Korean divers have genetically adapted to high blood pressure and the cold

Scientists from three countries have found that professional Korean Haene divers are genetically different from other Korean women, likely an inherited adaptation to constant submergence. One single nucleotide polymorphism helps them adapt to the increased blood pressure of diving, which is especially important in pregnancy. A second genetic variant is associated with sensitivity to cold. The study was published in Cell Reports.

In Korea, the profession of haene has existed for centuries. This is the name given to divers who harvest shellfish and other seafood from the seabed. Women usually dive to a depth of 10 meters and spend about 30 seconds there. The working day lasts four to five hours. The work often does not stop even during pregnancy, continuing to dive until the birth. Now the profession has become extinct, but in the last century it was often passed from mother to daughter.

Researchers from Denmark, South Korea and the United States, led by Melissa Ilardo of the University of Utah, decided to test how different Haene is from other South Korean women. First, the divers (30 people) and the other women (61 people) had their physiological parameters measured while underwater. All study participants experienced bradycardia while diving, but Haene's was significantly more pronounced (-18.8 beats per minute vs. -12.6 beats per minute).

The researchers then sequenced the DNA of all the participants to see if the divers had any genetic advantages that set them apart from the rest. The scientists found two genetic traits that set hene apart. The first single nucleotide polymorphism (rs66930627) is associated with lower blood pressure. The researchers believe it is an adaptation to the physiologic increase in blood pressure during diving and protects women, especially during pregnancy, from associated health risks.

The second genetic variant that distinguishes diving women from other Korean women was found in the gene encoding the SGCZ protein. Variations in this gene are associated with pain sensitivity, specifically pain associated with cold receptivity. The divers told the researchers that they work even in cold weather, when the water temperature is already approaching freezing.

Limitations of the study include the small sample size, as well as the limited set of metrics studied. In the future, the scientists plan to conduct experiments measuring thermoreception, as this aspect was not addressed in the work.