According to a study recently published in the journal Clinical & Experimental Allergy, in people with clonal mast cellMast cell A type of white blood cell produced in the bone marrow. They help defend against infections and play a key role in allergic reactions. In SM, mast cells become overactive and build up throughout the body. disorders like systemic mastocytosis (SM) a chemical in the blood called diamine oxidase, or DAO, sharply rises during anaphylaxisAnaphylaxis A severe allergic reaction that can turn fatal without treatment. Patients with SM are at a higher risk of developing anaphylaxis.. Measuring DAO levels during anaphylaxis could help doctors diagnose patients with hidden SM.
Anaphylaxis is a life-threatening allergic reaction, often triggered by a food, medicine or insect sting. During anaphylaxis, the chemical histamineHistamine A chemical released by mast cells when they are activated. Histamine causes many of the allergy-type symptoms in mastocytosis, including flushing, itching and hives. is released in the body and causes swelling, trouble breathing, low blood pressure and sometimes death. The body also releases the enzyme (protein) DAO, which helps break down excess histamine.
The study looked at 35 people who went to the emergency room with anaphylaxis. Some had reactions to medicines, some to food and most to insect stings.
Six of the patients had a genetic change called the KIT p.D816V mutation, which is found in many people with SM. Blood tests showed that during anaphylaxis, DAO levels went up significantly in these patients, by more than 10 times the original level before anaphylaxis. Meanwhile, patients without the KIT p.D816V mutation had only small increases in DAO.
What is a KIT gene mutationKIT gene mutation Most SM cases are caused by the KIT D816V mutation. The KIT gene codes for a type of protein called a receptor tyrosine kinase, which signals mast cells to grow, divide and move.?
SM is usually caused by a sporadic mutation in the KIT gene, which codes for a protein called CD117 transmembrane tyrosine kinase. The protein is involved in the growth, survival and migration of mast cells. The most common KIT mutation associated with SM is the D816V mutation, which results in the amino acid aspartic acid being replaced by the amino acid valine in the protein chain.
Based on this finding, the researchers think that measuring DAO levels in people with anaphylaxis could help diagnose SM and other clonal mast cells disorders. “DAO is a quick and affordable screening biomarker that, in conjunction with other tests, helps identify clonal mast cell disorders in individuals with severe anaphylaxis,” the study’s authors noted.
Read more about SM testing and diagnosis
The study also found that even with high DAO levels, the body could not fully break down histamine during anaphylaxis.
In fatal cases of anaphylaxis, DAO levels were less helpful for diagnosing SM, but another chemical called tryptaseTryptase A protein enzyme that is primarily produced by mast cells and stored in small pockets within the cells, known as granules. High levels of tryptase are a key indicator of SM. could be used instead.
Future research should explore how DAO affects anaphylaxis and how it can be used to improve diagnosis of clonal mast cell disorders like SM, the researchers said.
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