Researchers Identify Genetic Variations Linked to Oxygen Drops During Sleep
Researchers have identified 57 genetic variations of a gene strongly associated with declines in blood oxygen levels during sleep. Low oxygen levels during sleep are a clinical indicator of the severity of sleep apnea, a disorder that increases the risk of heart disease, dementia and death. The study, published Oct. 24 in the American Journal of Human Genetics, was funded by NHLBI.
“A person’s average blood oxygen levels during sleep are hereditary, and relatively easy to measure,” said study author Dr. Susan Redline of Brigham and Women’s Hospital, a professor at Harvard Medical School. “Studying the genetic basis of this trait can help explain why some people are more susceptible to sleep-disordered breathing and its related morbidities.”
When we sleep, the oxygen level in our blood drops, due to interruptions in breathing. Lung and sleep disorders tend to decrease those levels further, and dangerously so. But the range of those levels during sleep varies widely between individuals and, researchers suspect, is greatly influenced by genetics.
Despite the key role blood oxygen levels play in health outcomes, the influence of genetics on their variability remains understudied. The current findings contribute to a better understanding, particularly because researchers looked at overnight measurements of oxygen levels. Those provide more variability than daytime levels due to the stresses associated with disordered breathing occurring during sleep.
The researchers analyzed whole genome sequence data from NHLBI’s Trans-Omics for Precision Medicine program. To strengthen the data, they incorporated results of family-based linkage analysis, a method for mapping genes that carry hereditary traits to their location in the genome. The method uses data from families with several members affected by a particular disorder.
“This study highlights the advantage of using family data in searching for rare variants, which is often missed in genome-wide association studies,” said Dr. James Kiley, director of NHLBI’s Division of Lung Diseases. “It showed that, when guided by family linkage data, whole genome sequence analysis can identify rare variants that signal disease risks, even with a small sample. In this case, the initial discovery was done with fewer than 500 samples.”