For the last year Andy Williamson, who has polycystic kidney disease, has been living a compromised life.
In 2011, his donated kidney failed so he now has to have dialysis every day while he waits for a new organ.
Now, thanks to a social networking site, his American cousin John Williamson has come forward and offered him one of his kidneys.
Musician Andy Williamson, 44, who lives in Ashburton, Devon, said it was an amazing gift.
"We don't actually know each other that well, having grown up on different sides of the Atlantic, but we are friends on Facebook," he said.
"John saw that I was in need of a new kidney, and offered to be a living donor."
Advertising account manager John Williamson, 41, said that once he realised his cousin's plight, he had no hesitation in coming forward.
"Seeing Andy's situation online, and seeing pictures of him with his daughter Doro, I felt moved, and there was a little voice in my head that said, 'you should do this'. "
He has been having tests at Southmead Hospital in Bristol to check that his kidney would be suitable and also that he would not suffer any ill effects if he becomes a living donor.
The process is overseen by Kay Hamilton, one of the living donor transplant co-ordinators at Southmead Hospital's Renal Unit.
She spends a lot of time talking to both men to make sure they are both thoroughly aware of the risks.
"It's a really rigorous investigation process and the donor's safety is of the highest priority to us," she said.
"If anything is found to be unsuitable, whether psychologically or physically, then we stop the whole process. We'd love to give a kidney transplant to everyone who needs one, but not at any anyone else's expense."
John Williamson, who lives in Michigan and has had to take holiday from his job to come to the UK to help his cousin, plays down the sacrifice he is making.
'Gratitude and thankfulness'
"In the grand scheme of things it doesn't feel like a sacrifice," he said.
"There are very few opportunities in life to do something meaningful for somebody else.
"I have two young daughters at home, and I wanted to do something not just for Andy, who has a compromised standard of life, but for Doro as well."
Andy Williamson said it was hard to describe how he felt about what his cousin was doing for him.
"It's one of those things where it's difficult to find the words. It's a mixture of gratitude and just thankfulness that he's come forward to help," he said.
"I know from my previous transplant the difference it makes to me having a healthy working kidney, it's just indescribable. "
The other bonus is that the two cousins now have a bond.
"It's really great because it's given us an excuse to get to know each other better," the 44-year-old added.
"Even though we're first cousins we've haven't been that much in touch, because of being on separate continents, but it turns out that we have a lot in common in our life philosophies and things. It's really great to find a kindred spirit in the family."
The pair are waiting to find out if the living donation can go ahead.