P. C. Kathuria,
Manisha Rai,
- Senior Consultant, Department of Chest and Allergy, BLK Super Speciality Hospital, New Delhi, Delhi, India
- Associate Consultant, Department of Allergy, National Allergy Centre, New Delhi, Delhi, India
Abstract
Mast Cell Activation Disorder (MCAD) is a broad umbrella term which includes a heterogenous group of disorders characterized by the inappropriate and excessive release of mediators from mast cells. Mast Cell Activation Syndrome represents a severe and well-defined form within the broader spectrum of Mast Cell Activation Disorders. These disorders are generally divided into clonal and non-clonal categories. Clonal conditions include Systemic Mastocytosis, Cutaneous Mastocytosis, and Monoclonal Mast Cell Activation Syndrome, whereas non-clonal conditions comprise secondary MCAS, idiopathic mast cell syndromes, and Hereditary Alpha Tryptasemia. Considerable clinical overlap may occur between clonal and non-clonal presentations. Measurement of baseline serum tryptase (bST) plays an important role in diagnosing, categorizing, and monitoring patients with MCAS. Individuals with a bST concentration above 8 µg/L are commonly evaluated for HαT, which involves additional copies of the TPSAB1 gene, as well as the KIT D816V mutation. When the corrected bST value is higher than expected for the patient’s genotype and is accompanied by compatible symptoms, the findings strongly indicate systemic mastocytosis. The initial management is similar in all subjects of MCAS. HαT positive individuals should undergo life-long immunotherapy if indicated. There are KIT targeting drugs like Avapritinib in systemic mastocytosis. This review highlights a practical framework for improving the understanding and clinical management of patients affected by Mast Cell Activation Syndrome.
Keywords: Mast Cell activation disorders (MCAD), mast cell activation syndrome (MCAS), hereditary alpha tryptasemia (HαT), serum tryptase, mastocytosis, cutaneous mastocytosis, monoclonal mast cell activation syndrome (MMAS), KIT D816V, TPSAB1 gene
[This article belongs to Research and Reviews : A Journal of Immunology ]
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Research and Reviews : A Journal of Immunology
| Volume | 16 | |
| Issue | 02 | |
| Received | 02/02/2026 | |
| Accepted | 26/06/2026 | |
| Published | 04/08/2026 | |
| Publication Time | 183 Days |