Weight loss surgery may alter fatty liver disease genes

07 August 2013

Weight loss surgery may have additional benefits for obese patients who have a condition called fatty liver disease, new research has shown.

Fatty liver disease most commonly occurs in people who are overweight or obese, with figures suggesting that about one in five people in the UK have early forms of the condition.

In most cases, people only carry small amounts of fat in their liver and there are no symptoms; but the fat can build up and may ultimately lead to scarring of the liver and organ failure.

Scientists at University Hospital Dresden in Germany have now found that weight loss surgery - such as gastric bypass surgery - can actually help to reverse the symptoms of fatty liver disease, in addition to the more obvious beneficial effects on people's weight.

The research team studied 45 morbidly obese patients with various stages of non-alcoholic fatty liver disease, as well as 18 healthy volunteers.

They analysed liver samples from all of the patients in order to study their gene expression - whether certain genes were switched on or off.

In addition, they looked at patterns of DNA methylation, which is a chemical modification on DNA that does not alter the actual genetic sequence but regulates whether or not certain genes are switched on or off.

The researchers found differences in the expression of nine genes - all of which were involved in metabolism and insulin signalling - between patients with non-alcoholic fatty liver disease and those without the condition.

Patients with fatty liver disease showed altered patterns of methylation on various genes, as well as enriched binding sites for proteins that affect gene expression.

"These DNA modifications may point to the first steps in the evolution of the disease and may thus direct future research," said senior author Dr Joseph Hampe, from University Hospital Dresden.

"In the very long term, they may lead to new therapeutic options."

When the researchers compared biopsies from before and after weight loss surgery, they confirmed that many of the methylation changes that were associated with fatty liver disease were reversed following the procedure.

The study - which is published in the journal Cell Metabolism - suggests that gastric bypass surgery and other forms of weight loss operation may have DNA-altering effects that benefit patients with non-alcoholic fatty liver disease.

While this is the first time such effects have been observed, weight loss surgery is already known to have benefits beyond those for the waistline.

For instance, studies have shown that surgical weight loss can help to reverse the symptoms of type-2 diabetes, effectively bringing about remission in patients with this lifestyle-related disease.

A recent study in the journal Science shed light on these effects, revealing that gastric bypass surgery causes the intestines to work harder, use more sugar and thus help to keep blood sugar levels under control.

Researchers at Boston Children's Hospital calculated that up to 64 per cent of the change in blood sugar levels following gastric bypass surgery may be due to the intestines' increased energy needs.

Posted by Jeanette Royston


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