A Federation planet housing the Darwin Genetic Research Station, whose engineered children unwittingly caused a fatal ageing disease in the Next Generation episode Unnatural Selection.
Gagarin IV is the location of the Darwin Genetic Research Station, run by Dr Sara Kingsley. It appears in Unnatural Selection (2365).
The Enterprise-D finds the supply ship USS Lantree adrift with its whole crew dead of extreme old age. Its last port of call was Gagarin IV, where the scientists are now ageing rapidly too. They beg Picard to save their genetically engineered children, who seem healthy.
Dr Pulaski examines one boy aboard a shuttle and is infected. The children's aggressive immune systems had reacted to a mild flu brought by a Lantree crewman and produced an antibody that alters human DNA. Pulaski and the scientists are cured by using the transporter to restore their original genetic patterns, but the children must stay isolated.