LEP and obesity due to melanocortin 4 receptor deficiency: Distal lung unit dysfunction may occur in obesity due to a number of mechanisms including: 1) compression of the airways particularly in those with central obesity; 2) alterations in membrane structure due to deposition of fat and/or collagen, increase type II cell density and increased lamellar body density; 3) changes in vascular permeability related to persistent inflammation or increased leptin; 4) airway inflammation; and 5) presence of concomitant airway disease such as asthma.[16, 18, 46–48].