This information is provided by the National Institutes of Health (NIH) Genetic and Rare Diseases Information Center (GARD).
Systemic mastocytosis (SM) is a form of mastocytosis in which mast cells accumulate in internal tissues and organs such as the liver, spleen, bone marrow, and small intestines. It is typically diagnosed in adults. Signs and symptoms vary based on which parts of the body are affected. The disorder is usually caused by somatic changes (mutations) in the KIT gene. Most cases are sporadic and not inherited, but familial cases rarely have been reported.
Systemic mastocytosis can be divided into 4 main categories which are distinguished by various features:
Once a person is diagnosed, the category of SM must be determined, as treatment and prognosis differ for each.
For more information, visit GARD.