Statistical tool could explain gene study ...(ler tests. Previous MCG research ide...)

Previous MCG research identified high-velocity blood flow as a risk factor for stroke and regular blood transfusions as a way to reduce that risk.

"While Dr. Kutlar is looking for the underlying genetic reasons for the higher stroke risks in this sample of patients, we will be looking for ways to identify the subpopulations in that sample," Dr. Xu says. "If population structure isn't taken into account, it could affect the validity of study results."

Researchers will use a statistical approach known as coalescent theory, which traces coding sequences of genes in a population sample to a single ancestral copy of a gene. That gene would theoretically be copied in the genetics of every member of an identical population.

For instance, two people with almost identical sets of chromosomes could differ in a very small way by one structural unit that binds their DNA. By tracing it back, researchers would reach a point where the "copied" gene would not be present. That would indicate the point where two lineages joined, Dr. Xu says.

Genetic differences among the two populations could then be tagged, subcategorized and accounted for in study results, he says.

"With the coalescent theory, we focus on the samples rather than the whole population," Dr. Xu says. "That way, we can generate samples with various levels of population structure with great efficiency using computers, which are important for large-scale genome-wide studies. Understanding the genetic basis for disease is key to prevention, diagnosis and effective treatment. Developing a method that accounts for variations in the genetics of people who are similar but distinct is crucial to better understanding the genetics of health."

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