Most people can smell over 10,000 different odors. The smell of fresh grass (Cis-3-hexen-1-ol) is a pretty popular odor. This organic compound is also present in many foods and beverages, such as wine, olive oil, vegetables, and green tea. However, some people simply cannot detect this particular smell to the same extent because genetic and environmental factors control odor perception.
The most studied gene in terms of odor detection, is the odorant receptor (OR) gene, one of the largest gene families in the human genome, having 855 members. Because variation in specific odorant receptors can affect distinct odor perception, the odorant receptors are prime candidates for investigating the genetic basis of odor perception. The specific aim of this research was to conduct an investigation into a possible genetic basis for cis-3-hexen-1-ol odor perception.
In this study, voluntary participants were employees at the Mt Albert campus of Plant & Food Research (then HortResearch) in Auckland, New Zealand. Participants (n=48) were presented with two samples: one containing filtered water (noise) and the other cis-3-hexen-1-ol at the highest concentration (19.2 ppm; signal). This kind of warm up is required in order for participants to recognize the signal they are looking for and differentiate it from the noise sample. Immediately following warm-up, participants moved to the sensory booths, and samples were presented one by one. Each session was divided into four parts, each representing a single replication of the eight samples (one noise sample and seven signal samples representing the seven different concentrations of cis-3-hexen-1-ol). They were asked if the sample was a signal or noise and their level of certainty (sure or unsure). From these data, participants’ detection thresholds were calculated. The genetic association test identified genetic variants related to the green leaf odor sensitivity, including rs7938698 in the NAV2 gene, rs2148065, rs4293040, and rs10272488. The NAV2 gene is expressed in the brain during the development of the nervous system in embryos and is involved in the development of sensory organs, including the olfactory system.
Uncovering significant associations with the NAV2 gene is exciting because it adds to the few existing reports on differences in downstream components in the olfactory signaling pathway. However, there are some limitations similar to other studies, one of those is the small sample size. The small sample size may limit the discovery of significant association with a SNP that was located within the coding region of an OR gene in this study. Read more about the study here:
Are you interested in learning more about your genetic tendency for sensitivity to fresh-cut grass scent? You can login to your Genomelink YOUR TRAITS to see this new genetic trait.