In humans of African, Asian, European and Native American origin, all three TAS1R genes have multiple polymorphisms, which include those resulting in amino acid changes of the T1R proteins. The majority of amino acid sequence variation occurs in the N-terminus extracellular domain, where taste ligands are likely to bind to the taste receptors. TAS1R2 is particularly diverse compared with other human genes: its rate of polymorphisms is in the top 5–10% of all human genes surveyed. The high rate of TAS1R2 variation was predicted to result in variation in sweet taste perception.[95] This prediction was confirmed in a recent study, which demonstrated association of Ile191Val variant in TAS1R2 with habitual consumption of sugars in overweight and obese individuals.[96]
