Even though the genes responsible for blood pressure regulation remain unknown, it's widely believed ?and some previous studies in adult twins have shown ?that the genes are consistent over a lifetime, Dr. Snieder says.
"The next step is following these kids for a long period of time to see whether the genetic effects stabilize or, after another three or four years, there is another large jump in new genetic effect," he says. Despite conventional thinking, this scientist who focuses on genetics, was not totally surprised to see the novel genes show up during puberty ?although the amount of change surprised him ?but suspects gene expression may be consistent from that point onward.
"We need to know what the genes are to develop new medications and treatments and this shows that at different ages there appear to be different genes," says Dr. Snieder, who already is working to identify some genes that may influence unhealthy increases in blood pressure that occur over time.
A second finding that bears further study is that the importance of non-shared environmental influences became more important in the black twins over the four-year period, says Dr. Snieder.
Non-shared influences could mean one twin starts riding a bike to school while the other continues taking a bus or even that they start going to different schools.Environmental factors are wide-ranging ?including diet, physical activity, socioeconomic issues and stress ?and difficult to accurately measure, Dr. Snieder says.
However, if factors negatively influencing blood pressure in blacks can be identified, it could contribute to solving health disparities such as blacks tending to have higher rates of hypertension that start at a younger age, he says.