Conditions such as depression, anxiety, post-traumatic stress disorder (PTSD), and attention-deficit/hyperactivity disorder (ADHD) affect millions worldwide.

In recent years, genomic analysis has emerged as a powerful tool for understanding mental health. By examining genetic variations, epigenetic changes, and gene–environment interactions, researchers are uncovering how biology contributes to vulnerability, resilience, and treatment response.

The key to good genomics research is good sample collection. Non-invasive DNA collection methods, such as saliva and buccal swabs, make it possible to collect samples from a wide range of subjects, and integrate large-scale genomic data with psychological and clinical measures.

Isohelix sample collection, stabilization and extraction products have been adopted worldwide because of their ease of use, high-quality DNA yield, and suitability for large-scale studies. In this blog, we showcase how Isohelix technology is supporting breakthrough findings across four recent studies in psychiatry, genetics, and child development.

Read on to see how these interesting studies used Isohelix products to collect and process DNA samples that were used for a range of different analyses including microarray genotyping, next generation sequencing, methylation analysis, and PCR.

1. “The role of environmental sensitivity in the mental health of Syrian refugee children: a multi-level analysis.”

May, Andrew K., et al. “ Molecular Psychiatry (2024): 1-10. 

For this study, saliva samples were collected using Isohelix GeneFix kits from over 1,500 Syrian refugee children, and DNA was extracted and genotyped using the Illumina Infinium Global Screening Array. After stringent QC and imputation, researchers generated polygenic scores (PGS) for neuroticism, environmental sensitivity, and related traits.

The key findings were that self-reported sensitivity predicted higher risks of depression, anxiety, PTSD, and externalizing behaviors. However, genetic and hormonal markers, did not consistently predict outcomes. The study concluded saliva-based genetic analysis is feasible and robust, but that the clinical utility for predicting sensitivity in high-risk children remains limited.

2. “Impact of CYP2C19 metaboliser status on SSRI response: a retrospective study of 9500 participants of the Australian Genetics of Depression Study.”

Campos, Adrian I., et al.  The Pharmacogenomics Journal 22.2 (2022): 130-135

The results suggested that pharmacogenomic studies should focus on increasing sample sizes and implementing interventional or longitudinal studies sufficiently powered to assess whether metaboliser status is not only statistically but also clinically relevant to treatment with SSRIs.

3. “Posttraumatic stress disorder, adverse childhood events, and buccal cell telomere length in elderly swiss former indentured child laborers.”

Küffer, Andreas Lorenz, et al. Frontiers in Psychiatry 7 (2016). 

In this study, the role of childhood trauma was assessed as a potential additional risk factor for shorter telomere length.

Buccal cell samples collected from elderly Swiss participants using Isohelix Buccal Swabs. Collected cells were stored with DNA stabilizer until further preparation. The insertion of a Dri-Capsule (Cell Projects, Kent, UK) allowed the sample to be stored at room temperature without DNA degeneration and then DNA was extracted and analysed to measure telomere length by quantitative PCR (qPCR), which is a marker of cellular aging

Contrary to expectations, PTSD and childhood trauma were not associated with shorter telomeres in late life. Surprisingly, individuals with PTSD showed a trend toward longer telomere length. This highlights the complexity of linking early-life trauma, psychiatric disorders, and biological aging, and the value of buccal swabs for large-scale, low-burden sampling in older populations.

4. “Methylation Dynamics on 5′-UTR of DAT1 Gene as a Bio-Marker to Recognize Therapy Success in ADHD Children.“

Carpentieri, V. et al., Children 2023, 10, 584.)

Interestingly, children who improved after therapy showed distinct methylation patterns at specific CpG sites compared to those who remained severe. These epigenetic signatures may serve as objective biomarkers of treatment success, supporting personalized medicine in ADHD care. The study highlighted the importance of non-invasive buccal DNA collection for monitoring molecular changes in pediatric patients.

Conclusion

Isohelix DNA collection and stabilization kits provided the foundation for reliable, non-invasive, and scalable genetic and epigenetic analysis across these diverse studies. From polygenic risk scoring to pharmacogenomics and biomarker discovery, Isohelix products enabled researchers to unlock insights that bring us closer to precision psychiatry and personalized medicine.

To find out how Isohelix can help with DNA sample collection and isolation for your study, visit www.isohelix.com.

