Pharmacogenomics testing to optimize medical countermeasures against chemical warfare agents and bacterial biothreats in military settings

Abstract

Introduction:

Pharmacogenomics testing is a promising tool for strengthening medical countermeasures against military threats such as chemical warfare agents and bacterial biothreats. This review assesses the role of pharmacogenomics in military health care, highlighting distinct requirements in defence compared to civilian settings.

Methods:

We conducted a systematic review (PubMed, 2010-25) to identify publications focusing on pharmacogenomics, nerve agent susceptibility, and tularemia treatment. Key search terms included combinations relevant to genetic factors affecting chemical and bacterial threat responses. Studies were evaluated for genetic variations influencing nerve agent toxicity, related treatment responses, and antibiotic pharmacogenomics.

Results:

Genetic variants substantially impact susceptibility to nerve agents and the effectiveness of countermeasures. Polymorphisms in acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) modify toxicity risk and treatment response to oximes, atropine, and benzodiazepines. For bacterial biothreats, genetic factors affect antibiotic efficacy and risk for adverse reactions, especially with aminoglycosides, fluoroquinolones, and tetracyclines. Sex and gender differences in pharmacogenomic responses are important yet under-recognized.

Discussion:

Integrating pharmacogenomic testing in military health care has the potential to improve force protection and operational readiness for chemical and biological threats. Nonetheless, challenges remain, including cost, logistical feasibility in mass casualty events, and the development of rapid deployable testing platforms. Future research should emphasize validation studies and implementation strategies tailored for military needs.

Lay Summary

This review explains how genetic testing can help protect military personnel against chemical weapons and biothreats such as bacteria that causes tularemia. Individual genetic differences influence susceptibility to nerve agent and antibiotics, affecting both risk and treatment outcome. Using genetic data to guide health care could lead to more effective and personalized medical countermeasures in military settings. However, implementing these strategies in the military faces hurdles such as the costs of testing and the need for quick and practical solutions in emergencies.

Introduction

Military medicine requires innovative approaches to protect and treat personnel who face chemical and biological threats. Pharmacogenomics (PGx), the study of how genetic variations influence individual responses to drugs, represents a transformative tool to personalize military medical countermeasures based on individual genetic profiles.¹

Modern military medicine confronts unique challenges distinct from civilian health care applications. Service members may encounter chemical warfare agents (CWAs) such as nerve agents or face biological threats such as weaponized bacteria. Unlike civilian medicine, where detailed patient histories and diagnostics are often possible, military health care frequently requires immediate, life-saving care in austere settings with limited information. For example, a Canadian Armed Forces (CAF) member exposed to a nerve agent relies on immediate treatment, and their genetic makeup can influence both susceptibility to toxicity and response to therapy. Similarly, genetic factors may determine treatment efficacy against biothreat agents like Francisella tularensis (tularemia).

This review aims to achieve the following: 1) analyze how genetic variations influence individual responses to CWAs and associated therapies, particularly focusing on nerve agents and acetylcholinesterase (AChE) interactions, 2) evaluate the role of PGx in bacterial biothreat countermeasures, using tularemia as a representative model, and 3) explore practical implementation strategies for PGx in military settings considering unique operational constraints.

The potential of PGx in military medicine extends beyond individualized care; it also enhances force protection, efficient resource allocation, and mission success.¹ Recent military health systems studies show PGx testing can identify substantial numbers of personnel who might benefit from personalized medication regimens.² Sex and gender differences require attention in military PGx, as most research historically focuses on male populations. Understanding how genetic and physiological sex differences together shape drug responses remains essential for maximizing benefits for all service members.

By reviewing current research, identifying knowledge gaps, and proposing future priorities, this review provides a focus on PGx applications relevant to chemical and biological threat scenarios, with special attention to the complexities of combined drugs administration in military medicine.

Methods

This focused review synthesized current literature on PGx applications in military settings, specifically addressing CWAs and bacterial biothreats. Established systematic review methodologies were followed, adhering to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines to enhance transparency and reproducibility throughout the process.

