BAP1 & Mesothelioma: How Simmons Hanly Conroy Confronts the BAP1 “Genetic Cause” Defense

The Rise of the Mesothelioma BAP1 Genetics Defense

Most mesothelioma claims resolve in an out-of-court settlement because companies are often confronted with clear evidence showing they knew about the dangers of asbestos and used it anyway. However, a growing number of defendants are willing to fight — and the weapon they’re reaching for is genetics.

At the center of this fight is a gene called BRCA1-associated protein 1, or BAP1. In a healthy body, the BAP1 gene helps suppress the growth of cancerous tumors. A person who inherits a mutation in that gene may have a weakened defense against several cancers, including mesothelioma.

Defendants are now arguing that a BAP1 mutation can cause mesothelioma on its own, entirely independent of asbestos exposure — even when that exposure is well documented. Our firm has become a national leader in confronting this defense.

When we take on a mesothelioma claim involving a BAP1 mutation, our team:

• Pinpoints the source of a client’s asbestos exposure by analyzing their work and family history
• Reframes the science for what it actually shows — that a genetic susceptibility means it took less asbestos to cause the disease, not that asbestos was irrelevant
• Neutralizes the genetics argument through pretrial motions that keep unsupported causation theories away from the jury
• Shares our proven work product with other plaintiff firms, so a victory in one courtroom strengthens the next

Companies have invested heavily in this defense, paying millions of dollars for papers to be published in favor of their claims and flying in expert witnesses from overseas to testify that a client’s cancer was written into their DNA at birth.

This strategy doesn’t need to prove the theory true — it only needs to make the science look uncertain enough that a jury pauses before potentially holding the company accountable.

Courts across the country have reached very different conclusions about the genetics defense. Some have kept it from the jury, while others have allowed it, making each ruling enormously consequential for future cases.

Learn how our mesothelioma law firm fought back against this approach in two recent cases.

1. A Landmark Louisiana Mesothelioma Victory Over a Genetics Defense

Our client was diagnosed with mesothelioma at just 39 years old. He carried a BAP1 gene mutation, which the defense attempted to argue was responsible for his illness.

By every measure, this was a devastating case. The father of two young sons and youth baseball coach was extraordinarily young for a disease that typically surfaces decades after exposure.

He was found to have two independently occurring mesotheliomas: pleural mesothelioma in the lining of his lungs and peritoneal mesothelioma in the lining of his abdomen. Over the course of his treatment, a third cancer was also discovered.

Despite the complexity of his diagnosis, our team was able to successfully uncover the source of his asbestos exposure and strike down the defense’s genetics argument.

Tracing a History of Secondary Asbestos Exposure

Our client didn’t work with asbestos during his career. Through careful investigation, we traced the exposure to his father, who worked for a general contractor performing construction at large petrochemical plants in New Orleans and Baton Rouge.

That work brought the man’s father into contact with older asbestos-containing gaskets and insulation. He unknowingly carried asbestos fibers home on his body and clothing from our client’s birth until he was roughly 9 years old.

These secondary or “take-home” exposure cases carry a particular grief. The father, who testified in the case, had unintentionally brought home the substance that would one day sicken his child. That burden is something our team is deeply sensitive to as we support families through the legal process.

The Presence of a BAP1 Mutation in a Mesothelioma Client

Throughout the case, it came to light that our client carried a BAP1 germline mutation, meaning the mutation was present in his body since birth. The mutation would become a central issue in his case.

The defense argued that our client’s BAP1 mutation, rather than asbestos exposure, was the cause of his mesothelioma. They retained a genetics expert from Italy to testify on their behalf. We filed a Daubert motion, which is intended to prevent unreliable science or unqualified experts from being introduced at trial.

The court granted it, ruling that the expert’s opinion was contrary to Louisiana law, which recognizes asbestos as the cause of mesothelioma.

The Win Now Being Used Nationwide

The defense’s paid-for genetics theory never reached the jury. The case ended in a confidential mesothelioma settlement that we understand may be one of the largest asbestos recoveries of its kind in Louisiana.

The last defendant to resolve the claim was the father’s employer. The case underscored the employer’s responsibility for asbestos exposure arising from the work the company assigned and the consequences that exposure could have for workers and their families.

The order to exclude the genetic expert’s testimony on BAP1 mutations is now being shared with other firms taking on mesothelioma lawsuits nationwide. It gives those firms a tool they can submit in support of their own motions to potentially keep the same genetics defense out of their trials.

2. Challenging a Family History of BAP1 Mutations & Mesothelioma

In Los Angeles, we have a client who is a research scientist and has authored more than 30 peer-reviewed journal articles. Her path to a mesothelioma diagnosis was unusual, beginning with a family history of cancer and health screenings.

After her older sister developed breast cancer and later mesothelioma, she and her younger sister underwent genetic testing and were found to carry both BAP1 and CHEK2 gene mutations.

Rather than allowing this case to center on genetics, our team instead focused on tracing the source of her asbestos exposure. By conducting an extensive investigation, we were able to prove how and where she encountered the mineral.

Confronting the BAP1 Causation Argument

After her diagnosis, our client decided to take legal action. Yet because of her BAP1 mutation, the defense claimed that her genetics, rather than asbestos exposure, caused the disease.

Our team challenged that argument and relied on the science: Having a BAP1 mutation can make a person more susceptible to cancer, but it doesn’t mean the mutation independently caused the mesothelioma.

Rather, a lower level of asbestos exposure may have been enough to cause her disease.

