https://arstechnica.com/tech-policy/2021/11/theranos-tests-detected-prostate-cancer-marker-in-prostateless-women/

Around 2016, Theranos’ fourth lab director, Kingshuk Das, noticed a problem. He was analyzing data from the company’s diagnostic devices when he saw results from tests for prostate-specific antigen, or PSA. PSA is used to detect prostate cancer in men, and except in rare cases, it’s not present in women’s blood. Except, here it was, appearing in women’s test results.

Das took his PSA findings to CEO Elizabeth Holmes. “Females should generally not have PSA detectable,” Das told the jury in Holmes' criminal trial yesterday.