incidental finding

An incidental finding is a genetic result you were not looking for. When a test reads a large stretch of the genome to answer one question, it may stumble upon something unrelated but important — like searching a document for one word and noticing a different, surprising line.

These findings became common as broad sequencing of the exome or whole genome replaced single-gene tests. A study aimed at, say, a child’s developmental condition might also reveal a variant raising the risk of a treatable adult cancer or heart condition in the child or a parent.

Such results raise real questions: which unexpected findings should be reported, and does a patient have a right not to know? Many programs follow agreed lists of medically actionable genes and discuss the possibility of incidental findings during consent, so people can decide in advance what they wish to learn.