Systemic mastocytosis is a blood disorder that can affect many different body systems. Individuals with the condition can develop signs and symptoms at any age, but it usually appears after adolescence.

Systemic mastocytosis occurs when white blood cells called mast cells, which are produced in bone marrow, abnormally accumulate in one or more tissues. In most cases of systemic mastocytosis, the accumulated mast cells have a mutation in a gene called KIT. The KIT gene provides instructions for making a protein that plays an important role in development and activity of mast cells. The KIT protein stimulates chemical signaling pathways that are involved in the growth and division (proliferation) of many types of cells, including mast cells. In systemic mastocytosis, KIT gene mutations are somatic, which means they are acquired during a person's lifetime. These mutations result in a KIT protein that is always turned on (activated). As a result, signaling pathways are overactive, leading to increased production and accumulation of mast cells.

Systemic mastocytosis is estimated to occur in 1 per 10,000 to 20,000 individuals worldwide.

This condition is generally not inherited but arises from a somatic mutation in the body's cells that occurs after conception.

Published Date: October 01, 2018
Published By: National Institutes of Health