- Human pathology

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Wednesday 16 July 2003

human disease


Definition: A disease is a particular abnormal condition (anomaly - anomalies ), a disorder of a structure or function , that affects part or all of an organism .

The study of diseases forms the pathology.
The classification of diseases forms the nosology.
The study of the causes of diseases forms the etiology.
The study of the mechanisms of diseases forms the physiopathology.

A disease differs from a syndrome , which is a collection of signs or symptoms that occur together. However, for historical reasons, many diseases that have been clearly identified continue to be referred to as "syndromes".

Conversely, numerous conditions of unknown etiology are referred as "diseases", whithout clearly defined causes.


The study of the causes of diseases forms the etiology.

Diseases may be caused by external factors such as pathogens, or it may be caused by internal dysfunctions, such as autoimmune diseases. The study of the causes of diseases is etiology.

Etiological classification of diseases

- genetic diseases, grouping chromosomal diseases and genic diseases
- infectious diseases caused by infections / infection and infectious agents
- dysimmune diseases caused by dysimmunity
- environmental diseases caused by environment , toxics , drugs
- nutritional diseases caused by nutritional anomalies
- degenerative diseases caused by senescence and ageing / aging
- tumoral diseases ( tumors )

Mechanisms of diseases - Physiopathology

Physiopathological classification

- developmental anomalies (malformations )
- metabolic diseases
- inflammatory diseases
- degenerative diseases / senescence
- tumoral diseases ( tumors )


These manifestation of diseaes are phenomenons (Greek: φαινόμενον, phainómenon, from the verb phainein, to show, shine, appear, to be manifest or manifest itself, plural phenomena). Phenomena are often, but not always, understood as "things that appear" or "experiences" for a sentient being, or in principle may be so.

For a clinician, a disease is associated with specific symptoms and signs.

For a pathologist, a disease causes morphological anomalies that can be seen with naked eyes ( macroscopical anomalies ) or seen at the microscopical level ( microscopical anomalies ).

Diseases in

- Diseases
- Disease localizations

- Group of diseases


- systemic diseases
- localized diseases (diseases of a structure)

See also

- communicable diseases ( infectious diseases )
- non-communicable diseases (non-communicable diseases )




- Wright A, Charlesworth B, Rudan I, Carothers A, Campbell H. A polygenic basis for late-onset disease. Trends Genet. 2003 Feb;19(2):97-106. PMID: 12547519

- Reich DE, Lander ES. On the allelic spectrum of human disease. Trends Genet. 2001 Sep;17(9):502-10. PMID: 11525833