The Court ruled in our favor, preventing the defendant from claiming that our client’s BAP1 mutation was the cause of her and her sisters’ disease. Although the defendant was permitted to share that the client’s sisters passed away from mesothelioma, they could not suggest that the genetics caused their mesothelioma.

In fact, during trial, despite the defendant’s unsupported claims that our client’s sisters had no exposures, we were able to present evidence of asbestos exposures incurred by each of the client’s sisters.

This ruling allowed our mesothelioma attorneys and investigators to focus on tracing our client’s specific asbestos exposure, which was central to establishing how she developed the disease.

The Investigative Work Behind Tracing Asbestos Exposure

Instead of allowing the case to become a debate about genetics, we worked to prove where and how our client encountered asbestos. Our team pioneered an investigation into vermiculite-packaged laboratory products she was exposed to during her medical and chemistry training.

The vermiculite was mined at a W.R. Grace site in Libby, Montana, which was contaminated with asbestos. Unlike the chrysotile asbestos more commonly associated with laboratory equipment, vermiculite could expose workers to amphibole asbestos — a more potent form of the mineral commonly found in insulation.

No other firm had worked up this angle before. To prove exposure, we subpoenaed the W.R. Grace bankruptcy trust, recovering internal communications, safety documents, and records showing that the company conducted asbestos air-monitoring at a packaging facility and found levels exceeding OSHA limits.

The Question of Packaging Liability

To build our case, we located a former packaging-department employee who explained how the products were shipped. That raised a novel legal question: Can a manufacturer be held responsible for asbestos-containing packaging used to ship their products, even if another company made the packaging?

Our team argued that the manufacturer could be held accountable. In turn, their attorneys moved for summary judgment, asking the court to rule in their favor before a trial even began. The judge recognized the significance of the issue and ordered supplemental briefing before ruling.

Because California courts hadn’t squarely addressed the issue, our team built the argument by drawing on analogous product liability cases from outside asbestos litigation to show that manufacturers can be held responsible for what they ship, not just what they make.

Holding Companies Accountable, Not Genetics

The courts ruled in our favor, and we successfully established that a company shipping a hazardous package to a consumer can be held accountable.

This case demonstrates what it takes to confront today’s genetics defense. Rather than allowing the litigation to center on our client’s DNA, our team traced her asbestos exposure, developed evidence no other firm had previously pursued, and secured a favorable ruling on a novel legal issue.

Together, that work reinforced the central point of the case: A genetic mutation may make someone more vulnerable to asbestos, but it doesn’t erase a company’s responsibility for the exposure.

Ultimately, the case successfully settled after closing, during jury deliberations.

What These BAP1 Mesothelioma Cases Have in Common

Neither of these cases involved a straightforward exposure history. There was no U.S. Navy machinist’s mate pointing to an engine room or factory worker who could identify the asbestos-containing products he handled every day.

Even though our clients didn’t initially know how they had been exposed to asbestos, we were able to discover the answers through employment records, childhood histories, bankruptcy-trust archives, and corporate documents.

Three threads run through both BAP1 mesothelioma cases:

1. Genetics is now a central battleground: Whether a mutation is already in a client’s record or the defense is trying to compel testing, the “genetic cause” argument is a top issue in asbestos defense today. It raises serious ethical and privacy concerns, including what a forced genetic test could mean for a family’s future insurability. Our firm has been leading the charge in defeating it.
2. The science carries the case: When exposure histories are complicated, the science and evidence have to do the work. In these cases, our teams investigated nontraditional exposure sources, challenged the defense’s causation theories, and developed evidence to show what actually caused the disease.
3. Progress in one case can build something for other families: The genetics exclusion order from Louisiana and California is already being used by other firms in other states. The California packaging ruling, meanwhile, established a new path for holding companies accountable for asbestos exposure. Our work in these cases can become a tool to help families affected by a serious cancer get justice.

These cases show how our firm approaches the genetics defense. We investigate difficult exposure histories, challenge unsupported causation theories, and turn the lessons from each case into stronger strategies for the families who come next.

How Simmons Hanly Conroy Is Built for Complex Asbestos Claims

Our firm is structured in a way few others are — around dedicated trial teams. That structure gives clients access to the resources, document library, and national reach of one of the country’s largest mesothelioma law firms while preserving the personal experience of working with a small, consistent group of attorneys who know their case intimately and remain directly accessible.

Likewise, our talc department focuses on tracing exposure to specific products and mines, while our dedicated bankruptcy team handles asbestos trust fund claims.

Our trial teams meet regularly to compare notes on shared defendants, so a strategy that works in one jurisdiction travels to the next. With more documents on these defendants than any other firm, every new claim starts with decades of evidence and prior case experience behind it.

Confronting the BAP1 defense takes more than a good cross-examination — it takes a firm that understands the science behind mesothelioma well enough to spot when it’s being misused.

Confronting the BAP1 Defense & Standing at the Cutting Edge of Asbestos Litigation

The BAP1 genetics defense represents one of the most significant shifts in asbestos litigation in years. Defendants are spending millions trying to convince juries that a family’s tragedy was written into their genes.

Meeting that argument requires a firm that understands the science deeply enough to challenge it, has the courtroom experience to keep unsupported theories away from a jury, and is willing to do the painstaking investigative work these cases demand.

For more than 25 years, Simmons Hanly Conroy has focused extensively on asbestos and mesothelioma litigation, building the experience, resources, and knowledge needed to take on increasingly complex cases.

To date, we’ve secured over $10.6 billion in mesothelioma compensation for thousands of families nationwide.

If you or a loved one has been diagnosed with mesothelioma, call (800) 326-8900 now or fill out our contact form to learn how our team may be able to help.