NEW YORK (GenomeWeb News) – A research team has pooled data on more than 3,000 patients and determined that patients' genetic background provides a better method of assessing their potential lung function than current standard benchmarks, such as self-reported race or ethnicity.
The researchers, led by the University of California, San Francisco, and Northwestern University, used data from five large-scale, independent health studies with self-identified African American populations to examine the impact of genetic ancestry on lung function. The team, which published its findings in the advance online edition of the New England Journal of Medicine, found a significant link between patients with African ancestry and pulmonary measurement in both men and women and across all ages.
"Since genetic ancestry improves our definition of normal lung function, it may be relevant for determining the severity of all lung diseases, as it was for asthma in this study," Rajesh Kumar, an associate professor at Northwestern University's Feinberg School of Medicine and lead author on the paper, said in a statement.
The study included patient data from the Coronary Artery Risk Development in Young Adults (CARDIA) study; the Health, Aging, and Body Composition (HABC) study; the Cardiovascular Health Study (CHS); the Study of Asthma Phenotypes and Pharmacogenomic Interactions by Race-Ethnicity (SAPPHIRE); and the Study of African Americans, Asthma, Genes, and Environments (SAGE). Study participants were between the ages of 18 and 93.
Currently, self-identified race is used as a factor in determining a normal range of pulmonary function. However, since many populations are admixed, the authors of the study hypothesized that self-identified racial and ethnic categories may misclassify people with respect to the "normal" range of physiological measures and could lead to inaccuracies in evaluating individual pulmonary function and determining population-specific disease prevalence and severity.
In this particular study, the researchers aimed to find out if the genetic percentage of African ancestry is associated with lung function and whether using such genetic data could improve predictions of lung function among persons who identify themselves as African American.
The investigators first estimated ancestral admixture in the CARDIA study from genome-wide genotyping data using an Affymetrix Genome-Wide Human SNP Array 6.0. They used an admixture software program to estimate ancestry from the SNPs. They also genotyped ancestry-informative markers from the other studies and used the software program Structure to estimate the percent African ancestry in participants.
The team used linear regression models to assess the associations of genetic ancestry with measures of lung function, after controlling for age, sex, lifetime pack-years of smoking, BMI, height, square of height, and study site.
"We found an association between genetic ancestry and lung function among subjects who identified themselves as African American; specifically, the percentage of African ancestry was inversely associated with lung function in three independent cohorts across a wide range of ages," the researchers wrote. However, they noted that the "relative contribution of genetic ancestry is likely to be smaller among older persons who have had a greater cumulative exposure to environmental factors that adversely affect lung function."
Furthermore, the authors noted that environmental factors such as premature birth, prenatal nutrition, and socioeconomic status may also play an important role in the association between lung function and ancestry.
The researchers said that further studies should be conducted to see if the same conclusions apply to other ancestrally defined groups and to determine if estimates informed by genetic ancestry are associated with health outcomes.