Salivary DNA Methylation Profiling: Aspects to Consider for Biomarker Identification

Abstract

Is it not more comfortable to spit saliva in a tube than to be pricked with a needle to draw blood to analyse your health and disease risk? Many patients, study participants and (parents of) young children undoubtedly prefer non‐invasive and convenient procedures. Such procedures increase compliance rates especially for longitudinal prospective studies. Saliva is an attractive biofluid providing good quality DNA to study epigenetic mechanisms underlying disease across development. In this MiniReview, we will describe the different applications of saliva in the field of epigenetics, focusing on genomewide methylation analysis. Advantages of the use of saliva and its comparability with blood will be discussed, as will the challenges in data processing and interpretation. Knowledge gaps will be identified and suggestions given on how to improve the analysis, making saliva ‘the’ biofluid of choice for future biomarker initiatives in many different epidemiological and public health studies.

Differentially methylated DNA regions in early childhood wheezing: An epigenome‐wide study using saliva

“…These two tissues are also easily accessible and appear to reflect pathologic changes in the airways during asthma development. 26 In conclusion, we have shown that higher DNA methylation in the promoter-regulatory region of PM20D1 from infant saliva was associated with the occurrence of early childhood wheezing, especially in children of atopic mothers. Directionally consistent epigenetic alteration observed in cord blood of children with respiratory allergy suggests that this modification might operate from birth, while the confirmation in blood and nasal epithelia of school-aged children indicates possibly long-term changes.…”

“…While blood may be valuable for studying common immunologic processes, nasal and saliva epithelia, being probably closer to the methylation status of the bronchial mucosa than blood or cord blood DNA methylation, are likely better surrogate tissues for studies focused on local inflammation and environmental influences in asthma. These two tissues are also easily accessible and appear to reflect pathologic changes in the airways during asthma development …”

“…Some studies, however, found asthma methylomic markers in buccal, nasal and airway epithelial cells. 17,18,20,25 As saliva is a candidate body fluid reflecting pathologic changes in the airways during asthma development, 26 we aimed at investigating the associations between infant saliva methylome and early childhood wheezing within the Italian birth cohort study NINFEA. Mothers who did not respond to this initial invitation were invited again at the end of the 18-month and 4-year questionnaire.…”

Can Genetic Testing Identify Talent for Sport?

“…Many epigenetic modifications are often both tissue specific and transient [50]; as a result, quantification would require frequent tissue sampling, which in the case of muscle would be invasive and traumatic, and in the case of other tissue, such as the heart and brain, highly impractical [51]. However, early research suggests that salivary profiling of DNA methylation markers holds promise [52], making this approach potentially more attractive and practically realistic. Influence of genetics and epigenetics on traits associated with elite performance.…”

The European Environmental Mutagenesis and Genomics Society Annual Meeting, 14–18 August 2016, Copenhagen, Denmark

“…Sabine Langie, Belgium, received the Young Scientist Award and presented a lecture on Environmental and epigenetic programming of complex diseases. Interestingly, DNA methylation markers in saliva may turn out to be a useful early marker for children predisposed for respiratory allergy .…”