20 december 2012

Are you an early riser, or a night owl? Check your DNA


If you have the AA or AG genotype like most of the population the tendency is to die before 11AM, but those with the GG genotype on average died aroun 6 p.m.,

New research has discovered a genetic factor that helps to determine whether you are predisposed to get up early in the morning, or whether you like to stay up and active late at night.

Sunnybrook Health Sciences neurologist, and  University of Toronto professor, Dr Andrew Lim, lead the research which was seeking to determine if genetic mutations can account for differences in people’s circadian rhythm, or internal biological clock. In other words why some entire families tend to be early risers, while others tend to be active later into the night.  The findings were published in the November issue of Annals of Neurology.

As a byproduct of the study, the research also found out that the same genetic traits also determine whether you are more likely to die around 11AM, or around 6 PM
The study evolved out of earlier research begun 15 years ago looking at risk factors for Alzheimer’s.

As part of the study, the investigators measured sleep/wake and activity rhythms in older patients and obtained DNA from them.  They used this opportunity to search for common gene variants that might play a role in the internal biological clock. In so doing, they discovered a gene variant that is associated with as much as one hour difference in the timing of people's internal biological clock. 

(Sunnybrook vid grab) Dr Andrew Lim, lead the team that determined a genetic link to a predisposition towards early or late activity, and likely time of death.

Each individual carries two copies of this gene - one from their mother and one from their father. Most people, or 48% inherent a copy of an “early” variant, and one of the “late” variant, but 36 % have two copies of the two copies of the “early” variant, while 16% have two copies of the “late” variant.

This information could be potentially helpful in the scheduling of shift work or schooling says Dr. Lim, adding that knowin when a person is likeliest to die, can enable medical staff to act to prevent this by administering medical treatments at more optimal times, and better monitor vulnerable patient populations.

Other applications may involve scheduling of risky operations, and perhaps high performance athletes may change times for events so they are at their peak.

RCI’s Marc Montgomery contacted Dr Andrew Lim at his office at Sunnybrook Health Sciences Centre in Toronto.
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