Doctors at Okayama University Hospital began the nation's third lung transplant involving living donors Wednesday morning, hospital officials said.
Doctors at the state-run university hospital are performing the operation on a woman in her 20s, from Okayama Prefecture, who is suffering from serious lung disease, the officials said.
The doctors, led by professor Nobuyoshi Shimizu, will remove the woman's lungs before giving her the lower part of her brother's right lung and the lower part of her mother's left lung.
The woman, who received a bone marrow transplant in 1995, started having difficulty breathing the following year.
She was hospitalized in January after suffering pneumothorax. Her breathing capacity has dropped to 670 ml, or 24 percent of normal, and her doctors believe a transplant is the only treatment for her condition.
Japan's first lung transplant involving healthy donors took place at the same hospital in October 1998, followed by one at Osaka University Hospital, where a 30-year-old man received a transplant in January.
In March, doctors at Osaka University Hospital and Tohoku University's Institute of Development, Aging and Cancer Hospital conducted Japan's first lung transplants from a brain-dead donor, transplanting one lung into two women.
During the past decade, some 100 lung transplants have been performed overseas using living donors. Three Japanese teenagers are known to have gone to the United States for the operations.