How the ABCC11 Gene Explains an Asian Genetic Trait

Dry, flaky earwax and little underarm odor are common among people of East Asian ancestry, and both trace back to one gene, ABCC11.¹ A single-letter spelling change in that gene switches off a pump in certain sweat glands, which changes two traits at once.

What the ABCC11 Gene Does in Your Body

ABCC11 holds the instructions for a pump that sits on the surface of cells and pushes molecules out.² In the armpit, it pushes out odorless building blocks that skin bacteria later turn into smell.³ The same kind of scent gland lines the ear canal and makes part of earwax. So one pump shapes both sweat and earwax.⁴

The dry-type variant swaps one DNA letter, a G for an A, at a spot labelled 538G>A or rs17822931.⁵ A gene is read in three-letter groups, each choosing one building block of the protein, so changing one letter can swap one building block for another. Often a swap like this does little. Here, the new building block changes how the pump folds, so it folds wrongly.⁶ A misfolded protein isn’t just weaker. The cell flags the pump as faulty and breaks it down before it reaches its post.⁷ That is why the pump is nearly absent rather than half-working, and why people with two copies have almost none of the usual odor ingredients in armpit sweat.⁸

Everyone carries two copies of ABCC11, one from each parent. The dry type appears only when both copies are the A version. One working copy is enough for wet earwax, which is why dry earwax is called a recessive trait.

How to Tell Which Version You Have

Wet earwax is yellow and sticky, while dry earwax is flaky and pale or colorless.⁹ People with GG or GA have wet earwax, and people with AA have dry.¹⁰ A look at wax that has come out of the ear, then, suggests your likely genotype.

To check safely, look at wax that has worked its way out of the ear naturally rather than digging for it. Wet wax can range from honey-colored to dark brown. Dry wax looks like gray or beige flakes. Ear infections or very old wax can change the color, so judge by healthy ears.

Wet earwax cannot tell you whether you carry one working copy or two, since both look the same. And the result tells you about the pump, not about how much you sweat.

Families can surprise you. Two wet-type parents can have a dry-type child if both carry one A. A dry-type parent passes an A to every child, and siblings can differ in earwax type. Consumer DNA tests often report rs17822931 directly if you want to see your letters.

Odor follows the gene, but not perfectly. People with AA lack specific strong-smelling armpit compounds.¹¹ All genotypes, though, still make some odor from short fatty acids,¹² and the mix of armpit bacteria differs between genotypes too.¹³ So dry-type people can still smell after exercise, just less of the classic body odor. Diet, hygiene, clothing fabric and the exact mix of skin bacteria all shape how someone smells, so the gene is one influence among several.

Why the Dry Type Is So Common in East Asia

The dry-type variant is most common in Chinese and Koreans.¹⁴ It becomes rarer moving south and west across the world, so it probably arose in northeast Asia and spread from there.¹⁵ It is also one of the most different gene variants between East Asian and African populations.¹⁶ In northeast Asia, fewer than 1 in 100 people carry two working copies.¹⁷

Ancient DNA tracks the history. The variant has been found in a person who lived about 4,400 years ago in northern China.¹⁸ In Hokkaido, ancient Jomon people carried more of the wet type than the later Okhotsk people from Siberia,¹⁹ so the modern Ainu mix reflects people moving in from the mainland.²⁰ Why the variant spread so widely is debated, though selection is the leading explanation.²¹

Adaptation to cold climate is one suggested reason, but it is unproven. Less body odor may also have mattered for choosing mates. Researchers have not settled which benefit drove it. Selection is favored because the frequency is unusually high and sharply different between regions.

The variant also appears in many other populations, just at lower rates. Some Europeans and Native Americans carry two copies. Calling it an Asian trait describes frequency, not a rule, and your earwax, not your ancestry, tells your own type.

Do You Need Deodorant If You Have Dry Earwax

Only about 7% of people in northeast Asia use deodorant.²² Yet in a UK study, about 78% of AA women still used it.²³ So habit and culture drive much deodorant use, not only need. If you have dry earwax, you may be able to skip deodorant, though not everyone can.

Deodorant masks odor, while antiperspirant reduces sweat. Dry types may still want antiperspirant for wetness, and exercise sweat can still smell from fatty acids. Try a few days without and judge for yourself. Washing and wearing clean clothes still matter, because bacteria and old sweat in fabric can smell regardless of genotype.

The gene matters medically for heavy odor. People with AA have little risk of severe underarm odor,²⁴ and strong underarm odor is closely tied to the wet earwax type.²⁵ Surgery to remove scent glands is therefore generally not suited for AA people.²⁶ A gene test can help people who wrongly believe they smell avoid needless surgery.²⁷

A sudden new strong odor can come from infection or diet, and is worth a doctor’s visit. So is persistent worry about smelling when others notice nothing. Ask about genetic testing before any gland surgery; treatment for strong odor is usually non-surgical first.

Other Effects of the Gene on Health

Among Japanese women, dry-type women more often had no colostrum (the first milk after birth) at first.²⁸ When they had it, they produced less.²⁹ The breast’s milk-making tissue is related to scent glands, which helps explain why a gene active in one might matter in the other.

Dry-type mothers who see little early milk should not assume they are failing. Colostrum is small in volume for everyone at first, and frequent feeding helps milk come in. A lactation consultant can check latch and intake. The study did not measure later milk supply, so don’t assume a lasting problem.

Breast cancer evidence is mixed. In one Japanese study, women with a working copy had about 1.6 times the odds of breast cancer.³⁰ A European study found no link at all,³¹ and the gene’s activity in tumors did not differ by earwax type.³² Earwax type is not a useful guide to your breast cancer risk, and it is no reason for extra screening. Follow standard screening for your age and family history.

The working pump can push certain cancer and antiviral drugs out of cells in the lab, with up to about 6 times more resistance.³³ It can also make lung cancer cells resist one chemotherapy drug.³⁴ But these findings come from lab cells, not tested treatment decisions. Doctors do not choose treatments based on earwax type or ABCC11 status.

Dry Earwax and Ear Care

Earwax forms when gland oils mix with skin cells pushed out by the ear canal’s self-cleaning.³⁵ Wet and dry ear canals host different bacteria and fungi.³⁶ Neither type is cleaner or healthier.

The skin of the ear canal slowly migrates outward, carrying wax and dead skin cells toward the opening, helped by jaw movement when you chew and talk. In most people, wax reaches the outer ear without any help. Pushing a swab inside can reverse that flow and pack wax deeper against the eardrum, so avoid deep swabbing with either type. Ear-picking tools common in East Asia can also scratch the canal.

Wet wax is stickier and more plentiful, so it is more likely to build up and cause fullness, and it may need softening drops. Dry wax breaks into flakes that tend to fall out, so blockages are rarer but still possible. Only symptoms signal that care is needed.

Muffled hearing or fullness can mean a blockage. Pain or discharge suggests infection, not normal wax. Doctors can remove wax safely by flushing or suction.