D816V mutation in gene c-KIT is used for qualitative detection of the mutation found in most adults (>80%) with systemic mastocytosis. Detection of the KIT D816V mutation can aid in the diagnosis of systemic mastocytosis and guide the choice of therapy since it is associated with resistance to imatinib mesylate. The KIT D816V mutation also occurs in some cases of acute myelogenous leukemia and seminoma.
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c-KIT, also known as CD117, is a protein and cell surface receptor that plays a significant role in various physiological processes, including cell growth, differentiation, and survival. It belongs to a family of receptors known as receptor tyrosine kinases (RTKs). The c-KIT receptor is particularly important in hematopoiesis (the formation of blood cells), gametogenesis (the formation of eggs and sperm), and the development of certain tissues in the body.
More than 80% of individuals with systemic mastocytosis have a mutation in the KIT gene that replaces the amino acid aspartic acid with the amino acid valine at position 816 in the protein (Asp816Val or D816V).
Mastocytosis is a rare disorder characterized by the abnormal accumulation of mast cells in various tissues throughout the body. Mast cells are a type of white blood cell that plays a key role in the body's immune response. In mastocytosis, these cells are abnormally increased in number and often contain too many granules filled with chemicals like histamine, which are released during an allergic or inflammatory response. This excessive release of chemicals can lead to a wide range of symptoms.
Mastocytosis can be divided into two main categories:
Cutaneous Mastocytosis
- This form of mastocytosis primarily affects the skin
- It is more common in children and usually presents in infancy
- The most common type of cutaneous mastocytosis is called urticaria pigmentosa, characterized by reddish-brown patches or lesions on the skin
- Patients with cutaneous mastocytosis often experience itching, flushing, and hives
Systemic Mastocytosis
- Systemic mastocytosis involves mast cell infiltration into various organs and tissues beyond the skin, such as bone marrow, liver, spleen, and the gastrointestinal tract
- It is less common than cutaneous mastocytosis and is more frequently seen in adults
- Symptoms of systemic mastocytosis can range from mild to severe, and they may include abdominal pain, diarrhea, low blood pressure, anaphylaxis, bone pain, and fatigue
- Systemic mastocytosis can also lead to complications such as osteoporosis, malabsorption, and blood disorders
Mastocytosis is often diagnosed through a combination of clinical evaluation, skin biopsies, and bone marrow biopsies. Genetic testing may also be conducted to identify specific mutations, such as the KIT D816V mutation, which is commonly associated with mastocytosis.
Treatment for mastocytosis depends on the type and severity of the disease. Common treatment options may include:
- Antihistamines to manage symptoms like itching and flushing
- Medications that target the excessive release of mast cell mediators, such as cromolyn sodium or leukotriene modifiers
- Epinephrine auto-injectors for emergency use in cases of severe allergic reactions
- Avoiding known triggers or allergens that can provoke mast cell degranulation
- In more severe cases, treatments like tyrosine kinase inhibitors or monoclonal antibodies may be considered, particularly in systemic mastocytosis
