D816V KIT mutations in Anaphylaxis
Research type
Research Study
Full title
Identification of D816V KIT mutations in patients with anaphylaxis and normal serum basal tryptase levels
IRAS ID
223281
Contact name
Susan Tadros
Contact email
Sponsor organisation
Epsom and St Helier Hospital NHS Trust
Clinicaltrials.gov Identifier
14/97, REC No
Duration of Study in the UK
2 years, 0 months, 1 days
Research summary
Summary of Research
Systemic mastocytosis (SM) is a rare disease caused by accumulation of mast cells (allergy cells). It is associated with an increased risk of anaphylaxis. >80% of patients with SM have a mutation in a gene that is involved in the survival of mast cells. This mutation is known as D816V KIT mutation.
There is a high prevalence of SM in patients with anaphylaxis after bee/wasp stings. Other causes of anaphylaxis include drugs or food. When a patient has anaphylaxis, the mast cells release a protein called tryptase which can be measured in the blood. Usually the level of this protein falls to a normal level within a few hours of the reaction. A persistently raised tryptase level suggests mast cell disorders such as SM. However, SM has been diagnosed in patients with anaphylaxis with a normal serum basal tryptase levels.This study aims to determine the frequency of D816V kit mutations in patients with anaphylaxis caused by a range of triggers.
A routinely used technique in the immunology laboratory at St Helier hospital (polymerase chain reaction) will be used to detect the presence or absence of D816V in samples previously collected (for another research project investigating anaphylaxis) from patients with anaphylaxis secondary to a range of causes.
We currently only assess for the presence of this mutation if the serum basal tryptase level is elevated in patients with anaphylaxis. This project will provide information as to whether serum basal level is sufficient for the assessment of evidence of mast cell disease of whether we should look for the presence of D816V kit mutation in patients with anaphylaxis with normal serum basal tryptase levels as well.
Summary of Results
D816V KIT mutations have been detected using two different PCR methods. A limit of detection of 1.56% was established for allele-specific PCR and 0.1% for RT-PCR with LNA mediated clamping and hybridisation probes. The sensitivity of these assays is considerably lower than the current method used by the local regional genetics centre for detection of D816V KIT (digital PCR) which has a limit of detection of 0.01-0.1%, The mutation was not detected in other C-KIT positive patients likely due to the lack of sensitivity of the assay to detect low level alleleburden. D816V KIT mutation was not detected in any patients with venom or food anaphylaxis without LNA.
REC name
East of England - Cambridgeshire and Hertfordshire Research Ethics Committee
REC reference
17/EE/0163
Date of REC Opinion
26 Apr 2017
REC opinion
Favourable Opinion