While most individuals apply deodorant on a daily basis in order to prevent and combat the dreaded smelly armpits, there are actually a select few ethnic groups that do not have to. This is because they have the rare form of the ABCC11 gene, which comes in three possible genotypes GG, GA, or AA. This gene is directly responsible for the determination of whether a human has wet or dry earwax as well as whether they have osmidrosis or odor that is associated with sweat that is caused by excessive apocrine secretion. According to a study published back in 2012 in Frontiers in Genetics, the vast majority of Koreans have the rare AA genotype of the ABCC11 which does not produce sweat odor. Let’s take a look at how this gene works, what it’s molecular makeup is, and why Koreans have odorless sweat.
How Does The ABCC11 Gene Function?
The ABCC11 gene has two alleles, which means that the gene has different variant forms. An individual that has one form will have different observable results than another who has another form of the genotype. With the ABCC11 gene specifically, it has one nucleotide that differs which is called a single nucleotide polymorphism or SNP for short. The SNP in the ABCC11 gene will have 16 chromosomes at the base position, with 528 guanines (G) alleles or adenine (A) alleles. Due to there being two different allelic variants in the ABCC11 gene, humans can have three possible outcomes, either a GG, GA, or AA alleles. These three alleles are responsible for the distinct phenotypes that we produce as humans. These phenotypes are then either expressed by genotypes that have a wet or dry earwax composition and may or may not have the occurrence of osmidrosis (odor during sweating). Individuals who have the GG or GA genotype will produce wet ear wax which is sticky and brown colored and will have an acrid sweat odor. Individuals who have the rare AA genotype will produce dry ear wax that is flaky and will have a mild odor when sweating.
What Is The Advantage in Odoured Sweat Versus No Odor in Sweat?
From an evolutionary perspective, there are implications that odorless sweat may have helped Northern Eurasian populations adapt better to cold weather. In non-humans, we see that odoured sweat actually enhances apocrine secretion which is used to find, lure in, and mate with appropriate sexual selections. To put it simply, sweat that smells may play a role in who is attracted to us as mates.
The ABCC11 Gene and Ethnic Populations
The AA variant of the ABCC11 gene is frequently found in Asian populations and is rarely found in ethnicities from Africa or Caucasians. In populations out of East Asia, nearly 30-50% of those who live in Asia Minor, the Pacific Islands, Southern Asia, and Indigenous Americans do not have smelly armpits and possess the AA variant. Whereas, Koreans, about 95% of the population have the AA variant which pales the 2% of British Europeans who tested for it back in 2013.