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A new study offers a possible mechanism to identify those at the greatest risk of flu and thus most need flu shots.

Catch cold often? Fault may lie in your genes

by Ajai Sreevatsan
Feb 26, 2013

The next time you catch a cold, blame your chromosomes as much as the weather.

Some of us are just hard-wired to fall prey to infectious diseases, according to new research by a Carnegie Mellon University team in Pittsburgh.

The higher risk factor is strongly linked to the length of a little-known biological marker called a telomere, a molecular cap that sits on the ends of the chromosome – resembling the metallic aglets at the tip of shoelaces.

In a study published in the Journal of the American Medical Association last week, the researchers reported that the shorter the telomere length, the greater the risk of catching upper respiratory infectious diseases.

Essentially, it is better if this molecular lid resembles a chef’s hat instead of a baseball cap.

“Our work suggests the possibility that telomere length is a relatively consistent marker across the lifespan and that it can start predicting disease susceptibility in young adulthood,” said Sheldon Cohen, lead researcher.

Telomeres are known to play a key role in cell division and serve as a biomarker for aging. Every single cell division shortens the length of the telomere, thereby placing a limit on the length of our lifespan.

Telomere length has been known to be linked to aging-related illnesses such as cancer, but the Carnegie Mellon team also found a higher susceptibility to infections in those as young as 22.

Researchers looked at the telomere length of white blood cells – which are the building blocks of the human immune system and the primary agents that fight disease-causing organisms.

“We realized that people who are vulnerable to infectious diseases could be identified this way,” said Denise Janicki Deverts, a member of the research team.

Cohen and his team measured the telomere length of white blood cells from 152 healthy volunteers aged 18-55. These individuals were then exposed to a rhinovirus, which causes a common cold, and quarantined for five days to see if they actually developed an infection.

The results showed that participants with shorter telomeres were more likely to become infected by the cold virus. Although there was no relationship between telomere length and infection among the youngest participants (ages 18-21), beginning at about age 22, telomere length started to predict whether individuals would develop an infection. As participant age increased, telomere length became an even stronger predictor.

Curt Horvath, a molecular biologist at Northwestern University, said that the study, by and large, reinforces the general advice of inoculating the elderly with seasonal flu shots. “It shows a correlation between incidence of infection and shorter telomeres, which are a sign of old cells and old age,” he said.

He said that while scientists have largely looked at telomeres in relation to aging, there could be possible future treatments for certain infectious diseases that target telomerase [the enzyme that regulates telomere length] activity in cells.

The findings are especially relevant, he said, for upper respiratory infections such as the flu.

“Part of the difficulty with the flu virus is that it mutates and changes, even during the flu season. It is a constant battle. Drugs are effective only against certain strains and the virus acquires resistance even against them," Horvath said.

"We have to continuously try and understand the underlying molecular mechanisms, how the virus hides from the immune system, and how it is able to differentiate between young and old cells, in order to come up with new molecular drugs.”