An endotype is a subtype of a health condition, which is defined by a distinct functional or pathobiological mechanism. This is distinct from a

phenotype In genetics, the phenotype () is the set of observable characteristics or traits of an organism. The term covers the organism's morphology (physical form and structure), its developmental processes, its biochemical and physiological propert ...

, which is any observable characteristic or trait of a

disease A disease is a particular abnormal condition that adversely affects the structure or function (biology), function of all or part of an organism and is not immediately due to any external injury. Diseases are often known to be medical condi ...

, such as development, biochemical or physiological properties without any implication of a mechanism. It is envisaged that

patient A patient is any recipient of health care services that are performed by Health professional, healthcare professionals. The patient is most often Disease, ill or Major trauma, injured and in need of therapy, treatment by a physician, nurse, op ...

s with a specific endotype present themselves within phenotypic clusters of diseases. One example is

asthma Asthma is a common long-term inflammatory disease of the airways of the lungs. It is characterized by variable and recurring symptoms, reversible airflow obstruction, and easily triggered bronchospasms. Symptoms include episodes of wh ...

, which is considered to be a

syndrome A syndrome is a set of medical signs and symptoms which are correlated with each other and often associated with a particular disease or disorder. The word derives from the Greek language, Greek σύνδρομον, meaning "concurrence". When a sy ...

, consisting of a series of endotypes. This is related to the concept of disease entity.

Disease entity

The main concept in

nosology Nosology () is the branch of medical science that deals with the classification of diseases. Fully classifying a medical condition requires knowing its cause (and that there is only one cause), the effects it has on the body, the symptoms th ...

is the disease entity. Normally there are two ways to define a disease entity: Manifestational criteria and causal criteria. * Manifestational criteria. These are a set of criteria based on signs, symptoms and laboratory findings that define a disease. They define a disease by its symptoms and medical findings. * Causal criteria. These are a causal chain of events that defines the disease describing how it develops. They describe the disease by its

etiology Etiology (; alternatively spelled aetiology or ætiology) is the study of causation or origination. The word is derived from the Greek word ''()'', meaning "giving a reason for" (). More completely, etiology is the study of the causes, origins ...

. Following

Fred Gifford Fred Gifford (a.k.a.) Freddy Giff is a professor and the associate chair of the philosophy department at Michigan State University. He earned his Ph.D. at the University of Pittsburgh The University of Pittsburgh (Pitt) is a Commonwealth System ...

, these criteria lead one to view any disease entity in three different forms: * Disease as symptoms: The disease is defined by the symptoms and signs that it produces. In fact, it can be said that the disease is the collection of them. It is the classical way to define a disease or a condition. * Disease as state: The disease is not defined by a set of symptoms but by the underlying state of the body, including pathological tissues, abnormal cells and any other general medical findings. This kind of definition allows the researchers to speak about

silent disease Asymptomatic (or clinically silent) is an adjective categorising the medical conditions (i.e., injuries or diseases) that patients carry but without experiencing their symptoms, despite an explicit diagnosis (e.g., a positive medical test). Pre ...

s, which cannot be considered as such by the previous definition. Proponents of this kinds of entity are for example

Rudolph Virchow Rudolf Ludwig Carl Virchow ( ; ; 13 October 18215 September 1902) was a German physician, anthropologist, pathologist, prehistorian, biologist, writer, editor, and politician. He is known as "the father of modern pathology" and as the founder o ...

. * Disease as a process: In the 20th century, a third concept of disease has appeared, based on the works of

Caroline Whitbeck Caroline may refer to: People * Caroline (singer) (born 1981), Japanese glitch pop musician * Caroline (given name), a feminine given name * J. C. Caroline (1933–2017), American football player * Jamie Caroline (born 1999), British racing driv ...

in 1977. Whitbeck proposed that a disease may be defined by the clinical course of a set of untreated patients. She also argues that diseases are complex processes of which both clinical and underlying pathophysiological manifestations are proper parts (as contrasted with effects). Following again F. Gifford, in fact each of the previous definitions can include the

aetiology Etiology (; alternatively spelled aetiology or ætiology) is the study of causation or origination. The word is derived from the Greek word ''()'', meaning "giving a reason for" (). More completely, etiology is the study of the causes, origin ...

or can be aetiologically agnostic. Other authors simply continue with the classification of Whitbeck, leaving just three kinds of definition (clinical, pathological and aetiological). It is important to note that a real-world definition is normally a hybrid between these above kinds, and an endotype should use all three of the descriptors - including aetiology - to ensure specificity.

Notes

References

* {{Cite journal , last=Anderson , first=GP , s2cid=13161535 , title=Endotyping asthma: new insights into key pathogenic mechanisms in a complex, heterogeneous disease , journal=Lancet , date=20 September 2008 , volume=372 , issue=9643 , pages=1107–19 , doi=10.1016/s0140-6736(08)61452-x , pmid=18805339 Medical terminology

Disease entity

See also

Notes

References