosome’s length, [and] uncovers important genomic features with implications for fertility, such as factors in sperm production,” SciTechDaily noted.
This breakthrough will make it possible for other research teams to gain further understanding of the functions of the Y chromosome and how specific gene variants and mutations contribute to specific health conditions and diseases. In turn, knowledge of those genetic sequences and mutations would give clinical laboratories the assays that help diagnosis, identify relevant therapies, and monitor a patient’s progress.
“When you find variation that you haven’t seen before, the hope is always that those genomic variants will be important for understanding human health,” said Adam Phillippy, PhD, a senior investigator and head of the Genome Informatics Section at the National Human Genome Research Institute, in a press release. Clinical laboratories and anatomic pathology groups may soon have new assays based on the T2T study findings. (Photo copyright: National Human Genome Research Institute.)
Study Background and Recognition
Revolutionary thinking by the Telomere-to-Telomere (T2T) scientists led to the team’s breakthrough. The researchers “applied new DNA sequencing technologies and sequence assembly methods, as well as knowledge gained from generating the first gapless sequences for the other 23 human chromosomes,” SciTechDaily reported.
In 1977, the first complete genome of an organism was sequenced. Thus began the commencement of sequencing technology research. Twenty years ago the first human genome sequence was completed. The result was thanks to years of work through the preferred “chain termination” (aka, Sanger Sequencing) method developed by Fred Sanger and a $2.7 billion contribution from the Human Genome Project, according to a study published in the African Journal of Laboratory Medicine (AJLM).
By 2005, a new era in genomic sequencing emerged. Scientists now employed a technique called pyrosequencing and the change had great benefits. “Massively parallel or next-generation sequencing (NGS) technologies eliminated the need for multiple personnel working on a genome by automating DNA cleavage, amplification, and parallel short-read sequencing on a single instrument, thereby lowering costs and increasing throughput,” the AJLM paper noted.
The new technique brought great results. “Next-generation sequencing technologies have made sequencing much easier, faster and cheaper than Sanger sequencing,” the AJLM study authors noted.
The changes allowed more sequencing to be completed. Nevertheless, more than half of the Y chromosome sequence was still unknown until the new findings from the T2T study, SciTechDaily reported.
Why the TDT Breakthrough Is So Important
“The biggest surprise was how organized the repeats are,” said Adam Phillippy, PhD, a senior investigator and head of the NHGRI. “We didn’t know what exactly made up the missing sequence. It could have been very chaotic, but instead, nearly half of the chromosome is made of alternating blocks of two specific repeating sequences known as satellite DNA. It makes a beautiful, quilt-like pattern.”
Much can be gained in knowing more about the Y chromosome. Along with the X chromosome, it is significant in sexual development. Additionally, current research is showing that genes on the Y chromosome are linked to the risk and severity of cancer.
Might What Comes Next Give Clinical Labs New Diagnostic Tools?
The variety of new regions of the Y chromosome that the T2T team discovered bring into focus several areas of new genetic research. For instance, the “azoospermia factor region, a stretch of DNA containing several genes known to be involved in sperm production” was uncovered, and “with the newly completed sequence, the researchers studied the structure of a set of inverted repeats or palindromes in the azoospermia factor region,” SciTechDaily reported.
“This structure is very important because occasionally these palindromes can create loops of DNA. Sometimes, these loops accidentally get cut off and create deletions in the genome,” said Arang Rhie, PhD, a staff scientist at NHGRI and first author of the Nature study.
Missing regions would challenge the production of sperm, impacting fertility, so being able to finally see a complete sequence will help research in this area.
Scientists are only just beginning to recognize the value of this breakthrough to future genetic research and development. As genetic sequencing costs continue to drop, the T2T research findings could mean new treatment options for pathologists and diagnostic assays for clinical laboratories are just around the corner.
From ‘new-school’ rules of running a clinical laboratory to pharmacy partnerships to leveraging lab data for diagnostics, key industry executives discussed the new era of clinical laboratory and pathology operations
Opening keynotes at the 28th Annual Executive War College on Diagnostics, Clinical Laboratory, and Pathology Management taking place in New Orleans this week covered three main forces that healthcare and medical laboratory administrators should be preparing to address: new consumer preferences, new care models, and new payment models.
