The recipient was Tim Andrews, a 66-year-old New Hampshire resident who had end-stage kidney disease and was on dialysis for more than two years.

The second person ever has received a transplant with a genetically modified pig kidney.

It was the fourth pig kidney transplant in the United States, and the first of three that will be done at Mass General as part of a new clinical trial sanctioned by the Food and Drug Administration. Two of the previous patients died shortly after the procedure, including one who was critically ill before the transplant.