Mayo Test Catalog, (Sorted By Test Name) - Mayo Medical ...

CPG
89090
Useful For: Prenatal diagnosis of chromosome abnormalities (trisomies, deletions, translocations, etc)
at about 9 to 12 weeks of gestation
Interpretation: Cytogenetic studies on chorionic villus sampling (CVS) are considered more than 99%
reliable for the detection of most fetal chromosome abnormalities. However, subtle or cryptic
abnormalities involving microdeletions usually can be detected only with the use of targeted FISH testing.
Approximately 3% of chorionic villi specimens analyzed are found to have chromosome abnormalities.
Some of these chromosome abnormalities are balanced and may not be associated with birth defects. A
normal karyotype does not rule out the possibility of birth defects, such as those caused by
submicroscopic cytogenetic abnormalities, molecular mutations, and environmental factors (ie, teratogen
exposure). For these reasons, clinicians should inform their patients of the technical limitations of
chromosome analysis before the procedure is performed, so that patients may make an informed decision
about pursuing the procedure. It is recommended that a qualified professional in Medical Genetics
communicate all results to the patient.
Reference Values:
46,XX or 46,XY. No apparent chromosome abnormality.
An interpretive report will be provided.
Clinical References: Van Dyke DL, Roberson JR, Wiktor A: Prenatal cytogenetic diagnosis. In KD
McClatchey's Clinical Laboratory Medicine. 2nd Edition. Philadelphia, Lippincott, Williams, & Wilkins,
2002, Chapter 31, pp 636-657
Chromosome Analysis, CpG Mitogen Study for B-Cell Disorder
Clinical Information: Conventional chromosome studies of B-cell disorders are not always
successful because B-cell lymphocytes do not proliferate well in cell culture. FISH is an informative
method to detect common B-cell-associated chromosome abnormalities, but FISH-based assays do not
detect all abnormalities. 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. Different disorders have differing levels of response to CpG. In 1 study,
B-cell chronic lymphocytic leukemia (CLL) and marginal zone lymphoma showed the strongest response,
followed by small lymphocytic lymphoma, follicular lymphoma, mantle cell lymphoma, and large cell
lymphoma. It is likely that CpG-stimulated chromosome analysis and FISH will be complementary tests.
For example, about half of the 13q deletions seen in CLL and some lymphomas are microdeletions that
are detectable by FISH, but not by conventional metaphase analysis. CpG-stimulation reveals an abnormal
karyotype in approximately 80% of patients with B-cell CLL, 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.
Useful For: Identifying chromosome abnormalities associated with B-cell disorders
Interpretation: The abnormalities detected, as well as their known prognostic significance, will be
provided in an interpretive report. 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. On rare occasions, the presence of an abnormality may be associated with a
congenital abnormality and, thus, would not be related to the malignant process. Follow-up with a medical
genetics consultation is recommended.
Reference Values:
46,XX or 46,XY. No apparent chromosome abnormality.
An interpretive report will be provided.
Clinical References: 1. Mayr C, Speicher MR, Kofler DM, et al: Chromosomal translocations are
associated with poor prognosis in chronic lymphocytic leukemia. Blood 2006 Jan 15;107(2):742-751 2.
Stockero KJ, Fink SR, Smoley SA, et al: Metaphase cells with normal G-bands have cryptic interstitial
deletions in 13q14 detectable by fluorescence in situ hybridization in B-cell chronic lymphocytic
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