A white man who was given a new liver from an African-American donor has claimed that his skin is starting to turn black since the operation.
Semen Gendler was in urgent need of a liver after he was diagnosed with hepatitis C and cancer.
The 65-year-old inventor was told by doctors his only hope was a liver transplant.
After speaking with contacts in the United States, he arranged to fly there from his home in Krasnodar in the Krasnodar Krai, south-western Russia, to have the operation.
No details have been given about the circumstances under which a Russian was eligible for a transplant in the United States, where there is reportedly a shortage of donors.
However, an insider said it could be possible if he had a home the US, and there were options of having a partial liver transplant from a living donor or accepting a non-ideal liver which would make a transplant easier to obtain.
Mr Gendler said: "Russian doctors made it quite clear to me that if I didn't have a liver transplant I would not live.
"I do a lot of business in the US with partners in New York, and I asked them to help me arrange for the operation where if you have enough money it is possible to do it more quickly than in Russia.
"Fortunately I was able to afford the cost of the $500,000 [£325,000] operation, in Russia I would have had to wait too long for a donor."
He said that he had been initially delighted at having the liver of a 38-year-old and added that it had given him a new lease of life.
But he said he thought his former KGB colleague Igor Atamanenko was joking when he noticed that he seemed to be changing colour.
Igor told Russian media: "I noticed that his skin was getting darker. When he told me they had given him the liver of an African-American man, I guess that was probably the reason for the colour change.
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