Isohelix Swabs can be used for human or animal donors

Isohelix Buccal Swabs make DNA sampling easy, whether the donor is human or an animal! In this recent study by Dutra et al (2024), the donors were canine, and the study was to evaluate the potential of using dogs’ apparent age, judged from photographs, as a non-invasive tool for assessing their welfare.

Relative Telomore Length

Can apparent age be used as an indicator of welfare?

Traditional welfare assessment methods often rely on behavioral and physiological indicators, which can be resource-intensive and invasive. This research explored whether apparent age, a measure used in humans to predict health and longevity, can also serve as an indicator of welfare in dogs by investigating its association with RTL.

Contact us to find out more about how Isohelix products can help with your sample collection, preservation and isolation.

Read the full paper here: https://www.mdpi.com/2813-9372/1/3/26

As DNA testing becomes more accessible and cost-effective, its applications in research, healthcare, and direct-to-consumer services, such as microbiome and ancestry testing, continue to expand. At Isohelix, we’re proud to support this growth by providing high-quality DNA collection and stabilization solutions. Whether you’re studying rare inherited disorders, using genomics to tailor drug treatments for patients, or helping consumers explore their ancestral roots, the success of your genetic analysis starts with reliable sample collection.

In this article, we examine key application areas where DNA collection plays a pivotal role, ranging from lifestyle genomics to cancer diagnostics. Read on to learn more about:

• Unlocking Complex Traits with GWAS
• Calculating Genetic Health Risks
• Pharmacogenetics and Pharmacogenomics
• Carrier Screening for Inherited Disorders
• Lifestyle genomics
• Microbiomics

Unlocking Complex Traits with GWAS

What is GWAS used for?

Genome-wide association studies (GWAS) compare genetic differences between samples from donors with and without a disease or trait, to find links. The primary genetic variations researchers look for are single nucleotide polymorphisms (SNPs), which represent a difference in a single nucleotide and are the most common type of genetic variation. SNPs commonly occur between genes, where they can be used as biological markers to help scientists locate genes associated with a disease or trait, within a gene, or in a regulatory region near a gene where they may affect the gene function and play a direct role in the trait or disease.

Multi-center GWAS projects often collect DNA from large numbers of individuals, utilizing high-throughput genotyping platforms, such as SNP arrays, to identify associations between SNPs and traits. These studies extract DNA from large cohorts, often over a wide geographical area, that must be collected and preserved to ensure consistent quality across the study.

Historically, DNA was collected from blood for GWAS studies, but as DNA collection and stabilization technology have improved for saliva and buccal swabs, these sample types are now commonly used.  Saliva collection is a safe and non-invasive process, and saliva collection kits can be mailed to donors for self-collection at home. Read more about how Isohelix saliva collection kits are replacing blood sampling at https://isohelix.com/saliva-instead-of-blood/.

Calculating Genetic Health Risks

For example, Polygenic Risk Scores (PRS) have been widely used in breast cancer research to stratify risk and inform screening and prevention strategies. Integrating PRS into clinical practice enables healthcare providers to deliver more accurate risk assessments, personalized prevention strategies, and optimized screening programs.

Pharmacogenetics and Pharmacogenomics

What’s the difference between pharmacogenetics and pharmacogenomics? Although the terms are often used interchangeably, pharmacogenetics is a subset of pharmacogenomics, which focuses on understanding how genetic variations influence an individual’s drug response. By contrast, pharmacogenomics refers to the investigation of the collective influence of the entire genome on a drug response.

Pharmacogenetic/genomic testing is revolutionizing precision medicine by helping clinicians prescribe drugs that are more likely to be effective for patients and less likely to cause side effects based on the patient’s genetic makeup.

Knowing a patient’s genotype at a specific locus can help doctors select the correct medication and dosage. For example, variants in the CYP2C19 gene affect how a patient metabolizes clopidogrel, a commonly prescribed blood thinner[i].

Pharmacogenetic/genomic testing is revolutionizing precision medicine by helping clinicians prescribe drugs that are more likely to be effective for patients. and less likely to cause side effects based on the patient’s genetic makeup.

Real-time PCR (qPCR) is often used in pharmacogenetics, where a fast turnaround time is necessary, and a single or small number of genes are being investigated. For pharmacogenomics, whole genome SNP arrays provide genotype information on hundreds of thousands of loci. Blood and/or saliva samples can be used to generate genotyping data with both technologies.

