25546 BCR/ABL1, p190, mRNA Detection, Reverse Transcription-PCR (RT-PCR), Quantitative, Monitoring Assay, Varies (BA190)

Refrigerate specimens must arrive within 5 days (120 hours) of collection, and ambient specimens must arrive within 3 days (72 hours) of collection. Collect and package specimen as close to shipping time as possible.

Necessary Information:

The following information is required:

1. Pertinent clinical history including if the patient has a diagnosis of chronic myelogenous leukemia or other BCR/ABL1-positive neoplasm

2. Date of collection

3. Specimen source (blood or bone marrow)

mRNA transcribed from BCR/ABL (fusion of the breakpoint cluster region gene [BCR]at chromosome 22q11 to the Abelson gene [ABL] at chromosome 9q23) is detected in all chronic myelogenous leukemia (CML) patients and a subset of both acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML) patients. Although breakpoints in the BCR and ABL genes may occur in a variety of locations, splicing of the primary RNA transcripts result in only 8 fusion site variants (e1/a2, e6/a2, e13/a2, e14/a2, e19/a2, and e1/a3, e13/a3, e14/a3), which incorporate the entire sequence of the exons on both sides of the fusion site. The e1/a2 and e1/a3 fusion forms produce a 190-kDa protein designated p190. This bcr/abl protein form is found in approximately 75% of childhood ALL patients and approximately 50% of adult ALL patients, with the majority arising from e1/a2 mRNA. The p190 is also the predominant fusion form in a small subset of CML patients, although the vast majority of CML cases contain the p210 protein, typically from e13/a2 or e14/a2 mRNA fusions. Other fusion forms are very rare.

Quantitative reverse-transcription PCR (qRT-PCR) is the most sensitive method for monitoring bcr/abl levels during treatment. This test detects mRNA coding for the most common p190 fusion form (e1/a2).