Sickle cell disease is an inherited blood disorder characterized by having hard and sticky red blood cells with misshapen form that looks like the C-shaped farm tool known as "sickle." The condition, which affects about one in every 365 black people in the United States shortens life span and causes episodes of severe pain.

People who have this disease carry two copies of the sickle cell gene variant. Those who carry only one copy of the gene variant, on the other hand, have what is called as sickle cell trait.

Health experts have long thought that individuals who are born with sickle cell gene variants are at increased risk for premature death regardless if a person carries only a single copy of the gene variant.

Findings of a new study, however, challenges this notion as researchers found that those who were born with sickle cell trait do not have increased mortality risk.

According to the U.S. Centers for Disease Control and Prevention (CDC), sickle cell trait rarely causes symptoms of sickle cell disease but those with sickle cell trait do have their setbacks such as muscle breakdown caused by intense exercise particularly in extreme temperatures.

Because of this risk, the Army, Navy and NCAA now require testing for sickle cell trait and those who are found positive for the gene are warned against dehydration and overheating.

For the new study published in The New England Journal of Medicine on Aug. 4, Lianne Kurina, from Stanford University School of Medicine, and colleagues looked at the health records of 47,944 black soldiers with known sickle cell trait status and found no link between sickle cell trait and increased risk for death.

The researchers, however, found a slightly increased risk for exertional rhabdomyolysis, the breakdown of muscle due to extreme physical exertion, in those with the trait albeit the elevated risk was only 54 percent higher than those without the sickle cell trait.

Although the 54 percent difference may sound a lot, it is far less than the 300 percent increase associated with use of ordinary prescription drugs. The heightened risk linked to sickle cell trait is, in fact, just about the same as that incurred by smoking, increasing age and obesity.

"Sickle cell trait was not associated with a higher risk of death than absence of the trait, but it was associated with a significantly higher risk of exertional rhabdomyolysis," the researchers concluded in their study.

Photo: Ed Uthman | Flickr