Systematic searches were conducted in PubMed for publications dated from 2010 to 2025. Search terms included the following: “pharmacogenomics” AND “military,” “Acetylcholinesterase polymorphisms” AND “nerve agents,” “tularemia” OR “Francisella tularensis” AND “genetic factors” AND “antibiotics,” “pharmacogenomics” AND “chemical warfare,” “drug-drug-gene interactions” AND “military medicine,” “point-of-care” AND “military” AND “pharmacogenomics,” and “PanOmiQ.” All search results were exported, combined, and deduplicated according to PRISMA recommendations before being screened for relevance (Table 1). We first screened titles and abstracts for relevance to PGx applications and research in military contexts. Full-text articles were subsequently assessed for eligibility using predefined inclusion criteria: human studies or relevant animal models, focus on genetic variants affecting CWA or biothreat agent susceptibility/treatment, and emphasis on actionable PGx findings. Exclusion reasons at the full-text stage included lack of military or PGx focus, absence of biothreat or CWA data, case reports, or insufficient/irrelevant information.

Table 1.

Study selection and PRISMA flow summary

Step	Records
Records identified through PubMed searches	348
Duplicates removed	11
Records screened (titles/abstracts)	337
Full-text articles assessed for eligibility	41
Studies included in qualitative synthesis	8

From eligible studies, we systematically extracted the following information:

• Genetic variations in AChE and BChE genes and their impact on nerve agent toxicity and oxime reactivation efficiency

• Host genetic factors influencing antibiotic efficacy and toxicity in tularemia (e.g., MT-RNR1 for aminoglycoside ototoxicity, ABCB1 and OATP1A2 for fluoroquinolones and tetracyclines, UGT2B7 for chloramphenicol metabolism)

• Drug-drug-gene interactions relevant to combined administration of oximes, atropine, and benzodiazepines

• Sex and gender differences in PGx responses

Data synthesis prioritized actionable PGx results relevant for military health care implementation, giving special attention to sex and gender considerations, operational feasibility, cost-effectiveness factors, and the unique requirements of tactical medicine.

Results

Chemical warfare agents: nerve agent susceptibility and treatment

Nerve agents, such as Sarin, VX, and Novichok agents, represent the most lethal chemical warfare threats for military personnel. These compounds act by irreversibly inhibiting AChE at neuronal synapses, causing dangerous acetylcholine accumulation and overstimulation of the nervous system. Severe effects include convulsions, paralysis, and respiratory failure.³ AChE is the main molecular target of nerve agent toxicity, but butyrylcholinesterase (BChE) acts as a bio-scavenger, neutralizing some agents before they reach AChE.⁴

Genetic variations in cholinesterase enzymes

Genetic variations in both AChE and BChE meaningfully alter susceptibility to nerve agents and treatment outcomes.⁵ For example, the BChE gene contains multiple functional variants, notably the Ala567Thr (K-variant) produces 33% lower BChE activity,⁵ increasing the risk for toxicity after exposure. The AChE gene, meanwhile, is highly conserved, and severe deficiencies are almost never observed, reflecting its critical role in physiology. Individuals with BChE deficiency are at higher risk for nerve agent toxicity, as BChE normally shields AChE from inhibition. Screening for BChE variants may support pre-deployment risk assessment.

Treatment optimization

Standard treatment protocol for nerve agents includes an oxime (e.g., pralidoxime), atropine, and benzodiazepines (e.g., midazolam). Integrating PGx insights can improve both efficacy and safety of these regimens.¹ Oximes reactivate inhibited AChE, but genetic AChE variations may alter reactivation efficiency and enzyme complex stability.^5,6 For atropine, while specific PGx data are scarce, broader research on anticholinergics shows genetic polymorphisms can affect both efficacy and side effect risk.⁷

Benzodiazepine response is strongly influenced by PGx factors. Polymorphisms in GABA_A receptors, such as GABRA1 rs4263535, are associated with deeper sedation depth,⁸ while CYP3A5 variants affect pharmacokinetics of midazolam, possibly warranting dose adjustments, especially in urgent scenarios.⁹

Bacterial biothreat findings: tularemia as a model

F. tularensis is a Tier 1 select agent that is known for its high infectivity, potential use in bioterrorism, and requirement for immediate medical intervention. Multiple antibiotics, such as streptomycin, gentamicin, doxycycline, ciprofloxacin, and chloramphenicol, are approved for post-exposure therapy.¹⁰ However, treatment failures and relapses, particularly in immunocompromised or late diagnosed cases, underscore the value of a personalized approach.

