An endotype is a subtype of a health condition, which is defined by a distinct functional or pathobiological mechanism.[1] This is distinct from a phenotype, which is any observable characteristic or trait of a disease, such as development, biochemical or physiological properties without any implication of a mechanism. It is envisaged that patients with a specific endotype present themselves within phenotypic clusters of diseases.
One example is asthma, which is considered to be a syndrome, consisting of a series of endotypes.[2] This is related to the concept of disease entity.
^Lötvall J, Akdis CA, Bacharier LB, Bjermer L, Casale TB, Custovic A, Lemanske RF, Wardlaw AJ, Wenzel SE, Greenberger PA (February 2011). "Asthma endotypes: a new approach to classification of disease entities within the asthma syndrome". The Journal of Allergy and Clinical Immunology. 127 (2): 355–60. doi:10.1016/j.jaci.2010.11.037. PMID21281866.