You really CAN be allergic to running! Rare form of hives is caused by vibration - and clapping and bumpy bus rides can trigger the rash too 

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It may sound like the perfect answer to your exercise excuse dreams, offering a legitimate reason to park your gym wear in the cupboard.

But, an allergy to running is a real thing - and it is not pleasant, experts say.

A team of scientists have identified a genetic mutation that is responsible for a rare form of hives, which is induced by vibration.

The condition, known as vibratory urticaria, can be triggered by running, clapping your hands, towel drying, and even a bumpy bus journey.

The vibration causes a temporary skin rash, by promoting the release of inflammatory chemicals from the immune system's mast cells.

A genetic mutation determines who will suffer the rare allergy vibratory urticaria, where a person develops hives in response to vibration. It is triggered by running, clapping hands and even a bumpy bus ride

The study's findings suggest people with the the genetic mutation experience an exaggerated version of a normal cellular response to vibration.

Dr Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said: 'Investigating rare disorders such as vibratory urticaria can yield important insights into how the immune system functions and how it reacts to certain triggers to produce allergy symptoms, which can range from mild to debilitating.

'The findings from this study uncover intriguing new facets of mast cell biology, adding to our knowledge of how allergic responses occur.' 

Co-author of the study, Dr Dan Kastner, of the National Human Genome Research Institute, said the study 'underscores the tremendous potential of new genomic techniques'. 

In addition to itchy red welts at the site of vibration on the skin, people with the condition can also experience flushing, headaches, fatigue, blurry vision or a metallic taste in the mouth.   

Symptoms usually disappear within an hour, but those affected may experience several episodes per day.

Scientists at the National Institutes of Health analyzed three families for the current study.

Within those families, multiple generations experienced vibratory urticaria.

The vibration causes a temporary skin rash, by promoting the release of inflammatory chemicals from the immune system's mast cells

Mast cells, which are found in the skin and other tissues, release histamine and other inflammatory chemicals into the bloodstream and nearby tissue in response to certain stimuli - a process known as degranulation. 

To determine the potential involvement of mast cells in vibratory urticaria, the researchers measured blood levels of histamine during an episode of vibration-induced hives.

Histamine levels rose sharply in response to vibration, and subsided after around an hour, indicating that mast cells had released their contents.

The scientists also observed increased tryptase, another marker of mast cell degranulation, in skin around the affected area. 

The study's senior author, Dr Hirsh Komarrow, of NIAID's Laboratory of Allergic Diseases, said: 'Notably, we also observed a small increase in blood histamine levels and a slight release of tryptase from mast cells in the skin of unaffected individuals exposed to vibration.

'This suggests that a normal response to vibration, which does not cause symptoms in most people, is exaggerated in our patients with this inherited form of vibratory urticaria.' 

The researchers noted the first family's symptoms matched those described in another family, studied by scientists at Yale University in 1981.

Through collaboration with Yale, the NIH team obtained DNA samples from 25 members of that family.

Two family members came to NIH for evaluation, and put the scientists in contact with a third family with similar symptoms.

With the DNA samples from all three families, scientists were able to perform genetic analysis, including DNA sequencing on 36 affected and unaffected members from the three families.

They discovered a single mutation in the ADGRE2 gene shared by family members with vibratory urticaria but not in unaffected people.

'This work marks, to the best of our knowledge, the first identification of a genetic basis for a mast-cell-mediated urticaria induced by a mechanical stimulus,' said Dean Metcalfe, chief of NIAID's Laborartory of Allergic Diseases, and study co-author.

The NIH scientists now plan to study what happens to conduct further studies to better understand the disorder, and look for additional mutations to the ADGRE2 gene.