Purpose of the test
Activating mutations in C-KIT can be detected in the bone marrow and peripheral blood, in patients with systemic mastocytosis. These mutations most commonly involve codon 816 of the intracellular tyrosine kinase domain (D816V, D816Y, D816F or D816H) and cause ligand-independent autophosphorylation of the receptor. An additional mutation in codon 560 within the juxtamembrane domain of KIT, yielding a V560G substitution has also been detected in the human mast cell leukemia line HMC-1 and in some patient with mastocytosis. It has been found that almost all sporadic adult mastocytosis patients carry codon 816 somatic mutation regardless of the classification or the prognosis of their disease. However these mutations have been found only rarely in children with progressive mastocytosis and not in familial mastocytosis.
C-KIT D816V mutations are detected using DNA allele competitive blocker and real time PCR assays with a sensitivity of 0.1%.
Bone marrow is the preferred sample for C-KIT analysis. In the absence of BM peripheral blood can be analysed but is prone to false negative results.
Presence of heparin anticoagulant will inhibit PCR applications. Clotted samples are unsuitable for DNA analysis.
Samples must be clearly labelled with the patient's first name, surname, D.O.B, hospital number and the date the sample was taken.
Storage and Transport
To be sent within 2 days and stored at room temperature.
First class postage is adequate but samples must be shipped with packaging appropriate for UN 3373 samples following packing instruction 650. See link for further details: http://www.dft.gov.uk
Samples should be addressed to:
Central Specimen Reception,
Ground Floor, Bessemer Wing,
King's College Hospital,
London SE5 9RS,
Time Limit for Extra Tests
Test specific - please enquire.
Factors affecting results or interpretation
This analysis is referred to the Leukaemia Research Group, Wessex Regional Genetics Laboratory, Salisbury District General Hospital.
Please note that mastocytosis is often focal in the marrow and absent from the peripheral blood. The analysis of peripheral blood is not ideal since it is more likely to give rise to false negative results.
Please contact the laboratory for prices (Discounts available for significant workloads)
Dr Nicholas Lea
Clinical Scientist - Haematology & Molecular Genetics
T 020 7848 5821 (020 7848 5809 for laboratory)