While systemic mastocytosis (SM) is considered a genetic disorder, it is not a condition that is typically inherited. Instead, it is caused by a random mutation of the KIT gene following conception. This gene is involved in how mast cells develop.
Sporadic versus inherited cases
The KIT gene mutation is not typically inherited and cannot be prevented. In extremely rare cases, more than one member of the same family can be diagnosed with systemic mastocytosis. This is due to the disease being inherited in an autosomal-dominant pattern.
A majority cases of SM are sporadic, meaning they are not inherited. SM can only be considered sporadic if it shows in a patient with no genetic or family history of SM. For the mutation to be inherited, the genetic mutation would need to be detectable in germ cells, which is not the case in sporadic cases.
Learn more about SM causes and risk factors
What is SM?
SM is a rare chronic blood disease that affects the skin and organs, and typically is seen in adults. It occurs when abnormal mast cells mutate and multiply uncontrollably. Flare-ups can be triggered by a number of things, including alcohol, spicy food, physical or emotional stress, insect bites, some anti-inflammatory drugs, friction on skin, sudden changes in temperature or physical exercise. Triggers differ from person to person.
Part of the immune system, mast cells are white blood cells that protect the body from bacteria and allergens by releasing histamine. SM causes mast cells to multiply and accumulate in the bone marrow, bones, digestive system or lungs. As a result, the body overreacts to allergens, with intense and long-lasting symptoms.
Symptoms and complications can be managed with medication, but the condition cannot be cured.
What are the symptoms of SM?
There are different variants of systemic mastocytosis with varying degrees of severity. Symptoms can range from skin-related issues such as hives, red skin lesions, a flushed face and itchy dark-colored bumps to fatigue, stomach pain, diarrhea, headache, bone pain, heart palpitations and mental health issues. The risk of anaphylaxis—a severe allergic reaction—is also high and can be life-threatening.
Diagnosis is performed via biopsy, alongside which doctors test tissue samples, blood and urine, and measure blood count and liver function.
Quality of life of patients living with SM
SM occurs in less than one person in 100,000 and affects both men and women, with an average age of 60 years at diagnosis. Often, there is a delay between the onset of symptoms and diagnosis, which can cause stress and anxiety.
Once diagnosed, learning to live with a genetic disorder can be challenging at first. Accepting the condition and learning coping strategies to manage symptoms and avoid triggers are essential to living well with SM. Medication can alleviate the symptom burden, but in the more aggressive forms of this white blood cell disorder, quality of life is significantly reduced, and life expectancy can also be affected.
