Exocytosis is impaired in mucopolysaccharidosis IIIA mouse chromaffin cells

► Elevated heparan sulphate storage in MPS IIIA chromaffin cells. ► Catecholamine secretion was reduced in MPS IIIA chromaffin cells. ► Fusion pore kinetics was unaltered in MPS IIIA chromaffin cells. ► Calcium entry was unaltered in MPS IIIA chromaffin cells.