Abstract
Genetic association studies require a quantitative and reliable method for odor threshold assessment in order to examine the contribution of genetic variants to complex olfactory phenotypes. Our main goal was to assess the feasibility of a portable Scentroid air dilution olfactometer for use in such studies. Using the Scentroid SM110C and the SK5 n-butanol Sensitivity Kit (IDES Canada Inc.), n-butanol odor thresholds were determined for 182 individuals of diverse ancestry (mean age: 20.4 ± 2.5 years; n = 128 female; n = 54 male). Threshold scores from repeat participants were used to calculate a test–retest reliability coefficient, which was statistically significant (r = 0.754, p < 0.001, n = 29), indicating that the Scentroid provides reliable estimates of odor thresholds. In addition, we performed a preliminary genetic analysis evaluating the potential association of n-butanol odor thresholds to six single-nucleotide polymorphisms (SNPs) putatively involved in general olfactory sensitivity (GOS). The results of multiple linear regression analysis revealed no significant association between the SNPs tested and threshold scores. However, our sample size was relatively small, and our study was only powered to identify genetic markers with strong effects on olfactory sensitivity. Overall, we find that the Scentroid provides reliable quantitative measures of odor detection threshold and is well suited for genetic studies of olfactory sensitivity.
Highlights
Human scent perception abilities are highly variable
The n-butanol olfactory threshold was evaluated in 182 participants of diverse ancestry using the Scentroid SM110C olfactometer
In this study we show that the Scentroid SM110C provides reliable quantitative estimates of odor thresholds, and would be an adequate olfactometer to explore the genetic basis of olfactory sensitivity
Summary
Human scent perception abilities are highly variable. It is well documented that variation exists between individuals and between sexes (Hoover 2010; Keller et al 2007). Several studies have identified inter-population differences in olfactory abilities (Eibenstein et al.2005; Sorokowska et al 2013; McRae et al 2013). Matching the high degree of diversity in scent perception phenotypes, there is a correspondingly large amount of genetic variation in olfactory genes. Ongoing research is attempting to link variation at the genetic level to observed phenotypic variation, gaining a deeper understanding of olfactory genetics, and of the genetic contribution to highly personalized scent perception phenotypes (see Mainland et al 2014; Schütz et al 2014; McRae et al 2013). Gene expression analysis has shown that inter-individual differences in olfactory abilities may be due to differential expression of functional OR genes in the olfactory mucosa (Verbeurgt et al 2014)
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