Have you ever tried a fragrance that other people say is amazing, but you think it smells awful like a wet ashtray, or it smells like nothing at all? You may have musk anosmia like me. I have done a lot of personal research on this, and here is what I have found...
Musk anosmia is a genetic condition where the person is unable to perceive certain musks. It's a genetic variation that affects at least 7% of the US population. Because of the size of the molecules, if a fragrance contains macrocyclic musks, I am unable to perceive it AND any of the other notes in the fragrance. The exception is sandalwood. If the fragrance contains sandalwood then that is all I smell, and it is VERY strong. It comes off smelling like a wet ashtray. Without musk, the sandalwood is more subdued so it smells nice.
There are many types of musk, and most fragrances contain one or more of them. The human olfactory receptor OR5AN1 is sensitive to macrocyclic and nitro musks (muscone, civetone, habanolide, ambrettolide), but not polycyclic (galaxolide, fixolide, tonalide) or alicyclic musks. Someone with a genetic variant in OR5AN1 will likely experience musk anosmia when exposed to polycyclic or alicyclic musks. I've found that once my musk anosmia is triggered, all fragrances will smell like nothing, unless they contain sandalwood, in which case they will smell like wet ashtray. To clear this temporary anosmia, I can move into clear air and sniff peppermint, cloves, or tea tree oil for 10 minutes. Then my olfactory senses are 'reset'.
Some fragrances that I can't smell are Swiss Arabian Musk Malakai, Initio Musk Therapy, LaPerla Invisible Touch, LaPerla Once Upon a Garden, Xerjoff Damarose (this one broke my heart), and Baccarat Rouge 540. Fragrances that smell like wet ashtray to me always contain musk and sandalwood, like Molinard Habanita and Nishane Ani.
According to this article, the presence of musk can change the intensity of the perception of some notes, which is why fragrances containing musk and sandalwood will smell like only sandalwood, and the sandalwood is intense so it smells like wet ashtray.
In summary, OR5AN1 is a crucial macrocyclic and nitro musk receptor in humans, and genetic variation appears to cause variable responsiveness to macrocyclic musks in in-vitro assay. Significant differences were observed among OR5AN1 genotypes in musk odor perception; genetic variation of OR5AN1 affects the perceived intensity of exaltolide and ethylene brassylate, and the detection threshold for muscone.