While more of a phenotype than a medical condition per se, the sense of smell is regulated at least in part by the olfactory receptor genes encoding key proteins on the cells lining the nasal epithelium. A few examples of SNPs influencing olfactory sensitivity have been reported, including:
- rs6591536, a SNP in the OR5A1 olfactory receptor gene, strongly influences whether you detect (and how you perceive) the compound β-ionone, used as a key aroma in foods and beverages and added to products to give them a "floral" scent.
- rs5020278, a SNP in the OR7D4 olfactory receptor gene, is associated with how individuals perceive the smell of a testosterone-derived steroid, androstenone. This SNP is also known as T133M as it causes a change at amino acid 133 of the OR7D4 protein from threonine to methionine. [PMID 17873857]