Chronic chlamydia can change genes and gene signaling, by creating and dispersing abnormal proteins, debris, and cell parts, which attach to and change genes and gene signaling. The genetic changes can then be passed on to the next generation. A genetic abnormality may make the person susceptible to a chronic disease and can be made worse by new infections; however, an increased susceptibility to a particular chronic disease may also be due to co-infections, a long duration of infection, and the type of infections acquired within the family and from family animals.

It is unclear which came first, an immortal intracellular infection or an abnormal gene? Did the abnormal gene or gene signaling cause a chronic disease, or did an intracellular infection cause both the genetic change and the chronic disease?