Mast Cell Disease Facts: Is Mast Cell Activation Syndrome A Rare Disease?

The Disease / Tuesday, December 26th, 2017 / no comments

While mastocytosis is definitely considered a rare disease and even an orphan disease, a lot of patients with MCAS wonder if we, too, are in the same category. It depends on who you ask.

Lisa over at states pretty unequivocally that all mast cell disorders are rare:

  • Mast cell disease includes all forms of disease in which your body makes too many mast cells or those mast cells do not function correctly.
  • Mast cell disease is rare, affecting less than 200,000 people in the US.

That certainly fits with the declaration made by organizations like who list MCAS alongside mastocytosis:

Mastocytosis is a rare disorder characterized by abnormal accumulations of mast cells in skin, bone marrow, and internal organs such as the liver, spleen and lymph nodes. In the disorders of mast cell activation, mast cells are easily triggered to release their mediators, resulting in many of the same symptoms as systemic mastocytosis.

Even NORD, the National Organization for Rare Disorders recognizes the rarity of mast cell activation syndrome (MCAS) on their page dedicated to mastocytosis:

Monoclonal mast cell activation syndrome
These patients have symptoms of mast cell activation including recurrent anaphylaxis but no evidence of cutaneous mastocytosis. Their bone marrow biopsy shows 1 or 2 minor criteria for systemic mastocytosis, but does not fulfill the complete World Health Organization (WHO) criteria (See diagnosis section below).

Idiopathic mast cell activation syndrome
Patients with this disorder have episodic symptoms of systemic mast cell activation associated with elevated mast cell mediators such as tryptase, and urinary histamine or prostaglandin metabolites, respond favorably to treatment with mast cell mediator blocking drugs and have no diagnostic findings of cutaneous or systemic mastocytosis.

So the experts all agree. MCAS is a rare disease.

Or is it?

At least one expert, Dr. Afrin, believes that mast cell activation is not so rare but rather an undiagnosed epidemic. The opening paragraph in chapter five of his book, Never Bet Against Occam, says:

Early research on the epidemiology of MCAS is suggesting that as many as 14-17% of the general population is affected. That’s one out of every 6-7 individuals. Look around you right now. If this early research is correct, then if there are at least five other people in sight, odds are at least one of you has MCAS.

As we gathered for Christmas yesterday I did just that. When I looked around at my beautiful little family I saw 2 of us who are definitively diagnosed and at least two others who probably have some level of mast cell disease simmering under the surface. That’s just in my small family..

There were ten of us total and two who are diagnosed, so 1 out of 5. If the other two do have it, that’s 40% of us!

Of course that could be because mast cell disorders may be heirtable (or epigenetic). Recent research shows that it can run in families. It certainly does in mine since both my son and I have been diagnosed with it. My brother has it, too. I believe it runs through the maternal line on my side of the family and accounts for a long list of health complaints my mom, aunts, uncles, grandparents and other siblings had or have.

Most of them died not knowing what may have been the underlying cause for their illnesses and diseases.

Still, is it rare? Maybe not as rare as we think. It just seems that way. That’s why we need more #mastcelldiseaseawareness for the general public and especially for healthcare workers so they can begin to recognize this disease in their own patients and guide them to the right therapies and specialists.

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Mother. Wife. Patient. Keeper of Huskies. MCAS blogger & advocate. Living life in the mast lane with the Grand Tetons & Yellowstone as my backyard. You can also find me blogging at Life In The Mast Lane and The Empty Nest Housewife.

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