PGx considerations for antibiotic therapy

PGx is increasingly recognized as critical for optimizing antibiotic treatment, such as in tularemia therapy. The mitochondrial DNA m.1555A>G mutation in MT-RNR1 elevates the risk of aminoglycoside-induced hearing loss, even at standard therapeutic doses.¹¹ Patients affected may require alternative antibiotics or enhanced monitoring. Other polymorphisms, such as ABCB1 (impacting ciprofloxacin) and OATP1A2 (influencing doxycycline), alter antibiotic absorption and metabolism, and they can thus lead to sub-therapeutic effects or adverse reactions.¹² UGT2B7 variants modify chloramphenicol glucuronidation, increasing toxicity risk in those with reduced metabolism.¹³

Host susceptibility factors

Host genetic factors can also influence susceptibility to F. tularensis infection and treatment outcomes. Toll-like receptor 4 (TLR4) polymorphisms may affect innate immune responses to F. tularensis lipopolysaccharide,¹⁵ potentially altering both disease severity and treatment response. Variants in the SLC11A1 gene have been associated with differential susceptibility to intra-cellular pathogens like F. tularensis in mouse models.¹⁴ Table 2 presents an overview of actionable PGx variants, the associated agents or drugs, and the resulting clinical implications.

Table 2.

Overview of actionable PGx variants, associated threats or drug, and treatment implications

PGx variant	Associated agent/drug	Treatment implication	Notes
AChE His353Asn5	Nerve agents	Normal AChE activity but may subtly alter oxime reactivation	Highly conserved; severe loss of function not observed
BChE Ala567Thr5	Nerve agents	33% reduced bio-scavenger activity; higher toxicity risk	Candidate for pre-deployment screening
GABRA1 rs42635358	Midazolam	Increased depth of sedation	Intronic; affects GABA_A receptor sensitivity
CYP3A5 1/3 alleles9	Midazolam	Alters clearance; may prolong sedation or adverse effects	Guides benzodiazepine dosing under acute exposure
MT-RNR1 m.1555A>G11	Aminoglycosides (streptomycin, gentamicin)	Strong risk factor for ototoxicity	Recommend alternative antibiotics or audiologic monitoring
ABCB1 (e.g., c.3435C>T)12	Fluoroquinolones (ciprofloxacin)	Modulates absorption/distribution; can decrease efficacy	May warrant dose adjustment
OATP1A2 variants12	Tetracyclines (doxycycline)	Affects uptake; potential sub-therapeutic levels	Important for rapid post-exposure prophylaxis
UGT2B7 polymorphisms13	Chloramphenicol	Reduced glucuronidation; increased toxicity risk	Narrow therapeutic window; PGx can guide safe dosing
SLC11A1 (NRAMP1) promoter variants14	F. tularensis	Influences intra-cellular killing; may affect antibiotic outcomes	Animal data support host-susceptibility role

PGx = pharmacogenomics; AChE = acetylcholinesterase; BChE = butyrylcholinesterase.

Implementation of PGx knowledge in military settings

Advanced genomic technologies for military applications

Military PGx implementation is rapidly advancing because of real-time genomic analysis platforms, such as PanOmiQ, which can deliver complete sequencing and clinical reports within seven hours.¹⁶ These innovations address the crucial need for rapid, actionable genetic information in operational environments, where delays are unacceptable. Deployable testing platforms enable point-of-care PGx in field or emergency scenarios that civilian systems cannot readily match.¹⁶

Military Health System implementation studies

Recent evidence from the Military Health System demonstrated the broad clinical utility of PGx screening. Targeted CYP2C19 and CYP2D6 genotyping has revealed a high prevalence of actionable variants among service members.^17,18 In one recent study, 81% participants had at least one abnormal result, and many were on medications influenced by these findings.¹⁷ Such data reinforce the ability of PGx-guided therapy to prevent adverse events and optimize medication selection within military populations.

Operational barriers and implementation challenges

Despite technological progress, field implementation contends with hurdles: rapid point-of-care testing capability, cost constraint, scalability for mass casualty events, and provider training.