“COVID-19 didn’t change a whole lot of things in one sense, but it accelerated a lot of trends that were already happening in healthcare,” said Robert L. Michel, Editor-in-Chief of Dark Daily and its sister publication The Dark Report, and Founder of the Executive War College, during his opening keynote address to a packed ballroom of conference attendees. “Healthcare is transforming, and the transformation is far more pervasive than most consumers appreciate.
“Disintermediation, for example, is taking traditional service providers and disrupting them in substantial ways, and if you think about the end of fee-for-service, be looking forward because your labs can be paid for the value you originate that makes a difference in patient care,” Michel added.
Another opportunity for clinical laboratories, according to Michel, is serving Medicare Advantage plans which have soared in enrollment. “Lab leaders should be studying Medicare Advantage for how to integrate Medicare Advantage incentives into their lab strategies,” he said, highlighting the new influence of risk adjustment models which use diagnostic data to predict health condition expenditures.
Opening sessions at this week’s annual Executive War College on Diagnostics, Clinical Laboratory, and Pathology Management, presented by Robert L. Michel (above), Editor-in-Chief of Dark Daily and its sister publication The Dark Report, discussed demand for delivering healthcare services—including medical laboratory testing—as consumer preferences evolve, new care models are designed, and as payers seek value over volume. While these three forces may be challenging at the outset, they also create opportunities for clinical laboratories and pathology groups—a focal point of the Executive War College each year. (Photo copyright: The Dark Intelligence Group.)
Medical Laboratories Must Adapt to ‘New-School’ Rules
During his keynote address, Stan Schofield, Vice President and Managing Principal at The Compass Group, noted that while the basic “old-school” rules of successfully running a clinical laboratory have not changed—e.g., adding clients, keeping clients, creating revenue opportunities, getting paid, and reducing expenses—the interpretation of each rule has changed. The Compass Group is a trade federation based in South Carolina that serves not-for-profit healthcare integrated delivery networks (IDNs), including 32 health systems and 600 hospitals.
Schofield advised that when it comes to adding new clients under the “new-school” rules of lab management, clinical laboratory directors must be aware of and adapt to hospital integrations of core labs, clinical integrations across health systems, seamless services, direct contracting with employers in insurance relationships, and direct-to-consumer testing. Keeping clients, Schofield said, involves five elements:
Strong customer service.
A tailored metrics program for quality services based on what is important to a lab’s clients.
Balanced scorecards that look at the business opportunity and value proposition with each client.
Monitoring patients’ experiences and continuous improvement.
Participation in all payer agreements.
As to the problem of commoditization of laboratory goods and services, Schofield said, “Right now, we’re facing the monetization of the laboratory. We’re going to swiftly move from commoditization to monetization to commercialization.”
Pharmacies Enter the Clinical Laboratory Market
In another forward looking keynote address, David Pope, PharmD, CDE, Chief Pharmacy Officer at OmniSYS, XiFin Pharmacy Solutions, discussed the “test to treat” trend which could bring clinical laboratories and pharmacies together in new partnerships.
Diagnostics and pharmacy now intersect, according to Pope. “Pharmacists are on the move, and they are true contender as a new provider for you,” he said. “An area of pharmacy that is dependent upon labs is specialty medications.”
Specialty medicines now account for 55% of prescription spending, up from 28% in 2011, driven by growth in auto-immune and oncology, Pope noted. Other examples include companion diagnostics required for targeted treatments pertaining to all major cancers, and new areas like thalassemia (inherited blood disorders), obesity, next-generation sequencing, and pharmacogenomics, in addition to routine testing such as liver function and complete blood count (CBC).
Federal legislation may soon recognize pharmacists as healthcare providers who will be trained to perform specific clinical services, Pope said. Some states already recognize pharmacists as providers, he noted, explaining that pharmacies need lab data for three primary reasons:
Service—Pharmacies can act as a referral source to clinical laboratories. When referring, pharmacies may need to communicate lab test results to patients or providers to coordinate care.
Value-based care—Pharmacies would draw on data to counsel, prescribe, and coordinate care for chronic disease management, among other services.
