mast cell activation syndrome MCAS Mast cell activation syndrome (MCAS) is one type of mast cell activation disorder (MCAD), and is an immunological condition in which mast cells inappropriately and excessively release chemical mediators, resulting in a range of chronic symptoms, sometimes including anaphylaxis or near-anaphylaxis attacks. MONDO_0100004 disorder of mast cell activation mast cell activation disease https://en.wikipedia.org/wiki/Mast_cell_activation_syndrome Liwei Wang, Oliver He mast cell activation disorder