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Human genes change with the seasons

Human genes change with the seasons

New research has found genes alter their behaviour according to the season.

Numerous health conditions are affected by the weather, such as arthritis getting worse in winter, and now scientists believe they have cracked why.

Professor John Todd of Cambridge University and his team studied 22,000 genes and discovered a quarter showed clear indications of changing with the seasons. It would seem that our system genes alter over an annual cycle in order to prepare our bodies for what's to come when the weather switches.

For example, with Britain's climate changing dramatically throughout the year, researchers found immune system genes are more active in winter. However in Iceland there are less changes in the genes due to the temperature being cold all year round. Near the equator saw immune genes step up a notch in the rainy seasons, during which people are more at risk of getting diseases such as malaria.

But Professor Todd notes our genes also have a negative impact on our bodies during these changes. They trigger inflammation to fight off infection, but too much inflammation could cause problems such as heart disease, arthritis and type 1 diabetes. This explains why certain health problems differ in severity throughout the year.

Although it's not fully clear why these transformations take place, it's believed genes are affected by environmental factors like temperature and light. Those who conducted the study, published in journal Nature Communications, put this down to prehistoric times when infections were transferred through huddling to keep warm.

"We see a rise in new cases of type 1 diabetes in January, February and March," Professor Todd explains. "And heart disease is much worse in the winter months."

These findings could help doctors treat patients more effectively in the winter by helping reduce inflammation, as well as reconsidering the ideal time for vaccinations.

Professor Todd feels some vaccination programmes, such as flu jabs which are currently held in autumn, should be moved deeper into winter when our genes are already in defence mode.

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