It is no easy task to get rid of an itch but scientists say the answer may be in your genes.
Itchiness is a common skin complaint
Researchers have discovered a defective skin gene in people with an inherited skin disorder, which causes itching, especially on the legs.
The findings may provide insights into other kinds of itch and could lead to new treatments.
Writing in the American Journal of Human Genetics, the team said experts do not really know what causes itching.
Chronic itching can be caused by skin disorders like eczema or can stem from deeper problems such as kidney failure or liver disease.
It can also be a serious side-effect of cancer therapies or powerful painkillers like morphine and in severe cases leads to sleep problems and scarring.
Although itchy skin is one of the most common problems seen by dermatologists, there are few effective therapies.
Professor John McGrath, from King's College London, studied a large Brazilian family who suffered from a condition called primary localised cutaneous amyloidosis (PLCA).
It affects several thousand people in the UK but is more common in other parts of the world including South America.
He found that the disorder was caused by a defective copy of a skin cell gene called oncostatin M receptor-beta (OSMR). Cells with mutant forms of the gene do not respond properly to signalling molecules which prompt an anti-inflammatory response.
Normally, itchiness would be prevented by the anti-inflammatory process.
Professor McGrath who is also president of the European Society for Dermatological Research, said the research provided a new insight into the causes of itchy skin.
He added: "We now plan to look for abnormalities of this signalling pathway in other itchy skin disorders and, most importantly, to examine how we can develop new treatments for that most common of all skin symptoms, itch."
Nina Goad of the British Association of Dermatologists said the research was an interesting development.
"Other recent research has explored the role of chemicals in the blood causing itching in eczema, but this study reveals a genetic link to an itching disorder.
"In many skin diseases, itching can be unbearable, causing sleeplessness and interfering with work, leisure and everyday life generally.
"Research that sheds light on the cause of this symptom could then pave the way for new treatments."