Diagnostics and pharmacogenetics—Specialty medication workflows require documented test results within a specific timeframe prior to dispensing.
Another point Pope made: Large pharmacies are seeking lab partners. Labs that can provide rapid turnaround time and good pricing on complex tests provide pharmacies with partnership opportunities.
Using AI to Create Patients’ ‘Digital Twins’ That Help Identify Disease and Improve Care
High-tech healthcare technology underlies many opportunities in the clinical laboratory and pathology market, as evidenced throughout the Executive War College’s 2023 curriculum. An ongoing challenge for labs, however, is how to produce the valuable datasets that all labs have the potential to generate.
“It feels like we’ve come so far,” explained Brad Bostic, CEO of hc1 during his keynote address. “We’ve got the internet. We’ve got the cloud. All of this is amazing, but in reality, we have this massive proliferation of data everywhere and it’s very difficult to know how to actually put that into use. And nobody’s generating more data than clinical laboratories.
“Every single interaction with a patient that generates data gives you this opportunity to create the idea of a ‘digital twin.’ That means that labs are creating a mathematical description of what a person’s state is and using that information to look at how providers can optimally diagnose and treat that person. Ultimately, it is bigger than just one person. It’s hundreds of millions of people that are generating all this data, and many of these people fall into similar cohorts.”
This digital twin opportunity is heavily fueled by medical laboratory testing, Bostic said, adding that labs need to be able to leverage artificial intelligence (AI) to:
“I recommend lab leaders sit down with their teams and any outside partners they trust and identify what are their lab’s goals,” Bostic stated. “Think about how this technology can advance a lab’s mission. Look at strategy holistically—everything from internal operations to how patient care is affected.”
Molecular probes designed to spot minute amounts of pathogens in biological samples may aid clinical laboratories’ speed-to-answer
Driven to find a better way to isolate minute samples of pathogens from among high-volumes of other biological organisms, researchers at Canada’s McMaster University in Hamilton, Ontario, have unveiled a bioinformatics algorithm which they claim shortens time-to-answer and speeds diagnosis of deadly diseases.
Two disease pathogens the researchers specifically targeted in their study are responsible for sepsis and SARS-CoV-2, the coronavirus causing COVID-19. Clinical laboratories would welcome a technology which both shortens time-to-answer and improves diagnostic accuracy, particularly for pathogens such as sepsis and SARS-CoV-2.
Their design of molecular probes that target the genomic sequences of specific pathogens can enable diagnosticians and clinical laboratories to spot extremely small amounts of viral and bacterial pathogens in patients’ biological samples, as well as in the environment and wildlife.
“There are thousands of bacterial pathogens and being able to determine which one is present in a patient’s blood sample could lead to the correct treatment faster when time is very important,” Zachery Dickson, a lead author of the study, told Brighter World. Dickson is a bioinformatics PhD candidate in the Department of Biology at McMaster University. “The probe makes identification much faster, meaning we could potentially save people who might otherwise die,” he added.
Sepsis is a life-threatening response to infection that leads to organ failure, tissue damage, and death in hospitals worldwide. According to Sepsis Alliance, about 30% of people diagnosed with severe sepsis will die without quick and proper treatment. Thus, a “shortcut” to identifying sepsis in its early stages may well save many lives, the McMaster researchers noted.
And COVID-19 has killed millions. Such a tool that identifies sepsis and SARS-CoV-2 in minute biological samples would be a boon to hospital medical laboratories worldwide.
“We currently need faster, cheaper, and more succinct ways to detect pathogens in human and environmental samples that democratize the hunt, and this pipeline does exactly that,” Hendrik Poinar, PhD (above), McMaster Professor of Anthropology and a lead author of the study, told Brighter World. Poinar is Director of the McMaster University Ancient DNA Center. Hospital medical laboratories could help save many lives if sepsis and COVID-19 could be detected earlier. (Graphic copyright: McMaster University.)
Is Bioinformatics ‘Shortcut’ Faster than PCR Testing?
The researchers say their probes enable a shortcut to detection—even in an infection’s early stages—by “targeting, isolating, and identifying the DNA sequences specifically and simultaneously.”
