What this means

OR2J3 is an olfactory receptor finely tuned to cis-3-hexen-1-ol, the six-carbon alcohol that gives freshly cut grass and crushed leaves their characteristic green smell. A single amino-acid change in OR2J3 alters the receptor's binding affinity, so carriers of the variant need much higher concentrations before the molecule registers. This is one of several "specific anosmia" loci — places where one gene change quietly tunes a single facet of how the world smells.

OR2J3 is one of your smell receptors, and it's specifically tuned to a molecule called cis-3-hexen-1-ol — the green note in cut grass and crushed leaves. A single DNA change makes that receptor stick less well to the molecule, so it takes more of it before your brain notices. It's one of a handful of "specific anosmia" spots in your genome — places where one gene change quietly changes how one small slice of the world smells to you.

Caveats

• This affects one specific molecule, not your overall sense of smell.
• Many other green-leaf compounds will smell unchanged.
• Most published evidence is from European-ancestry cohorts.
• Day-to-day smell perception varies with congestion, hydration, and mood.

References

• Jaeger et al. — A Mendelian trait for olfactory sensitivity affects odor experience and food selection (Current Biology, 2013)
• McRae et al. — Genetic variation in the odorant receptors OR2J3 and OR1A1 and the perception of cis-3-hexen-1-ol (Chemical Senses, 2012)