My lede:

Dad needs a new kidney. His son, wanting nothing more than to return the gift of life his father gave him, gets tested to see whether he can donate a kidney. But the test reveals that he is not just a bad match, but also not biologically related to the man he believes is his father.

In such a situation, are physicians and other transplant professionals obliged to tell what they have learned about the paternity? If so, whom do they tell?

Although rare, wrongly attributed paternity is discovered during histocompatibility testing in 1% to 3% of all living kidney donations, according to a study of U.S. and Canadian transplant data published May 27 in the journal Transplantation.

The whole shebang.