The probes’ design makes possible simultaneous targeted capture of diverse metagenomics targets, Biocompare explained.
But is it faster than PCR (polymerase chain reaction) testing?
The McMaster scientists were motivated by the “challenges of low signal, high background, and uncertain targets that plague many metagenomic sequencing efforts,” they noted in their paper.
They pointed to challenges posed by PCR testing, a popular technique used for detection of sepsis pathogens as well as, more recently, for SARS-CoV-2, the coronavirus causing COVID-19.
“The (PCR) technique relies on primers that bind to nucleic acid sequences specific to an organism or group of organisms. Although capable of sensitive, rapid detection and quantification of a particular target, PCR is limited when multiple loci are targeted by primers,” the researchers wrote in Cell Reports Methods.
According to LabMedica, “A wide array of metagenomic study efforts are hampered by the same challenge: low concentrations of targets of interest combined with overwhelming amounts of background signal. Although PCR or naive DNA capture can be used when there are a small number of organisms of interest, design challenges become untenable for large numbers of targets.”
Detecting Pathogens Faster, Cheaper, and More Accurately
As part of their study, researchers tested two probe sets:
one to target bacterial pathogens linked to sepsis, and
another to detect coronaviruses including SARS-CoV-2.
They were successful in using the probes to capture a variety of pathogens linked to sepsis and SARS-CoV-2.
“We validated HUBDesign by generating probe sets targeting the breadth of coronavirus diversity, as well as a suite of bacterial pathogens often underlying sepsis. In separate experiments demonstrating significant, simultaneous enrichment, we captured SARS-CoV-2 and HCoV-NL63 [Human coronavirus NL 63] in a human RNA background and seven bacterial strains in human blood. HUBDesign has broad applicability wherever there are multiple organisms of interest,” the researchers wrote in Cell Reports Methods.
The findings also have implications to the environment and wildlife, the researchers noted.
Of course, more research is needed to validate the tool’s usefulness in medical diagnostics. The McMaster University researchers intend to improve HUBDesign’s efficiency but note that probes cannot be designed for unknown targets.
Nevertheless, the advanced application of novel technologies to diagnose of sepsis, which causes 250,000 deaths in the US each year, according to the federal Centers for Disease Control and Prevention, is a positive development worth watching.
The McMaster scientists’ discoveries—confirmed by future research and clinical studies—could go a long way toward ending the dire effects of sepsis as well as COVID-19. That would be a welcome development, particularly for hospital-based laboratories.
Results of the UK study confirm for clinical laboratory professionals the importance of fully understanding the design and function of SNP chips they may be using in their labs
Here is another example of a long-established clinical laboratory test that—upon new evidence—turns out to be not as accurate as once thought. According to research conducted at the University of Exeter in Devon, UK, Single-nucleotide polymorphism (SNP) chips (aka, SNP microarrays)—technology commonly used in commercial genetic testing—is inadequate at detecting rare gene variants that can increase breast cancer risk.
A news release announcing the results of the large-scale study states, “A technology that is widely used by commercial genetic testing companies is ‘extremely unreliable’ in detecting very rare variants, meaning results suggesting individuals carry rare disease-causing genetic variants are usually wrong.”
Why is this a significant finding for clinical laboratories? Because medical laboratories performing genetic tests that use SNP chips should be aware that rare genetic variants—which are clinically relevant to a patient’s case—may not be detected and/or reported by the tests they are running.
UK Researchers Find ‘Shockingly High False Positives’
The conclusion reached by the Exeter researchers, the BMJ study states, is that “SNP chips are extremely unreliable for genotyping very rare pathogenic variants and should not be used to guide health decisions without validation.”
Leigh Jackson, PhD, Lecturer in Genomic Medicine at University of Exeter and co-author of the BMJ study, said in the news release, “The number of false positives on rare genetic variants produced by SNP chips was shockingly high. To be clear: a very rare, disease-causing variant detected using [an] SNP chip is more likely to be wrong than right.”
