Genetic study finds link between musk, body odor and ancestral odor perceptors

07 Feb 2022 --- Olfactory genes that aid in detecting odors have “degenerated over time,” a recent study found. Some people’s reduced effectiveness of olfactory genes causes various subjective reactions to musk and body odor (BO).

Olfactory receptors (ORs) are proteins that allow for detecting various odors. The study explains that generally, 400 out of 800 OR genes are intact and approximately 30% of OR alleles (forms of a gene) function differently between two people.

Genetic variations within the olfactory gene can alter perceptions of odor.

This is according to researchers from the University of Pennsylvania, Chinese Academy of Sciences, Unilever Research & Development (Rotterdam and the UK), Rockefeller University and Tongji University.

Genetic variation and altered odor perception
A variation in the perception of odors can result in subject-specific anosmias, explains the study. Different examples include individuals lacking perceptions of particular odor compounds or varying reactions to a quality experience, pleasantness or intensity of odors. Participants rated the intensity and pleasantness of odors on a 100-point scale. 

Therefore, a larger genetic diversity in ORs will lead to a variation in odor perception, describes the researchers. 

The research characterized: “Galaxolide, a musk compound with a characterized specific anosmia.” People can only have one or some anosmias to musk, but not all the five musk compounds (macrocyclic, polycyclic, nitro, steroid-type, and straight-chain (alicyclic)). 

Additionally, a SNP (single nucleotide polymorphism, a common genetic variation) in OR51B2 is associated with trans-3-methyl-2-hexenoic acid, “a key component of human underarm odor.” The researchers have also found that this variation has resulted in anosmias. 

“All mammals use chemosensation as a means of intra-species communication…The growing evidence for chemical communication between humans suggests that body odor is of particular importance, as it may be processed differently in the brain than other odors,” explains the study. 

Examining odor perception through genome scan
Participants consisted of 1,000 (369 male, aged between 18 and 55) Han Chinese participants, and 357 (161 male, between 18 and 50) participants in New York City. 

A genome-wide scan on odor perception for ten odors was tested, two of which were musk and BO compounds. 

The newly discovered receptors were related to musk and BO “that have implications for how structurally different molecules can have similar odors,” suggests the study. 

“In 21 out of 29 examined cases, the derived allele was less sensitive to odors (72.4%; p<0.01). 13 of these 29 SNPs have been functionally validated by cell assay. Of these 13, there were 11 cases where the derived allele associated with decreased odor sensitivity (84.6%; p<0.01).”

Edited by Venya Patel