Carrier Screening for Inherited Disorders

Lifestyle genomics

Microbiomics

Many testing providers pair results with personalized diet or supplement recommendations based on the individual’s microbial profile. The accuracy of microbiome insights relies on high-quality, well-preserved samples, making robust DNA collection and stabilization methods essential to ensure reliable sequencing data.

Isohelix DNA Collection and Stabilization

 At Isohelix, we understand the importance of high quality DNA collection, extraction and preservation.  Our GeneFix^TM collection features high-yielding sample collectors that seamlessly integrate with our expanding range of Isohelix DNA collection, extraction and stabilization kits. These genetic sampling kits are specifically designed to provide exceptional DNA purity and yield, whether for life science research, molecular diagnostics, or forensic applications.

Visit our website to find out more: https://isohelix.com/

[i] Brown SA, Pereira N. Pharmacogenomic Impact of CYP2C19 Variation on Clopidogrel Therapy in Precision Cardiovascular Medicine. J Pers Med. 2018 Jan 30;8(1):8. doi: 10.3390/jpm8010008. PMID: 29385765; PMCID: PMC5872082.

[ii] Zakaria NH, Hashad D, Saied MH, Hegazy N, Elkayal A, Tayae E. Genetic mutations in HER2-positive breast cancer: possible association with response to trastuzumab therapy. Hum Genomics. 2023 May 18;17(1):43. doi: 10.1186/s40246-023-00493-5. PMID: 37202799; PMCID: PMC10193616.

Further Reading

• Genome Wide Association Studies (GWAS)

Milona, M., et al. Association of Three Genetic Loci with Molar Incisor Hypomineralization in Polish Children. J. Clin. Med. 2024, 13, 857. https://doi.org/10.3390/jcm13030857

• Genetic health risks

Mitchell, Brittany L., et al. “Polygenic risk scores derived from varying definitions of depression and risk of depression.” JAMA psychiatry 78.10 (2021): 1152-1160. https://doi.org/10.1001/jamapsychiatry.2021.1988

• Pharmacogenetics

Lind, Penelope A., et al. “Clozapine efficacy and adverse drug reactions among a nationwide study of 1021 Australians prescribed clozapine: The ClozaGene Study.” Schizophrenia Bulletin (2024): sbae065. https://doi.org/10.1093/schbul/sbae065

• Carrier screening

Rajan-Babu, Indhu-Shree, et al. “Defining the performance parameters of a rapid screening tool for FMR1 CGG-repeat expansions based on direct triplet-primed PCR and melt curve analysis.” The Journal of Molecular Diagnostics 18.5 (2016): 719-730. https://doi.org/10.1016/j.jmoldx.2016.05.002

• Lifestyle Genomics

Kazan, H.H., Bulgay, C., Zorba, E. et al. Exploring the relationship between caffeine metabolism-related CYP1A2 rs762551 polymorphism and team sport athlete status and training adaptations. Mol Biol Rep 51, 841 (2024). https://doi.org/10.1007/s11033-024-09800-2

• Microbiomics

Saifon, W., Sensorn, I., Trachu, N. et al. Gastrointestinal microbiota profile and clinical correlations in advanced EGFR-WT and EGFR-mutant non-small cell lung cancer. BMC Cancer 22, 963 (2022). https://doi.org/10.1186/s12885-022-10050-3

A study in Clinical Epigenetics by Willems et al (2024), examined whether self-control is associated with buccal and saliva DNA-methylation (DNAm) measures of biological aging, and whether biological aging measured in buccal DNAm is associated with self-reported health status.

The study found that in older participants (57–72 years), lower self-control was associated with more advanced biological aging, but this was not the case in young adults, adolescents or children. These associations were present even after correcting for possible confounders such as socioeconomic contexts, BMI, or genetic correlates of low self-control. The results also indicated that both advanced biological age and a faster pace of aging as measured by buccal DNAm, were associated with more self-reported disease.

The findings are consistent with the hypothesis that self-control is associated with health via pathways that accelerate biological aging in midlife and older age. 

Click here to see other publications that used Isohelix products to investigate methylation status: https://isohelix.com/publications/

Read the open-access paper here: https://doi.org/10.1186/s13148-024-01637-7

Introduction

Blood samples have traditionally been considered the gold standard DNA source for genomic analysis, but obtaining blood samples is a painful, invasive, and costly procedure that must be performed by qualified personnel.

By contrast, saliva collection is safe and non-invasive, and saliva collection kits can be mailed to donors for self-collection at home. Over the past two decades, saliva-based DNA collection has become routine for population-scale genetic studies, clinical research, and emerging diagnostic applications.

