"producing disease," 1836, from French pathogénique, from Greek pathos "disease" (from PIE root *kwent(h)- "to suffer") + French -génique "producing" (see -gen). Related: Pathogenetic (1838); pathogenicity.
It is the hypothetical source of/evidence for its existence is provided by: Greek pathos "suffering, feeling, emotion, calamity," penthos "grief, sorrow;" Old Irish cessaim "I suffer;" Lithuanian kenčiu, kentėti "to suffer," pakanta "patience."
word-forming element technically meaning "something produced," but mainly, in modern use, "thing that produces or causes," from French -gène (18c.), from Greek -genes "born of, produced by," which is from the same source as genos "birth," genea "race, family," from PIE root *gene- "give birth, beget," with derivatives referring to procreation and familial and tribal groups. First used in late 18th century French chemistry (see oxygen), it probably involves a misunderstanding of -genes, as though it meant "that which produces."