Discovery of bitter-taste gene is sweet

Variations in a gene on chromosome 7 seem to explain why people can differ in their sensitivity to bitter substances.

The capability to sense bitterness may have evolved because it keeps animals from eating harmful plants. “We have a sense of bitter taste to protect us from ingesting toxic substances,” says Dennis Drayna of the National Institute on Deafness and Other Communication Disorders in Bethesda, Md.

For decades, taste researchers have used a chemical called phenylthiocarbamide (PTC) to assay a person’s capability to sense a bitter taste. About 70 percent of people find PTC intensely bitter, but the rest can barely taste it.

Scientists know that this difference in sensitivity is inherited, but they’ve struggled to find the gene or genes responsible. In the Feb. 21 Science, Drayna and his colleagues pinpoint a single crucial gene they discovered by studying large families in Utah. The gene encodes a protein that is a component of a known bitter-taste receptor in taste buds. Drayna’s group found that family members who could sense PTC had a different version of the gene from those who couldn’t sense the chemical.

Other researchers testing people with a different chemical have argued that some people are extraordinarily sensitive to bitter substances. These so-called supertasters may risk certain diseases because they avoid eating vegetables, the scientists theorize (SN: 7/12/97, p. 24:; SN: 3/1/03, p. 142: Available to subscribers at Good taste in men linked to colon risks).

Drayna isn’t convinced that supertasters exist, but he plans to investigate whether the gene variants his group identified can help resolve that issue.


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