This article outlines how saliva is currently used for genetic studies, discusses technical considerations for sample processing and analysis, and explores future opportunities and challenges for this evolving field.

• Why use saliva as a source of genomic DNA?
• Genetic Analysis Techniques Used For Saliva-Based Studies
• The Challenges of Using Saliva DNA
• Genetic Research Using Saliva: Emerging Directions and Future Opportunities
• Conclusion
• GeneFix DNA/RNA Products

Why use saliva as a source of genomic DNA?

“Saliva is much easier and cheaper to collect and transport than blood.”

Saliva contains a mixture of buccal epithelial cells and leukocytes, from which high-quality genomic DNA can be extracted. In a study comparing DNA extracted from saliva and blood, Looi et al [i] (2012), the DNA yield from saliva of 7.8 µg/0.5 mL from a manual purification method was comparable to the DNA yield from blood using a salt precipitation method (7.4 µg/0.5 mL blood sample). DNA extracted from saliva and blood were both high purity (A260/280 > 1.70).

Genetic Analysis Techniques Used For Saliva-Based Studies

The range of genetic analysis tools used for saliva-based studies has expanded over the years. The key techniques are outlined below:

1. Single Nucleotide Polymorphism (SNP) Genotyping Arrays

2. Next Generation Sequencing (NGS) Using Saliva Samples

NGS can provide data on thousands of genes at once from multiple samples, enabling the discovery and analysis of a wide variety of genome features. In general, NGS requires lower amounts of input DNA than microarrays, but the data analysis can be complex and costly. As costs come down and data analysis tools become more sophisticated, NGS is increasingly being used in clinical genetics, particularly for Mendelian disease diagnosis and pharmacogenomics.

NGS can be used to look at the whole genome or specific sections of interest. There are three main types of NGS:

Whole Genome Sequencing: As the name suggests, in Whole Genome Sequencing (WGS) the whole genome is sequenced, including non-coding regions, structural variants, and mitochondrial DNA. WGS is being adopted for research biobanks and clinical diagnostics as costs decline to extract as much data from samples as possible.

Targeted NGS: In Targeted NGS, samples are enriched for the areas of interest using hybridization capture or amplicon sequencing, and then only these areas are sequenced. Hybridization capture uses biotinylated oligonucleotide probes to capture the regions of interest, while amplification uses PCR. Targeted sequencing is faster and more cost-effective than WGS, allowing for deeper sequencing of areas of interest. Targeted sequencing is an especially sensitive and powerful method for identifying variants and mutations, including rare variants.  

Whole Exome Sequencing (WES): Only the protein-coding regions (~1–2% of the genome) are sequenced in WES, often including rare or clinically significant variants. Traditionally whole exome sequencing was performed instead of WGS, to keep costs down.

3. Mitochondrial DNA Analysis

The mitochondrial genome mutates much faster than the nuclear genome, making mitochondrial DNA a valuable tool for systematics, evolutionary biology research, population genetics, and conservation biology research.

Mitochondrial DNA (mtDNA) can also be used for genetic epidemiological studies, and forensics.

4. PCR

5. DNA Methylation Studies

In 2019, Murata et al[iv], found that in addition to high correlation in DNA methylation profiles, CpG sites showing large interindividual DNA methylation differences were similar between blood and saliva, so saliva could be an alternative source of genomic DNA for cohort studies, as long as source‐dependent DNA methylation differences were considered.

The Challenges of Using Saliva DNA

• Variable DNA Quality: Degradation due to improper storage or low epithelial cell content can affect downstream applications, especially WES and WGS. DNA integrity is crucial for detecting structural variants or phasing haplotypes.
• Microbial Contamination: Co-extraction of bacterial DNA can reduce sequencing efficiency. Metagenomic filtering and human-specific capture protocols help mitigate this, though they increase cost and complexity.
• Sample Identity and Mix-ups: Self-collection increases the risk of sample mix-up or contamination. Barcoding, digital tracking, and sample fingerprinting via SNP profiles are used to verify identity and minimize these issues.

Genetic Research Using Saliva: Emerging Directions and Future Opportunities

1. Liquid Biopsy Applications

Saliva is being explored as a non-invasive liquid biopsy medium, particularly for cancers localized to the oral cavity, pharynx, or lungs. ctDNA and exosomes can be isolated from saliva and analyzed via droplet digital PCR (ddPCR), targeted sequencing, or methylation assays. While sensitivity remains lower than plasma-based liquid biopsies, saliva offers a complementary diagnostic approach.

