A British man is believed to be the only person in the U.K. diagnosed with a rare condition that causes his entire body to stiffen and collapse to the ground when startled, the Daily Mail reported.

For Andy Latham, 33, of Great Harwood, Lancashire, England, common noises like clapping, dogs barking, phones ringing, people shouting, horns honking, coughing, and even someone unexpectedly approaching him from behind without notice can be dangerous.

“I have an exaggerated startle response to the unexpected,” he told the Mail. “My whole body will seize and stiffen, causing me to fall over like a dead-weight.”

Latham was born with the disorder, known as hyperekplexia, but was not diagnosed until the age of 21, the paper reported.

“It can be very dangerous and is pretty scary,” Latham said. “One year a firework went off, my body stiffened and I fell over and banged my head.”

Hyperekplexia affects the glycine receptors in the brain causing severe reactions to unexpected noise, movement or touch. It is caused by a mutation in the fifth chromosome and has been linked by some researchers to Asperger's syndrome, according to the report.

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