Syndrome

A syndrome, in medicine and psychology, is the collection of signs and symptoms that are observed in, and characteristic of, a single condition. In medical genetics, a syndrome refers specifically to medical condition where the underlying genetic cause has been identified, and the collection of symptoms is pathogenetically related. Examples of syndromes in medical genetics include: Down syndrome, Stickler syndrome, and Williams syndrome. Conditions such as Toxic shock syndrome and Acquired Immune Deficiency Syndrome are examples of non-genetic syndromes. If the underlying genetic cause is not known, the condition is referred to as an "association". By definition, an association shows that the collection of signs and symptoms occurs in combination more frequently than would be likely by chance alone. Syndromes are often named after the physician or group of physicians that discovered them or initially described the full clinical picture. Recently, there has been a shift towards naming conditions descriptively or according to their underlying cause, however the "eponymous" syndromes often persist in common usage.

Definition
A syndrome can refer to the traits that suggest the presence of a disease, or indicate a greater likelihood of developing the disease. The term syndrome derives from the Greek σύνδρομον, meaning "concurrence".

Medicine
In medicine and psychology, a less specific definition of syndrome is used, which describes a collection of symptoms and findings without necessarily tying them to a single identifiable pathogenesis. The more specific definition employed in medical genetics describes a subset of all medical syndromes.

Medical genetics
In the field of medical genetics, the term "syndrome" is traditionally only used when the underlying genetic cause is known. Thus, Trisomy 21 is commonly known as Down syndrome. Until 2005, CHARGE syndrome was most frequently referred to as "CHARGE association". When the major causative gene (CHD7) for the condition was discovered, the name was changed. The consensus underlying cause of VACTERL association has not been determined, and thus it is not commonly referred to as a "syndrome".

Naming
There is no set common convention for the naming of newly identified syndromes. In the past, syndromes were often named after the physician or scientist who identified and described the condition in an initial publication, these are referred to as "eponymous syndromes". In some cases, diseases are named after the patient who initially presents with symptoms. There have been isolated cases of patients being eager to have their syndromes named after them, while their physicians are hesitant. When a syndrome is named after a person, there is some difference of opinion as to whether it should take the possessive form or not (Down syndrome vs. Down's syndrome). North American usage has tended to favor the non-possessive form, while European references often use the possessive. Even in Europe, there has been a trend away from the possessive form, over the period between 1970 and 2008.

History
Ibn Sina (Avicenna, 980-1037), in The Canon of Medicine, pioneered the idea of a syndrome in the diagnosis of specific diseases. The concept of a medical syndrome was further developed in the 17th century by Thomas Sydenham.