2. Pharmacogenomics and Precision Medicine

Clinical-grade saliva tests are being developed to guide therapeutic decisions based on variants in genes such as CYP2D6, SLCO1B1, and DPYD. Saliva-based assays offer a valuable route for predictive testing in primary care, psychiatry, and oncology.

3. Decentralized Clinical Trials and Global Health

Saliva-based genotyping supports remote enrolment and sample collection in decentralized clinical trials. This is especially valuable in rare disease research and studies requiring diverse representation. With minimal infrastructure needs, saliva testing can enhance genetic screening in low- and middle-income countries.

4. Genetic Epidemiology and Behavioural Studies

Saliva-based DNA collection has facilitated the expansion of socio-genomic research, including studies on educational attainment, cognitive function, and mental health disorders. Twin studies and family-based designs increasingly rely on at-home kits for sample collection, improving retention and longitudinal follow-up.

5. AI and Predictive Modelling

The growing volume of genotypic and phenotypic data from saliva-based studies is well suited to machine learning approaches. AI models are being used to improve variant interpretation, identify complex trait associations, and predict treatment outcomes from polygenic and environmental features.

6. Multi-omic Profiling

Saliva contains not only DNA but also RNA, proteins, metabolites, and microbial communities. Recent studies have demonstrated the feasibility of salivary transcriptomics, proteomics, and microbiome sequencing, paving the way for integrated multi-omic analyses.

These data types could enable early disease detection, especially in inflammatory, metabolic, or neurodegenerative conditions. For example, salivary miRNAs and extracellular vesicles are being investigated as biomarkers for Alzheimer’s and head & neck cancers.

Conclusion

Saliva has emerged as a practical, scalable biospecimen for genomic research and clinical applications. It enables high-throughput sample collection, democratizes access to genetic testing, and supports multi-omic innovation. While challenges in sample quality, microbial contamination, and data interpretation persist, ongoing technical advances are steadily improving the reliability and breadth of saliva-based assays.

As we move toward a more personalized, preventative healthcare model, saliva will likely serve as a cornerstone of population genomics and precision medicine—offering a low-friction path from collection to insight.

GeneFix DNA/RNA Products

DOWNLOAD OUR BROCHURE HERE

Related Blogs:

• To read more about using saliva instead of blood for genetic testing, click here: https://isohelix.com/saliva-instead-of-blood/
• For a discussion of the DNA extraction methods for saliva click here: https://isohelix.com/the-best-dna-extraction-methods-from-saliva-or-buccal-swabs/

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[i] Looi ML, Zakaria H, Osman J, Jamal R. Quantity and quality assessment of DNA extracted from saliva and blood. Clin Lab. 2012;58(3-4):307-12. PMID: 22582505

[ii] Ng DP, Koh D, Choo S, Chia KS. Saliva as a viable alternative source of human genomic DNA in genetic epidemiology. Clin Chim Acta. 2006 May;367(1-2):81-5. doi: 10.1016/j.cca.2005.11.024. Epub 2006 Jan 4. PMID: 16388788.

[iii] Ganie, M. W., Nainggolan, I. R. A., Bestari, R., Hazidar, A. H., Hasibuan, M., Siregar, J., Ichwan, M., Kusumawati, R. L., & Lubis, I. N. D. (2023). Use of saliva as an alternative diagnostic method for diagnosis of COVID-19. IJID Regions, 8, S8-S12. https://doi.org/10.1016/j.ijregi.2023.03.011

[iv] Murata Y, Fujii A, Kanata S, et al. Evaluation of the usefulness of saliva for DNA methylation analysis in cohort studies. Neuropsychopharmacol Rep. 2019;39(4):301-305. doi:10.1002/npr2.12075

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We are excited to see that the Isohelix RapiDri Buccal Swab Kit has been selected as the sample collection method for an Australian study investigating the effects of peanut butter supplementation on physical function, cognitive function, body composition, nutritional status, and DNA telomere length in older adults.

Alongside the DNA analysis, participants will undergo various physical and cognitive function assessments, body composition, and nutritional status analyses.

Once available, the results will indicate whether daily peanut butter intake improves physical function, cognitive health, and overall well-being in older adults.

We can’t wait to see the results of the study when they are published!

For more details on the study, click here.