A plant known as "birthwort," popular in Asian and European herbal medicine for hundreds of years, causes kidney failure and cancer. Dan Vergano at USA Today digs into the fascinating medical detective work that solved this mystery: scientists compared genetic mutations in the tissue of humans and lab mice who'd been poisoned by the plant's toxic component:



"The big clue was the plant itself," says pharmacologist Arthur Grollman of Stony Brook (N.Y.) University. "Once it was appreciated that it contained a potent kidney toxin and human carcinogen, we could get to the bottom of things."

Grollman and colleagues have unraveled a genetic signature left behind by birthwort in cases of cancers and kidney failure, as reported in the March journal of Kidney International. And in upcoming work, they report signs that use of the drug in Chinese medicines may be responsible for Taiwan's sky-high rate of kidney disease.