Blogs from April, 2026

BAP1, Genetic Testing, and the Evolving Battle Over Defense Expert Testimony in Mesothelioma Litigation

In recent years, defendants in mesothelioma litigation have increasingly attempted to shift attention away from decades of occupational asbestos exposure by emphasizing genetic explanations for disease. One of the most commonly referenced subjects in this effort is the BAP1 mutation — a genetic alteration that has become a recurring topic in defense medical testimony.

While legitimate scientific inquiry into genetics is important, plaintiff attorneys should recognize a troubling trend: some defense experts attempt to weaponize complex genetic concepts in ways that overstate uncertainty and minimize the devastating role asbestos exposure played in causing mesothelioma.

What is BAP1?

BAP1 (BRCA1-associated protein 1) is a tumor suppressor gene. Certain inherited mutations in BAP1 have been associated with increased susceptibility to several cancers, including mesothelioma, uveal melanoma, renal cell carcinoma, and others.

Importantly, however, the existence of a BAP1 mutation does not “cause away” asbestos exposure.

In fact, much of the scientific literature suggests the opposite: individuals with BAP1 mutations may actually be more susceptible to the carcinogenic effects of asbestos exposure. In other words, asbestos remains the environmental trigger, while the mutation may simply increase vulnerability.

This distinction is critical — and often blurred by defense experts attempting to create confusion before juries.

The Emerging Defense Strategy

Defense experts increasingly attempt to present genetic susceptibility as an alternative explanation for mesothelioma, subtly reframing the disease as primarily hereditary rather than exposure-driven. In some cases, juries are presented with highly technical testimony designed less to educate than to obscure.

This strategy can be particularly misleading when:

• The plaintiff had substantial occupational asbestos exposure;
• The expert minimizes cumulative exposure science;
• The expert ignores decades of epidemiological evidence linking asbestos to mesothelioma;
• Or the defense suggests that the mere possibility of a genetic predisposition somehow negates causation.

That is not how causation works in toxic tort litigation.

A genetic predisposition does not immunize asbestos manufacturers, premises owners, or contractors from responsibility when dangerous exposures substantially contributed to disease development.

The Danger of “Speculative Genetics”

Mesothelioma remains one of the clearest signature diseases associated with asbestos exposure in modern medicine. Yet some defense experts now attempt to leverage evolving genetic science to manufacture uncertainty where little truly exists.

Too often, these opinions rely on:

• speculative assumptions,
• incomplete genetic data,
• selective literature citation,
• or misleading implications unsupported by the patient’s actual medical history.

Even more concerning, some experts imply that if a genetic marker exists, occupational exposure becomes somehow less important. Scientifically and legally, that proposition is deeply flawed.

A worker with increased susceptibility does not become less injured because the hazard was more dangerous to them.

Plaintiff Attorneys Must Be Prepared

As defense firms continue investing heavily in sophisticated medical causation defenses, plaintiff attorneys must be equally prepared to challenge overreaching expert testimony grounded in distorted presentations of genetics.

That includes:

• understanding the evolving BAP1 literature,
• retaining qualified medical and genetic experts,
• exposing speculative opinions during cross-examination,
• and emphasizing that susceptibility is not synonymous with sole causation.

Jurors deserve clarity, not confusion disguised as science.

The Reality Defendants Cannot Escape

For decades, industrial companies, manufacturers, and employers exposed workers to asbestos-containing products while the hazards became increasingly understood throughout the scientific and corporate communities.

Now, as verdicts in mesothelioma litigation continue to command significant values, some defense experts appear increasingly willing to search for alternative narratives untethered from the realities of occupational exposure.

Genetics may influence susceptibility. But susceptibility is not absolution.