Have you ever wondered why some people can hike to high altitudes in a short period, or go on weekend ski trips in the mountains, without having any problems, while other people doing the same activities — even those who are physically fit — grapple with nausea, dizziness, headaches and fatigue?

Researchers at the medical center are participating in a multicenter study to find out whether genetic mutations might be the culprit in what’s known as acute mountain sickness. To find out, they’re looking for individuals who either did or did not develop symptoms of this illness during a rapid ascent to high altitude.

"The question we’re trying to answer is, does this disease process have a genetic basis? Is there something about a particular gene or set of genes that predisposes some people to get acute mountain sickness?" said Stephen Ruoss, MD, associate professor of pulmonary and critical-care medicine at the School of Medicine and a principal investigator for the study.

Researchers suspect that the answer is yes, and they have identified a group of some 20 genes they believe may be involved in mountain sickness. The 20 suspect genes are known to be regulated in part by low oxygen levels.

The findings will not only provide insight into the mechanisms at work in acute mountain sickness, but they could provide similar insight into other diseases involving low oxygen levels, including pulmonary hyptertension, strokes and heart attacks.

It is estimated that one in four people are prone to develop acute mountain sickness. In severe cases, if left untreated, the disease process can lead to cerebral edema — a swelling of the brain tissues — which can be fatal. "I’ve been a mountain climber for decades, and I’ve often wondered about the causes [of mountain sickness]," Ruoss said.

Researchers are looking to enroll participants age 18 or older who have, at any time in the past, gone from sea level to at least 8,000 feet (the altitude of most ski resorts) within a 24-hour period.

Using a bristled brush (similar to a toothbrush) that will be mailed to participants as part of an easy-to-use kit, participants will be asked to provide a sample of some cells lining the inside of their cheek. Participants will be asked to mail back the kit along with a questionnaire using a pre-paid envelope. "This is a fun study, and it’s quite easy for the participants — they don’t even have to leave home," Ruoss said.

Researchers will extract DNA from participants’ cheek-cell samples and will then compare the DNA patterns of the people who developed mountain sickness with patterns of those who didn’t.

The DNA samples will be used only for the purposes of the study.

For more information on the research or to enroll in the study, please call 725-6381 or send e-mail to ruoss@stanford.edu.