Asthma and airways collapse in two heritable disorders of connective tissue.

Abstract

This study investigated the clinical impression that there was an increased prevalence of respiratory disorders in both the Hypermobility Syndrome (HMS)/Benign Joint Hypermobility Syndrome (BJHS) and Ehlers-Danlos Syndrome (EDS), compared with the normal population. A questionnaire was distributed to 509 subjects (221 healthy controls, 126 HMS, 162 EDS) who documented respiratory symptoms and previously diagnosed respiratory and atopic disorders. A subgroup of 157 responders underwent full clinical and serological assessments, and 57 subjects were assessed physiologically. A significant increase in the frequency of a wide range of respiratory symptoms and reduced exercise tolerance was observed in subjects with both HMS and EDS compared with controls. In particular, there was an increased prevalence of asthmatic symptoms (HMS: OR 2.4, 95% CI 1.4-4.1, p = 0.002; EDS: OR 3.1, 95% CI 1.8-5.2, p<0.001) and atopy (HMS: OR 2.7, 95% CI 1.6-4.5, p<0.001; EDS: OR 2.6, 95% CI 1.6-4.4, p<0.001), which was subsequently confirmed by clinical assessment. Pulmonary physiological studies revealed increased lung volumes, impaired gas exchange and an increased tendency of both the lower and upper airways to collapse. We have demonstrated, for the first time, that individuals with HMS/BJHS and EDS have respiratory symptoms in association with various pulmonary physiological abnormalities. The increased prevalence of asthma may be due to linkage disequilibrium between the genes causing these conditions or a function of the connective tissue defect itself. In the non-asthmatic population, changes in the mechanical properties of the bronchial airways and lung parenchyma may underlie the observed increased tendency of the airways to collapse.