MILWAUKEE (AP) _ A 4-year-old boy who has undergone three liver transplants _ including one in which he received a piece of his uncle's liver _ was allowed to go home.

Nicholas Maurer has a condition that causes scarring and narrowing of the bile ducts, which causes bile to back up into the liver and damage it. He was released from Children's Hospital of Wisconsin on Saturday, and doctors have said they are optimistic about Nicholas' health.

Nicholas received a liver from a dead donor on Dec. 1, but that liver failed because of a clot in the artery that nourishes it.

In February, the boy received a piece of his uncle Donald Maurer's liver. That operation was said to be Wisconsin's first liver transplant from a living donor.

However, doctors became concerned a few weeks later when the ammonia level in the boy's blood began to rise, indicating liver failure. That brought about the need for the third liver transplant, at the end of February. That liver came from a child who died in a fire.