Brighton midfielder Enock Mwepu has been forced to retire from football at the age of 24 because of a hereditary heart condition.
The Premier League club said Mwepu would be at an "extremely high risk of suffering a potentially fatal cardiac event" if he continued playing.
Mwepu had recently fallen ill on a trip with the Zambia national team to Mali.
He was unable to train after arriving in West Africa last month and spent four days in hospital.
Mwepu had tests on his return to England and Brighton said the results meant the "only option" was for him to retire.