Incidentalomea neologism that denotes incidental findings in genetic tests and, according to the term’s originator, “threatens to undermine the promise of molecular medicine.”

Radiologists have long used the word incidentaloma to refer to masses or tumors they happen to see on scans while looking for something else. In a recent study at the Mayo Clinic in Rochester, Minn., for example, among 1,426 imaging exams, 567 revealed incidental findings. Of those cases, only 35 (6.2%) led to additional imaging, biopsies or surgery, and only 6 cases demonstrated a direct benefit from the testing. By recommending that patients get checked out, radiologists often subject patients to unnecessary worry and the health care system to wasted money and resources; but if they don’t, they place that 6.2% of patients at risk.

Isaac Kohane, who coined the term incidentalome and is co-director of the Center of Biomedical Informatics and Division of Health Sciences Technology at Harvard Medical School, charges that genomic testing has introduced the same problem but on an even larger scale. The incidentalome (the suffix “-ome” signifies the entire universe of these findings, much as it is used for such biological systems as genome and proteome) includes false positives, which are bound to happen in tests for single-gene diseases for which the patient has no history or symptoms. Doctors often order these tests “just in case” or as part of a much larger battery. It also includes insignificant findings, as in the case of mail-order genome tests, which scan thousands of genes and pinpoint variants that heighten risks of certain diseases, but which often are no cause for concern.