The 36-year-old was expected to complete his switch to Paris St Germain from Barcelona yesterday, but the move has collapsed as a result of a routine medical he took 24 hours earlier.
A stunned Thuram, who was on national team duty with Les Bleus at Euro 2008 earlier this month, confirmed at a press conference held at the Parc des Princes that doctors had detected a problem similar to the one which caused the death of his brother.
Other members of Thuram’s family have also been affected by cardiac complaints.
He will take further tests next month and still hopes to sign a one-year deal with PSG, but he admits his future is up in the air.
“It’s a complete surprise to me, I didn’t see it coming,” he said.
“If I am holding this press conference, unfortunately it’s not to announce my becoming a PSG player but to tell you doctors have detected a heart problem.
“It seems that it is the same problem that my brother had and which cost him his life on the basketball court.
“In a month or so, I should know whether I can pursue my career or if I have to stop.
“But I hope that everything can carry on as before.”
Thuram revealed that the medical he took when he completed his move to Barcelona showed no sign of the heart defect discovered this week, although he said he was told earlier in his career that there was the possibility of cardiac problems down the line.
PSG president Charles Villeneuve said Thuram was suffering from cardiac hypertrophy — the thickening of the heart walls — and that every precautionary step had to be taken when dealing with such a situation.
The club’s coach Paul Le Guen maintained he still wanted to sign Thuram, who retired from international football following France’s elimination from Euro 2008 a week and a half ago, and said all PSG could do now was wait and see.
“I was very surprised when I heard and I am very disappointed for him,” said the former Lyon and Rangers boss.
“We are going to wait for the necessary tests and continue to hope, but it is disappointing.
“He was at the top of the list of players we wanted to recruit but I am also happy that the problem has been detected now.
“It’s a real shame.”
Next season was set to be Thuram’s last in his distinguished career but his heart condition could ruin those hopes.
“I thank PSG and Charles Villeneuve for supporting me,” he said.
“We will know more in a month and I hope to play again.”