Since all Americans have access to free COVID-19 vaccines, many pathologists and clinical lab managers will ask if this test is even necessary. Some experts say “maybe”
Here’s another example of genetic test developers who are willing to push boundaries and sell a diagnostic test directly to consumers that has some diagnostic experts and pathologists challenging its clinical validity.
The test was developed by molecular diagnostics company Genetic Technologies Ltd. (NASDAQ:GENE) of Melbourne, Australia, and, according to an article in Science, is an at-home saliva test that “combines genetic data with someone’s age, sex, and pre-existing medical conditions to predict their risk of becoming extremely ill from COVID-19.”
In a non-peer-reviewed preprint, titled, “Development and Validation of a Clinical and Genetic Model for Predicting Risk of Severe COVID-19,” Genetic Technologies’ Chief Scientific Officer Richard Allman, PhD, and Senior Biostatistician and the study’s first author, Gillian Dite, PhD, wrote, “Using SARS-CoV-2 positive participants from the UK Biobank, we developed and validated a clinical and genetic model to predict risk of severe COVID-19. … Accurate prediction of individual risk is possible and will be important in regions where vaccines are not widely available or where people refuse or are disqualified from vaccination, especially given uncertainty about the extent of infection transmission among vaccinated people and the emergence of SARS-CoV-2 variants of concern.”
But since every American already has access to free COVID-19 vaccines, one wonders why this test would be launched in the US?
Determining Risk for COVID-19 Infection
Can a genetic test predict an individual’s risk of contracting a SARS-CoV-2 infection that would require hospitalization or cause death? Genetic Technologies and its US partner, Infinity BiologiX (IBX) of Piscataway, N.J., believe so.
According to a Genetic Technologies news release, the saliva test, which reportedly costs $175, enables a “leading-edge risk assessment that estimates your personal risk of severe disease,” IBX says on its website.
The at-home saliva-based test, which is intended for people age 18 and older, gives a risk score for contracting a serious COVID-19 case based on genetic and clinical information, IBX stated in its own news release.
Is There a Place for Genetic COVID-19 Risk Test in the US?
“Alongside existing treatment options and vaccines, we believe this test will enable more insightful decisions for states, workplaces, and individuals,” said Simon Morriss, Genetic Technologies’ CEO, in the news release.
According to Science, “The test debuts in a regulatory gray zone …. The two companies did not seek [FDA] approval for validity because, [Genetic Technologies Chief Scientific Officer Richard Allman] says, the test is not a direct-to-consumer product that falls under its review. After a customer receives results from IBX’s federally-approved labs, they can consult with a ‘telehealth’ physician.”
“We are uniquely and strategically positioned with our partners to deliver the test and provide remote telehealth services and reporting, utilizing our extensive array capability and capacity across a number of platforms,” Grimwood said in the IBX news release.
However, Science reported that “Several geneticists who reviewed the company’s preprint” said “the test needs to be validated in other, more diverse populations than one detailed in the UK Biobank, and they wonder whether its predictions are reliable for people infected with new SARS-CoV-2 variants.”
The question remains unanswered as to why a genetic risk test for SARS-CoV-2 and its variants is needed in the United States. Nevertheless, clinical laboratory leaders and pathologists may want to monitor these developments for new biomarkers and COVID-19 diagnostics.
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.”
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.
With $191 million in startup capital, the genomics startup will draw on existing genetic databases to create personalized medicine therapies for chronic diseases
Why do some people get sick while others do not? That’s what genetic researchers at Maze Therapeutics want to find out. They have developed a new approach to using tools such as CRISPR gene editing to identify and manipulate proteins in genetic code that may be the key to providing personalized protection against specific diseases.
If viable, the results of Maze’s research could mean the development of specific drugs designed to mimic genetic code in a way that is uniquely therapeutic to specific patients. This also would create the need for clinical laboratories to sequence and analyze patients’ DNA to determine whether a patient would be a candidate for any new therapies that come from this line of research.
Based in San Francisco, Maze Therapeutics (Maze) is studying modifier genes—genes that affect the phenotype or physical properties of other genes—and attempting to create drugs that replicate them, reported MIT Technology Review. Maze believes that genetic modifiers could afford a “natural form of protection” against disease.
“If you have a disease-causing gene, and I have the disease-causing gene, why is it that you may be healthy and I may be sick? Are there other genes that come into play that provide a protective effect? Is there a drugging strategy to recover normal phenotype and recover from the illness?” Maze Chief Executive Officer Jason Coloma, PhD, asked in an interview with FierceBiotech.
In 2019, Maze received $191 million in financing from Third Rock Ventures, ARCH Venture Partners, and others, to find ways to translate their findings into personalized medicines, according to a news release. And with the availability of international public genetic databases and CRISPR gene editing, now may be good timing.
“This was the perfect time to get into this space with the tools that were being developed and the amount of data that has been accumulated on the human genetic side,” Charles Homcy, MD, Third Rock Ventures Partner and Maze Scientific Founder, told Forbes, which noted that Maze is tapping existing population-wide genetic databases and large-scale studies, including the United Kingdom’s Biobank and Finland’s Finngen.
To help find genetic modifier drug targets, Maze is accessing CRISPR gene editing capabilities. Jonathan Weissman, PhD, Maze Scientific Founder and Professor of Cellular Molecular Pharmacology at University of California, San Francisco (UCSF), told MIT Technology Review: “You take a cell with a disease-causing gene and then see if you can turn it back to normal. We can do 100,000 experiments at once because each cell is its own experiment.”
Using CRISPR to Identify the Cause of Disease
One drug research program reportedly progressing at Maze involves developing gene therapy for the neurogenerative disease amyotrophic lateral sclerosis (ALS). The program borrows from previous research conducted by Aaron Gitler, PhD, Professor of Genetics at Stanford University and Maze co-founder, which used CRISPR to find genetic modifiers of ALS. The scientists found that when they removed the protein coding gene TMX2 (Thioredoxin Related Transmembrane Protein 2), the toxicity of proteins building the disease was reduced, reported Chemical and Engineering News.
“We used the CRISPR-Cas9 system to perform genome-wide gene-knockout screens for suppressors and enhancers of C9ORF72 DPR toxicity in human cells,” Gitler and colleagues wrote in Nature Genetics. “Together, our results demonstrate the promise of using CRISPR-Cas9 screens in defining the mechanisms of neurodegenerative diseases.”
“We have the flexibility to think differently. We like to
think of ourselves as part of this new breed of biotech companies,” Coloma told
It’s an exciting time. Clinical laboratories can look
forward to new precision medicine diagnostic tests to detect disease and
monitor the effects of patient therapies. And the research initiatives by Maze
and other genetic companies represent a new approach in the use of genetic code
to create specific drug therapies targeted at specific diseases that work best
for specific patients.
The companion diagnostics that may come from this research would
be a boon to anatomic pathology.