Fig. 1.

Pathophysiology of airway disease in MPS IVA.

(A) Diagram to illustrate the pathophysiology for airway and respiratory disease in MPS IVA. Note the combination of GAG accumulation into tissues organs results in both obstructive and restrictive disease effecting both the lower and upper airways. A positive feedback loops develops from thick, copious secretions, airway narrowing and chronic respiratory infections. Image kindly reproduced with permission from Tomatsu et al. (2016). (B) The second image depicts a severely diseased traches in a 19 year patient with MPS IVA who had not received ERT treatment. Note the profound tortuosity and tracheal buckling (solid white arrow) that is pathognomic of MPS IVA; in this case the narrowest point of the trachea is 2 mm.