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Anorexia could be caused by a genetic mutation, according to new research.A study of the DNA of more than 3,000 people found the eating disorder may be caused by mutations that interfere with the processing of cholesterol, disrupting mood and diet.
The findings, published in the journal Molecular Psychiatry, may lead to the development of drugs to treat the condition.
Sufferers starve themselves because they believe they are fat, and more than one in ten cases are fatal making it the deadliest of psychiatric illnesses. Just 30 per cent of patients make a full recovery.
Although many experts believe the condition is caused by social pressure, there is growing evidence there may also be a genetic link.
Researchers analysed genetic information from more than 1,200 anorexia patients and almost 2,000 healthy controls.
They looked for variants of genes that had already been linked to feeding behaviour or been flagged up in previous studies.
Just a handful of more than 150 genes studied showed signs of a link, but one stand out was the gene EPHX2, which controls an enzyme that regulates the burning of cholesterol.
Professor Nicholas Schork, of The Scripps Research Institute, La Jolla, California, said: ‘When we saw that, we thought we might be onto something, because nobody else had reported this gene as having a pronounced role in anorexia.’
Anorexia affects up to one in a hundred women but how it develops is still not fully understood.
Professor Schork added: ‘These findings point in a direction probably no one would have considered taking before.’
His researchers followed up with several replication studies, each using a different cohort of anorexia patients and controls, as well as different genetic analysis methods.
The scientists continued to find evidence that certain variants of EPHX2 occur more frequently in people with anorexia.
A study of the DNA of more than 3,000 people found the eating disorder may be caused by mutations that interfere with the processing of cholesterol, disrupting mood and diet
To help make sense of these findings, they looked at existing data from a large-scale, long-term heart disease study and determined that a subset of the implicated EPHX2 variants have the effect of altering the normal relationship between weight gain and cholesterol levels.
Professor Schork said: ‘We thought with further studies this EPHX2 finding might go away, or appear less compelling, but we just kept finding evidence to suggest it plays a role in anorexia.’
It is not yet clear how EPHX2 variants that cause an abnormal metabolism of cholesterol would help trigger or maintain anorexia.
But Professor Schork noted people with anorexia often have remarkably high cholesterol levels in their blood, despite being severely malnourished.
Anorexia sufferers starve themselves because they believe they are fat, and more than one in ten cases are fatal making it the deadliest of psychiatric illnesses. Just 30 per cent of patients make a full recovery
Moreover, there have been suggestions from other studies weight loss, for example in people with depression, can lead to increases in cholesterol levels.
At the same time, there is evidence cholesterol, a basic building block of cells, particularly in the brain, has a positive association with mood.
It is possible some anorexics for genetic reasons may feel an improved mood, from having higher cholesterol, by not eating.
Professor Schork explained: ‘The hypothesis would be in some anorexics the normal metabolism of cholesterol is disrupted, which could influence their mood as well as their ability to survive despite severe caloric restriction.’
Around 60,000 Britons have anorexia. Nine out of ten sufferers are women, the majority aged 15 to 25.
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