Be part of the knowledge.

We’re glad to see you’re enjoying ReachMD…
but how about a more personalized experience?

Register for free

Leading MS/PML Experts Recommend Genetic Testing to Prevent Fatal Brain Infection

ReachMD Healthcare Image

In an editorial in the journal Frontiers in Neurology, two leading multiple sclerosis (MS) experts are advocating for genetic testing to identify MS patients who are at higher risk of developing a devastating side effect from their medications. 

People with MS are faced with the excruciating decision of whether they should take medications that are effective in slowing the progression of the disease, but may also trigger this potentially fatal complication, a rare brain infection called progressive multifocal leukoencephalopathy (PML).

The two authorities, Joseph Berger, MD, and Hans-Peter Hartung, MD, write, “The availability of a simple, relatively inexpensive test that can identify the genes that put one at risk for PML would be enormously helpful in the management of patients. The widespread use of such testing could potentially allow the physician to use alternative therapies that do not carry the same risk of PML.”

Dr. Berger is MS Division Chief at the University of Pennsylvania Perelman School of Medicine and Dr. Hartung is Neurology Chair of Heinrich Heine University in Düsseldorf, Germany and a Specialty Chief Editor for Frontiers in Neurology.

The editorial was written in support of a recently published study that confirmed a strong link between four genetic mutations and PML. The original study, also published in Frontiers in Neurology, found that these four variants were far more common among patients who took PML-linked drugs and developed PML than patients who took those drugs and did not develop PML. Neither of the editorial authors were affiliated with the original study. 

PML Patient and Tysabri Inventor Support Genetic Testing

"Preventative screening for these variants should become part of the standard of care,” said Dr. Lawrence Steinman, whose lab developed Tysabri, a breakthrough MS treatment that carries a Black Box Warning for PML. And when Franklin Jordan, 58, a PML survivor who developed the side-effect after taking Tysabri, learned about the availability of the genetic test, he said, “I would have taken the test in a minute. If I knew I was positive, I wouldn’t have taken Tysabri.” 

It is expected that preventative screening will become a routine part of patient care, as recommended by Drs. Berger, Hartung, and Steinman. But to fill the immediate need, the PML Foundation is currently offering a free test online. Simpler than a COVID swab, the at-home saliva test is processed in a CLIA-certified lab by PreventionGenetics, a leader in the field for almost 20 years. The free test is available at    

PML is caused by the JC virus, which is very common but remains dormant in the vast majority of carriers. However, certain immune-modifying drugs, including those used to treat MS, have been found to induce PML in rare cases.

Many MS medications currently carry a PML warning, including Tysabri, Ocrevus, and Rituxan, as well as Gilenya, Kesimpta, Mavenclad, Mayzent, Ponvory, and Tecfidera. But it’s not just MS drugs that can lead to PML; medications widely prescribed for blood cancers and organ transplants, as well as autoimmune diseases like inflammatory bowel disease, lupus, and rheumatoid arthritis also include PML warnings on their drug labels.

Drug-induced PML is on the rise as more powerful immunosuppressant therapies are developed. Since 2011, drug-induced PML cases reported to the FDA have more than doubled. And in 2022 alone, there were nearly 600 cases in the FDA’s adverse event reporting system. In that database, over 70 drugs have been linked to PML. 

Link to editorial:

The original study was funded by Emerald Lake Safety LLC and Population Bio Inc.

About Emerald Lake Safety

Emerald Lake Safety (ELS) conducts research into the mechanisms behind Serious Adverse Events associated with marketed pharmaceuticals. We conduct clinical and genomic research both on our own and in conjunction with leading academics and scientists from around the world. For more information visit

About Population Bio

Population Bio is a precision medicine company with a mission to make pharmaceuticals safer and more effective. By discovering disease-relevant genetic biomarkers, Population Bio helps develop targeted therapies and companion diagnostics faster and more cost effectively. Population Bio’s patented technology platform is currently addressing complex neurological diseases such as Alzheimer’s, Parkinson’s, and Autism, as well as women’s health conditions such as Endometriosis. For more information, visit

Press Contact:

Amy Losak


Frontiers in Neurology

Method of Research


Subject of Research


Article Title

Commentary: Progressive multifocal leukoencephalopathy genetic risk variants for pharmacovigilance of immunosuppressant therapies

Article Publication Date


Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.

Facebook Comments

Schedule17 Jun 2024