National Center for Advancing and Translational Sciences Genetic and Rare Diseases Information Center, a program of the National Center for Advancing and Translational Sciences

Monoclonal mast cell activation syndrome


Other Names:
Monoclonal MCAD; MMAS
Monoclonal mast cell activation syndrome (MMAS) is a rare immunological disorder characterized by recurrent episodes of allergy, flushing, stomach and intestinal cramping, diarrhea, wheezing, fatigue and a temporary loss of consciousness caused by a fall in blood pressure (hypotension). MMAS is very similar to systemic mastocytosis but without the itchy skin patches known as urticaria pigmentosa. Symptoms may be triggered by a number of factors, including eating, exertion, environmental conditions, emotional stress, or insect stings.[1][2] It is caused by a very small change (mutation) in the KIT gene which results in a defect of the mast cells. Treatment may include antihistamines and other medications, as needed.[2]
Last updated: 4/4/2016

If you need medical advice, you can look for doctors or other healthcare professionals who have experience with this disease. You may find these specialists through advocacy organizations, clinical trials, or articles published in medical journals. You may also want to contact a university or tertiary medical center in your area, because these centers tend to see more complex cases and have the latest technology and treatments.

If you can’t find a specialist in your local area, try contacting national or international specialists. They may be able to refer you to someone they know through conferences or research efforts. Some specialists may be willing to consult with you or your local doctors over the phone or by email if you can't travel to them for care.

You can find more tips in our guide, How to Find a Disease Specialist. We also encourage you to explore the rest of this page to find resources that can help you find specialists.

Healthcare Resources

  • The Mastocytosis Society maintains a Physician Database where you can search for physicians that specialize in Monoclonal mast cell activation syndrome.

Research helps us better understand diseases and can lead to advances in diagnosis and treatment. This section provides resources to help you learn about medical research and ways to get involved.

Clinical Research Resources

  • ClinicalTrials.gov lists trials that are related to Monoclonal mast cell activation syndrome. Click on the link to go to ClinicalTrials.gov to read descriptions of these studies.

    Please note: Studies listed on the ClinicalTrials.gov website are listed for informational purposes only; being listed does not reflect an endorsement by GARD or the NIH. We strongly recommend that you talk with a trusted healthcare provider before choosing to participate in any clinical study.

Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

Organizations Supporting this Disease

These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

Where to Start

In-Depth Information

  • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.

Selected Full-Text Journal Articles

Questions sent to GARD may be posted here if the information could be helpful to others. We remove all identifying information when posting a question to protect your privacy. If you do not want your question posted, please let us know.

  1. Akin C. Mast cell activation disorders. UpToDate. December, 2014; http://www.uptodate.com/contents/mast-cell-activation-disorders.
  2. Akin C. Mast Cell Activation Syndrome: Proposed Diagnostic Criteria. J Allergy Clin Immunol. December, 2010; 126(6):1099–104. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3753019/.