In the news release, Caroline Wright, PhD (above), Professor in Genomic Medicine at the University of Exeter Medical School and senior author of the BMJ study, said, “SNP chips are fantastic at detecting common genetic variants, yet we have to recognize that tests that perform well in one scenario are not necessarily applicable to others.” She added, “We’ve confirmed that SNP chips are extremely poor at detecting very rare disease-causing genetic variants, often giving false positive results that can have profound clinical impact. These false results had been used to schedule invasive medical procedures that were both unnecessary and unwarranted.” (Photo copyright: University of Exeter.)
Large-Scale Study Taps UK Biobank Data
The Exeter researchers were concerned about cases of unnecessary invasive medical procedures being scheduled by women after learning of rare genetic variations in BRCA1 (breast cancer type 1) and BRCA2 (breast cancer 2) tests.
“The inherent technical limitation of SNP chips for correctly detecting rare genetic variants is further exacerbated when the variants themselves are linked to very rare diseases. As with any diagnostic test, the positive predictive value for low prevalence conditions will necessarily be low in most individuals. For pathogenic BRCA variants in the UK Biobank, the SNP chips had an extremely low positive predictive value (1-17%) when compared with sequencing. Were these results to be fed back to individuals, the clinical implications would be profound. Women with a positive BRCA result face a lifetime of additional screening and potentially prophylactic surgery that is unwarranted in the case of a false positive result,” they wrote.
Using UK Biobank data from 49,908 participants (55% were female), the researchers compared next-generation sequencing (NGS) to SNP chip genotyping. They found that SNP chips—which test genetic variation at hundreds-of-thousands of specific locations across the genome—performed well when compared to NGS for common variants, such as those related to type 2 diabetes and ancestry assessment, the study noted.
“Because SNP chips are such a widely used and high-performing assay for common genetic variants, we were also surprised that the differing performance of SNP chips for detecting rare variants was not well appreciated in the wider research or medical communities. Luckily, we had recently received both SNP chip and genome-wide DNA sequencing data on 50,000 individuals through the UK Biobank—a population cohort of adult volunteers from across the UK. This large dataset allowed us to systematically investigate the performance of SNP chips across millions of genetic variants with a wide range of frequencies, down to those present in fewer than 1 in 50,000 individuals,” wrote Wright and Associate Professor of Bioinformatics and Human Genetics at Exeter, Michael Weedon, PhD, in a BMJ blog post.
The Exeter researchers also analyzed data from a small group of people in the Personal Genome Project who had both SNP genotyping and sequencing information available. They focused their analysis on rare pathogenic variants in BRCA1 and BRCA2 genes.
The researchers found:
The rarer the variant, the less reliable the test result. For example, for “very rare variants” in less than one in 100,000 people, 84% found by SNP chips were false positives.
Low positive predictive values of about 16% for very rare variants in the UK Biobank.
Nearly all (20 of 21) customers of commercial genetic testing had at least one false positive rare disease-causing variant incorrectly genotyped.
SNP chips detect common genetic variants “extremely well.”
Advantages and Capabilities of SNP Chips
Compared to next-gen genetic sequencing, SNP chips are less costly. The chips use “grids of hundreds of thousands of beads that react to specific gene variants by glowing in different colors,” New Scientist explained.
Common variants of BRCA1 and BRCA2 can be found using SNP chips with 99% accuracy, New Scientist reported based on study data.
However, when the task is to find thousands of rare variants in BRCA1 and BRCA2 genes, SNP chips do not fare so well.
“It is just not the right technology for the job when it comes to rare variants. They’re excellent for the common variants that are present in lots of people. But the rarer the variant is, the less likely they are to be able to correctly detect it,” Wright told CNN.
SNP chips can’t detect all variants because they struggle to cluster needed data, the Exeter researchers explained.
“SNP chips perform poorly for genotyping rare genetic variants owing to their reliance on data clustering. Clustering data from multiple individuals with similar genotypes works very well when variants are common,” the researchers wrote. “Clustering becomes more difficult as the number of people with a particular genotype decreases.”
Clinical laboratories Using SNP Chips
The researchers at Exeter unveiled important information that pathologists and medical laboratory professionals will want to understand and monitor. Cancer patients with rare genetic variants may not be diagnosed accurately because SNP chips were not designed to identify specific genetic variants. Those patients may need additional testing to validate diagnoses and prevent harm.
