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Juvenile Myelomonocytic Leukemia Associated Exon Panel

Item Value
Available Stat? No
Utilization Guidelines Tests with long turn-around times (i.e., Molecular based tests and Microarrays) should only be requested on an inpatient if the result is going to affect the inpatient management. If the patient will likely be discharged before the result will be available, the test should be requested after discharge. (NOTE: UCSF Medical Center is not reimbursed for inpatient testing).

An exception to the above may be appropriate if there is a possibility the patient will not survive to be discharged and the information is important for diagnosis and/or family decisions/management (e.g., recurrence risk).
Test code JMML
Performed by Medical Genomics - Molecular Diagnostics
In House Availability Runs are usually setup bi-weekly, day shift only. Run schedule could be modified depending on sample volume.
Method Massive Parallel Next Generation DNA Sequencing
Collection Instructions Avoid hemolysis. Due to stability issues these samples should only be collected at UCSF Monday through noon Friday.

Do not collect sample in heparin. Keep sample refrigerated for overnight or longer storage.

For UCSF Samples (from remote sites) Click here for sample collection instructions

For NON-UCSF Samples Click here for Requisition form & Account set-up instructions. Note we only do institutional billing.
Container type
Lavender top (EDTA) Blood or bone marrow
Buccal swab or T25 flask Germline sample
Amount to Collect Tumor sample:
EDTA whole blood 5 mL
Bone Marrow aspirate 3 mL

Germline sample:
Cultured fibroblasts Confluent T25 flasks x2
Buccal swab 1 swab
Sample type
Tumor sample EDTA whole blood or Bone marrow aspirate

Germline sample Buccal swab or Cultured fibroblasts
Preferred volume Tumor sample:
EDTA whole blood 5 mL
Bone Marrow aspirate 3 mL

Germline sample:
Cultured fibroblasts Confluent T25 flasks x2
Buccal swab 1 swab
Min. Volume Tumor sample:
EDTA whole blood 2 mL
Bone Marrow aspirate 25 mL

Germline sample:
Cultured fibroblasts Confluent T25 flasks x2
Buccal swab 1 swab
Processing notes DO NOT FREEZE blood or bone marrow samples. Ship to CB as soon as possible.

Overnight refrigeration prior to transport is acceptable
Normal range Negative: No clinically significant variants detected.
Synonyms JMML Panel; CBL exons 8/9; KRAS exons 2/3; NRAS exons 2/3; PTPN11 exons 3/4/13
Turn around times 2-4 weeks
Additional information An interpretation of this test by a laboratory physician will be automatically performed and billed for separately.

This assay encompasses the DNA sequencing of all exons in each of the following genes: NRAS, KRAS, PTPN11, CBL, NF1, SETBP1, SH2B3, ASXL1, JAK3.
This assay is quantitative and is also intended for minimal residual disease to monitor the allele burden of one or more previously uncovered mutations in a patient. The sensitivity of detecting a somatic variant is 1-2%.

Juvenile myelomonocytic leukemia (JMML) is a rare and aggressive pediatric leukemia with poor prognosis. It is characterized by excessive proliferation of myelomonocytes that infiltrate hematopoietic and non-hematopoietic tissues.

While the suspicion of JMML is aided by clinical and hematological criteria, the additional finding of a pathogenic DNA variant previously known to be associated with JMML is often the tipping point in establishing a JMML diagnosis.

A characteristic feature of JMML is the presence of a somatic or germline mutation in RAS pathway genes such as NRAS, KRAS, PTPN11, CBL and NF1, which altogether are mutated in about 70% of JMML cases. Mutations outside the RAS pathway have been suggested to constitute secondary mutations that could also lead to the development of JMML and impact on its progression. For example, SETBP1 and JAK3 were found to constitute common targets for secondary mutations. In addition, deleterious mutations in SH2B3 have been associated with the promotion of leukemogenesis, particularly ALL, and are considered as leukemia predisposing variants. Furthermore, heterozygous somatic mutations in ASXL1 may act as tumor suppressor in myeloid malignancies such as AML and CMML, thus assisting in the differential diagnosis of JMML.

Detected variants of known clinical significance in the 9 genes will be reported. In cases when one or two genes of interest are requested, the clinically significant variants of only these genes will be reported.

Loh ML. Br J Haematol 152: 677-87, 2011
Sakaguchi et al. Nature Genetics 45:937-941, 2013
Perez-Garcia et al. Blood 122:2425-2432, 2013
Gelsi-Boyer et al. Br. J. Haem. 145:788-800, 2009

This test was developed and its performance characteristics determined by the UCSF Clinical Laboratories. It has not been cleared or approved by the Food and Drug Administration. The FDA has determined that such clearance or approval is not necessary. This test is used for clinical purposes. It should not be regarded as investigational or for research. This laboratory is certified under the Clinical Laboratory Improvement Amendments of 1988 (CLIA-88) as qualified to perform high complexity clinical laboratory testing.
CPT coding 81450
LDT or Mod FDA? Yes
Last Updated 6/22/2015 10:22:35 AM
Entry Number 1474
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