Childhood and Adult Asthma: Phenotype- and Endotype-Based Biomarkers

The concept of asthma has changed from that of a single disease entity to that of a heterogeneous disease comprising several phenotypes linked to specific endotypes. Recently, significant progress has been made in disease classification into phenotypes and biologically distinct variants (endotypes). Classification of patients into endotypes has led to precision medicine in which specific biomarkers and appropriate individualized treatments have now been identified. Despite the ongoing classification of disease endotypes, the presence or absence of a T-helper 2 (Th2) molecular signature has resulted in the association of asthma endotypes with phenotypes so as to establish responders and non-responders to inhaled corticosteroid therapy. More importantly, biologic therapies predicated on disease endotypes may in future constitute a paradigm shift from the traditional pharmacologic treatments and lead to better prognosis in moderate-to-severe forms of the disease (in which they are presently used). This book chapter aims to discuss the current concepts on asthma classification and biomarker-based diagnosis