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Test Code KITB KIT Asp816Val Mutation Analysis, Blood

Reporting Name

KIT Asp816Val Mutation Analysis, B

Useful For

Diagnosing systemic mastocytosis in blood specimens

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Specimen Type

Whole blood


Shipping Instructions


Specimen must arrive within 7 days (168 hours) of draw.



Necessary Information


The following information is required:

1. Pertinent clinical history

2. Clinical or morphologic suspicion

2. Date of collection

3. Specimen source



Specimen Required


Container/Tube:

Preferred: EDTA (lavender top)

Acceptable: ACD-B (yellow top)

Specimen Volume: 4 mL

Collection Instructions:

1. Invert several times to mix blood.

2. Send specimen in original tube.

3. Label specimen as blood.


Specimen Minimum Volume

Blood: 1 mL

Specimen Stability Information

Specimen Type Temperature Time
Whole blood Ambient (preferred) 7 days
  Refrigerated  7 days

Reference Values

An interpretive report will be provided indicating the mutation status as positive or negative.

Day(s) and Time(s) Performed

Monday through Friday

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.

CPT Code Information

81273-KIT (v-kit Hardy-Zuckerman 4 feline sarcoma viral oncogene homolog) (eg, mastocytosis), gene analysis, D816 variant(s)

LOINC Code Information

Test ID Test Order Name Order LOINC Value
KITB KIT Asp816Val Mutation Analysis, B In Process

 

Result ID Test Result Name Result LOINC Value
34851 Final Diagnosis: 34574-4

Clinical Information

Systemic mastocytosis is a hematopoietic neoplasm that can be included in the general category of chronic myeloproliferative disorders (CMPDs). These neoplasms are characterized by excessive proliferation of 1 or more myeloid lineages, with cells filling the bone marrow and populating other hematopoietic sites. In systemic mastocytosis, mast cell proliferation is the defining feature, although other myeloid lineages and B cells are frequently part of the neoplastic clone.

 

Function-altering point mutations in KIT, a gene coding for a membrane receptor tyrosine kinase, have been found in myeloid lineage cells in the majority of systemic mastocytosis cases. The most common KIT mutation is an adenine to thymine base substitution (A->T) at nucleotide position 2468, which results in an aspartic acid to valine change in the protein (Asp816Val). Much less frequently, other mutations at this same location are found and occasional cases with mutations at other locations have also been reported. Mutations at the 816 codon are believed to alter the protein such that it is in a constitutively activated state. The main downstream effect of KIT activation is cell proliferation.

 

Detection of a mutation at the 816 codon is included as one of the minor diagnostic criteria for systemic mastocytosis in the World Health Organization (WHO) classification system for hematopoietic neoplasms and is also of therapeutic relevance, as it confers resistance to imatinib, a drug commonly used to treat CMPDs. It is now clear that individual mast cell neoplasms are variable with respect to the number of cell lineages containing the mutation; some having positivity only in mast cells and others having positivity in additional myeloid and even lymphoid lineages. The mutation has not been reported in normal tissues.

Analytic Time

4 days

Reject Due To

Hemolysis

Mild OK; Gross reject

Lipemia

NA

Icterus

NA

Other

Moderately to severely clotted

NY State Approved

Yes

Method Name

Allele-Specific Oligonucleotide Polymerase Chain Reaction (PCR)

Forms

1. Hematopathology Patient Information (T676) in Special Instructions

2. If not ordering electronically, complete, print, and send a Hematopathology/Cytogenetics Test Request (T726) with the specimen.