Doctors at Shinshu University Hospital here on Tuesday began Japan's first "domino" liver transplant in which the donor with a diseased liver keeps a portion of the organ.
The series of operations, which involves three people, one acting as both donor and recipient, was to be completed early today, the hospital said.
In Japan, there have been four domino liver transplants in which the donor-recipient's entire liver was removed.
There have also been liver transplants in which part of a diseased liver was left in a recipient's body; Tuesday's surgery, however, marks the first time it is being done as part of a domino transplant, doctors said.
Surgeons will remove part of the liver of the donor-recipient, identified only as a man in Nagano Prefecture, and replace it with part of a relative's liver.
The removed portion of the man's liver will then be transplanted into a woman suffering from a liver tumor in Kyushu.
The remaining part of the man's own liver will be left in his body to assist the functions of the transplanted liver, because the size of the donated organ is insufficient, doctors said.
After the liver grows to a sufficient size, the remaining portion of the original organ will be removed, the doctors said.
The donor-recipient suffers from a metabolic disease in which the liver produces a protein that affects the central nervous system over a long period of time.
It takes 20 to 30 years for symptoms of the disease to occur in recipients of the livers. Otherwise, however, the organ functions normally.
The medical procedure is also performed abroad.