Cystic fibrosis, sickle cell anemia, Tay-Sachs disease, phenylketonuria and color-blindness are diseases caused by gene
mutations. Just like the mutation of genes causes diseases, other gene mutations actually protect from and mitigate other
diseases. Both the causation and protection from diseases by genes and mutations thereof [which are a function of the human
terrain] validate the germ terrain duality theory of disease. [1-3]
The Germ-Terrain duality theory of disease states that the etiology of certain diseases/diseased states is better explained as a
complex interplay between germs and the inherent anatomical/physiological integrity of the body cells.
It argues that the etiology of certain diseases is not fully explained merely by the presence of germs (Germ Theory) or by a
mere loss of cellular integrity (Terrain Theory). As a result the prevention and treatment of such diseases should focus not
just on fighting germs but on maintaining/restoring the anatomical/physiological cellular integrity. The Germ-Terrain duality
theory is a harmonization of the current Germ Theory (popularized by Louis Pasteur) and the hitherto discarded Terrain Theory
(popularized by Pierre Bechamp).