New research findings show that children with congenital central hypoventilation syndrome (CCHS) exhibit a diminished response to carbon dioxide in the blood, and that this ability fades with advancing age.
Studying the largest ever cohort of children with the rare disease, Dr. Michael Carroll, a postdoctoral fellow at the Center for Autonomic Medicine in Pediatrics (CAMP), discovered that, in many cases, their responses to various oxygen-carbon dioxide mixtures are muted but present.
The findings were recently published in the Journal of Applied Physiology.
CCHS affects breathing and the part of the nervous system that controls involuntary body processes. Patients typically take shallow breaths, especially during sleep, that result in a shortage of oxygen and a buildup of carbon dioxide in the blood. Because of this, individuals with CCHS are typically supported by mechanical ventilation systems.
“The common thought has been that they essentially have no response to dangerously low levels of oxygen or high levels of carbon dioxide, but in our study, we found the opposite to be true,” Dr. Carroll said. “They certainly do not have an adequate response to those stimuli, but they definitely have some response and that response seems to be stronger at a younger age and sort of disappears over time.”
Dr. Debra Weese-Mayer, professor in pediatrics-autonomic medicine (critical care) and principal investigator of the project, started CAMP at the Stanley Manne Children’s Research Institute as a first-of-its-kind center that has since emerged as a leader in studying the genetic basis of CCHS, rapid-onset obesity with hypothalamic dysfunction, hypoventilation, and autonomic dysregulation (ROHHAD), and sudden infant death syndrome (SIDS).
In 2003, after several years of inquiry, Dr. Weese-Mayer and colleagues were able to show that PHOX2B is the disease-defining gene for CCHS.
“We know the gene that causes the syndrome and that it is involved with the neurodevelopment of the respiratory and autonomic circuits in the brain,” Dr. Carroll said. “What we don’t know are the steps of disease development. It’s conceivable that by learning more about this age-dependent change in chemosensory response – a person’s ability to sense chemical levels within the blood – we may be able to hone in on the intermediate mechanisms.”