A
syndrome is a set of
medical signs and
symptoms that are correlated with each other and, often, with a specific
disease. The word derives from the
Greek σύνδρομον, meaning "concurrence". In some instances a syndrome is so closely correlated with a
pathogenesis or
etiology that
the words syndrome, disease, and disorder end up being used interchangeably for them. This is especially true of
genetically caused syndromes. For example,
Down syndrome,
Wolf–Hirschhorn syndrome, and
Andersen syndrome are disorders with known pathogeneses, so each is more than just a set of signs and symptoms, despite the
syndrome nomenclature. In other instances, a syndrome is not specific to only one disease. For example,
toxic shock syndrome can be caused by various toxins; premotor syndrome can be caused by various brain lesions; and
premenstrual syndrome is not a disease but simply a set of symptoms.