The human genome sequence will dramatically alter how we define, prevent, and treat disease. As more and more genetic variations among individuals are discovered, there will be a rush to label many of these variations as disease-associated. We need to define the term disease so that it incorporates our expanding genetic knowledge, taking into account the possible risks and adverse consequences associated with certain genetic variations, while acknowledging that a definition of disease cannot be based solely on one genetic abnormality.
Disease is a fluid concept influenced by societal and cultural attitudes that change with time and in response to new scientific and medical discoveries. Historically, doctors defined a disease according to a cluster of symptoms. As their clinical descriptions became more sophisticated, they started to classify diseases into separate groups, and from this medical taxonomy came new insights into disease etiology. For example, before the 20th century, schizophrenia and syphilitic insanity were treated as the same disease.
But by early 1900, it became evident that psychoses without associated dementia represented a separate disease for which the term schizophrenia was then coined. The definition of schizophrenia continues to evolve: from the psychiatric disease of the 1960s to an illness with a suspected genetic etiology. While the hunt is still on for the genes involved, we continue to define schizophrenia in terms of the presence or absence of "positive" and "negative" symptoms.
Diagnosis is the act of labeling someone as diseased through clinical, laboratory, and pathological findings, combined with clinical knowledge and judgment. Disease is generally considered to be an attribute of a patient, whereas diagnosis is the belief that the patient has a disease, a belief that may or may not be true. In using a single phrase to describe a set of clinical findings, important information can be effectively...