A common gene mutation found in about 20% of the white population has been linked to high blood pressure.
Scientists from the University of Maryland School of Medicine in the US analysed the DNA of 542 members of the Old Order Amish community and found the version of gene STK39, which affects the way the kidneys process salt, has strong associations with increased risk of hypertension.
Scientists believe a number of genes play a role in high blood pressure but they are difficult to identify because so many other factors influence blood pressure, including diet, exercise and stress levels.
Because the Amish do not marry outside their community they are genetically homogenous. They also share a similar diet and rural lifestyle. This makes them ideal subjects for studies looking at the genetic causes of disease.
Study leader Dr Yen-Pei Christy Chang, said: "We want to determine how people with different variations of this gene respond to diuretics and other medications, or to lifestyle changes, such as reducing the amount of salt in their diet. This information might help us discover the most effective way to control an individual patient's blood pressure."
The findings are published in the journal Proceedings of the National Academy of Sciences.