基因变异 z-bo 2020-10-22 430

　　It is the same fish, some people think it is very fresh, some people think it is very fishy, why is this? A new genome-wide association study shows that people's sensitivity to fishy smell may be affected by mutations in the olfactory receptor genes they carry.

　　In order to explore the genetic basis of smell, researchers from Iceland's DeCode Genetics company conducted a genome-wide association study (GWAS) on more than 9,000 individuals. These people participated in the odor test at the same time, sniffing samples of six different odors. Researchers reported in Current Biology this week that they found that a mutation in the TAAR5 gene affects the perception of fishy odors, while a few mutations affect the perception of other odors.

　　The first author of the article, Rosa Gisladottir of DeCode Genetics, said: “We have found some sequence variations that affect our perception of fish, licorice and cinnamon flavors. Since our sense of smell is very important for perceiving taste, these variations may affect Do we like these foods."

　　The sense of smell plays a vital role for humans. When we have a stuffy nose, the food becomes dull and tasteless. Although there are more than 850 olfactory receptor genes in the human genome, about half are considered non-functional. However, the sequence diversity of the remaining olfactory receptor genes has increased, which indicates that the personalized combination of variations will affect the smell and intensity of people's smell.

　　In this study, Gisladottir and colleagues conducted a GWAS study on 9,122 Icelanders. These participants simultaneously completed a series of smelling tasks. They need to smell six kinds of odors, including licorice, cinnamon, lemon, fish, mint and banana through a sniff stick, and then tell the smell they smell and evaluate the intensity and pleasantness of the smell.

　　In general, the smell of fish is often rated as the most unpleasant, while the smell of mint is the most easily recognized by humans. And, as expected, people’s ratings of odor intensity decrease with age.

　　Researchers have identified variants related to smell in three loci. A missense mutation in TAAR5 is related to whether people have a strong sense of fishy smell, and three chain mutations in OR6C70 and OR6C68 are related to licorice smell. In addition, a mutation on chromosome 11 affects whether people can smell cinnamon. Subsequently, they verified the results on another 2,204 Icelanders.

　　They found that the missense mutation p.Ser95Pro in TAAR5 gene reduced the intensity of fishy smell. Participants with mutations were unable to accurately tell the fishy smell, and at the same time improved the score of the pleasantness of the smell. They often don’t use odorous items (such as stinky shoes) to describe the smell, but often use neutral or pleasant words to describe it, such as ketchup, caramel or roses.

　　Computer analysis predicts that the mutation of p.Ser95Pro may destroy the function of the protein. The researchers pointed out that the location of this variant affects a nearby highly conserved amino acid that is involved in the interaction of TAAR1 and TAAR5 ligands.

　　According to the genome clustering database, the researchers pointed out that the frequency of p.Ser95Pro mutations varies from population to population. It is 2.2% for Icelanders, 1.7% for Swedes, 0.8% for Southern Europeans, and only 0.2% for Africans. The frequencies of alleles that affect the sense of smell of cinnamon and licorice also vary from population to population, indicating that human sense of smell may still be under natural selection.