Cost-effectiveness analyses demonstrate promise, but methods for resource allocation (who/when/how to test) remain unresolved.^19,20 Tiered approaches that prioritize high-risk PGx variants may offer pragmatic solutions, but pre-emptive comprehensive screening is preferred for maximal benefit.²¹

Provider preparedness is essential. Military health personnel need targeted education in PGx interpretation and must be equipped to make high-consequence decisions with limited genetic counselling time.²² Innovative approaches like telemedicine and remote consults can help close specialist gaps at geographically dispersed bases.²³

Sex and gender considerations for treatment optimization and safety

Sex and gender differences are a significant, yet understudied, consideration in military PGx. While most prior research has included predominantly male participants, growing gender diversity in the armed forces necessitates understanding both the biological and socio-cultural influences on drug response.^24-27 Women consistently show more frequent and severe adverse drug reactions,²⁵ underscoring the need for sex-stratified research and reporting. Sex-specific genetic differences in drug metabolism genes (e.g., higher male CYP1A2 protein/activity) directly translate to divergent therapeutic outcomes.²⁸ A concerted effort to include sex and gender sub-analyses, minimum reporting standards, and mainstreaming of these factors into all phases of military PGx research is required for equitable and effective implementation.

Discussion

The integration of PGx into military medical countermeasures is a substantial advance for both individual and collective force health.²⁹ This review demonstrates that genetic variations meaningfully affect susceptibility and treatment response for both CWAs and bacterial biothreats.

Military scenarios often require administration of multiple drugs under time pressure. These are circumstances in which drug-drug-gene interactions carry special risk. For example, polymorphisms in metabolic enzymes may unintentionally alter processing of one drug when multiple countermeasures are administered simultaneously.³⁰ This complexity becomes particularly relevant in nerve agent exposure, where combinational protocols (oximes, atropine, benzodiazepines) are the standard. Recent Military Health System studies support the clinical value of multi-gene PGx screening, with next-generation sequencing identifying actionable results in all participants compared to 81% with targeted genotyping.² These results suggest the need for broad, pre-emptive, and comprehensive genetic panels in military populations.

Implementation strategies and practical considerations

Integrating PGx into military medical countermeasures requires approaches that harmonize personalization benefits with operational realities. Evidence-based strategies include the following: conducting routine pre-emptive PGx screening of personnel, tailoring prophylactic and therapeutic regimens to individual genotypes, adjusting dosing and monitoring based on actionable variants, and strengthening real-world validation through field studies. Table 2 provides a summary of actionable PGx variants, their clinical significance, and operational impact. The CAF has begun studies examining prescriber attitudes and barriers to PGx, identifying logistics, cost, and training as key issues.^2,31 Evidence for utility is also emerging in psychiatric applications among CAF populations.³²

Addressing research gaps in sex- and gender-informed PGx in military medicine

Sex and gender issues should be explicitly integrated in future military PGx research. Drug dosing, adverse event monitoring, and deployment health strategies should be optimized to reflect the unique PGx and physiological profiles of all genders and ancestry groups. Efforts must include balanced gender representation, routine sex/gender sub-analyses of outcomes, adoption of reporting standards, and collaborations for data harmonization and equity.

Future research directions and limitations

Current PGx evidence is largely civilian derived and may lack generalizability to high-threat military field environments. Field conditions (stress, polypharmacy, and operational tempo), demand new research into gene-environment interactions. Priority should be given to rapid, deployable systems, large-field validation of key variants, and designing implementation protocols suited to mass-casualty and high-pressure settings.

Collaborative networks and international partnerships

Management of complex drug-drug-gene interactions necessitates collaboration, particularly within NATO and allied health research frameworks.^30,33 Collaborative research efforts and partnerships should include adverse drug reaction surveillance and antimicrobial resistance monitoring. Systematic sampling of real-time surveillance and integration with international clinical data-sharing platforms are necessary to advance PGx implementation and ensure future-proofed medical countermeasures guidance. The integration of PGx into military medical countermeasures remains both a major opportunity and a complex challenge. Evidence highlights strong health gains, but successful rollout will require ongoing research, sustained investment, and development of scalable solutions for provider preparation and resource allocation.

Biographies

Samuel Chekabab, PhD, is a research scientist at Defence Research and Development Canada’s Biological Threat Defence Section. His expertise includes host-pathogen interactions, antimicrobial resistance, and innovative biothreat detection technologies, contributing significantly to national defence science and international collaborations.

John Mikler, PhD, is a scientist at Defence Research and Development Canada’s Casualty Management Section. He contributes expertise in chemical weapon detection methods and biomedical countermeasures for national security applications, supporting Canadian defence research and innovation.

Funding Statement

No funding was received for this article.