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 in the American Journal of Human Genetics, was funded by the National Heart, Lung and Blood Institute (NHLBI), part of the National Institutes of Health.
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. 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 the NHLBI’s Trans-Omics for Precision Medicine (TOPMed) 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.
The newly identified 57 variants of the DLC1 gene were clearly associated with the fluctuation in oxygen levels during sleep. In fact, they explained almost 1 percent of the variability in the oxygen levels in European Americans, which is relatively high for complex genetic phenotypes, or traits, that are influenced by myriad variants.
Notably, 51 of the 57 genetic variants influence and regulate human lung fibroblast cells, a type of cell producing scar tissue in the lungs, according to study author Xiaofeng Zhu, PhD, professor at the Case Western Reserve University School of Medicine, Cleveland.
