The OGOD principle, One Gene, One Disease, expresses the idea that disease can be linked to a single gene mutation.

Over 1,200 physical and psychological disorders have so far been identified with a single gene, from Aarskog-Scott syndrome to Zellweger syndrome including cystic fibrosis, hemophilia, Huntington's chorea and sickle-cell anaemia, and most recently Alzheimer's disease, where researchers believe that they have identified a gene error which causes faults in the brain's nerve and blood supply system.

The value of identifying a relationship between any disease and a single specific gene is twofold;

- the existence of the defective gene provides a signature which simplifies the diagnosis of the disease, as it becomes possible to devise a biochemical test to confirm the prescence of the gene and therefore the disease

- there is the hope that the defective gene can become a therapeutic target, and that by correcting the defect or restoring the dysfunctional gene and so eliminate the disease or at least slow its progress.