26611 Chromosome Analysis, Hematologic Disorders, Blood (CHRHB)

​Chromosome Analysis, Peripheral Blood Unstimulated; Hematologic Chromosome Analysis; Hematologic Karyotype; Karyotype, Peripheral Blood Unstimulated​

​Assisting in the classification and follow-up of certain malignant hematological disorders when bone marrow is not available.

This test is not useful for congenital disorders. 

​Necessary Information: 

1. A reason for testing should be submitted with each specimen. Mayo labs will not reject testing if this information is not provided, but appropriate testing and interpretation may be compromised or delayed. 
2. A pathology and/or flow cytometry report may be requested by Mayo labs to optimize testing and aid in interpretation of results. 

Collection Instructions: 

1. Invert several times to mix blood.
   
2. Send whole blood specimen in original tube. Do not aliquot. 
   

All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.

​Interfering factors:

Technical:
-Cell lysis caused by forcing blood quickly through the needle at collection
-Use of an improper anticoagulant or improperly mixing the blood with the anticoagulant
-Clotted blood specimen
-Excessive transport time
-Exposure of the specimen to extreme temperature

Biological:
-Abnormalities missed due to sampling error
-Subtle structural chromosome abnormalities may not be detected by conventional chromosome analysis
-Neoplastic cells not dividing or not circulating in the bloodstream

​Chromosomal abnormalities play a central role in the pathogenesis, diagnosis, and monitoring of treatment of many hematologic disorders. Whenever possible, it is best to do chromosome studies for neoplastic hematologic disorders on bone marrow. Bone marrow studies are more sensitive and the chances of finding metaphases are about 95%, compared with only a 60% chance for blood studies. When it is not possible to collect bone marrow, chromosome studies on blood may be useful.

When blood cells are cultured in a medium without mitogens, the observation of any chromosomally abnormal clone may be consistent with a neoplastic process.

Conventional chromosome studies of B-cell disorders are not always successful because B lymphocytes do not proliferate well in cell culture. The agent CpG 7909 (CpG) is a synthetic oligodeoxynucleotide that binds to the Toll-like receptor 9 (TLR9) present on B cells, causing B-cell activation. In the laboratory setting, CpG may be used as a mitogen to stimulate B cells in patient specimens, thus allowing identification of chromosome abnormalities. CpG stimulation reveals an abnormal karyotype in approximately 80% of patients with of chronic lymphocytic leukemia, and the karyotype is complex in 20% to 25% of cases. Several studies have reported that increased genetic complexity revealed by CpG-stimulated chromosome studies confers a less favorable time to first treatment, treatment response, and overall survival.

​The presence of an abnormal clone usually indicates a malignant neoplastic process.

The absence of an apparent abnormal clone in blood may result from a lack of circulating abnormal cells and not from an absence of disease.

On rare occasions, the presence of an abnormality may be associated with a congenital abnormality and thus, not related to a malignant process. When this situation is suspected, consultation with a Clinical Geneticist is recommended.​