The World Health Organization (WHO) calls it a "double burden" of disease and says: "It is not uncommon to find under-nutrition and obesity existing side-by-side within the same country, the same community and the same household".

BBC: Obesity pandemic

People who have one or more copies of the bad gene have at least double the risk of the disease.

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But they did find that people with anxiety had more than double the risk of heart disease and two-and-a-half times the risk of suffering a heart attack.

CNN: Study: Anxiety in youth linked to heart attacks later on

Bad diets and a lack of exercise are expected to almost double the prevalence of the disease by 2015, and drug companies are pushing potential treatments to market.

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Once a variant looks like it might be a cause of disease, it is double-checked using Sanger sequencing, the older, more expensive process that was used to create the original draft of the human genome a decade ago.

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They found that children raised by one parent had more than double the risk of suicide attempt and alcohol-related disease.

BBC: 'Suicide risk' for lone parent kids

Jeremy Morris found in the 1950s that London's double-decker bus drivers were more likely to die from cardiovascular disease than the bus conductors, and that government clerks were more likely to die than mail carriers.

CNN: Sitting for hours can shave years off life

She told them she was perfectly healthy, but the surgery was adamant her records showed she was a heavy smoker and suffered from Alzheimer's Disease, a kidney condition and had undergone a hysterectomy and a double hip replacement.

BBC: Mary Kerswell

Diadexus drew headlines last month when it helped identify what may be a new risk factor in heart disease: a little-known protein produced by the body that can double the risk of heart attacks.

FORBES: Divining Disease