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89338
to summarize here. The reader is referred to the Mitelman Database of Chromosome Aberrations in
Cancer (2001). Edited by F Mitelman, B Johansson, F Mertens.Available at
http://cgap.nci.nih.gov/Chromosomes/Mitelman
Useful For: Assisting in the classification of malignant tumors associated with chromosomal
abnormalities
Interpretation: The observation of a chromosomally abnormal clone is evidence of a clonal neoplastic
process. Certain chromosome abnormalities may also be specifically associated with certain morphologic
classifications. In many tumors, the cytogenetic interpretation may be complicated by the observation of
numerous complex chromosome anomalies. Nevertheless, the presence of certain chromosome
abnormalities within a complex karyotype may still aid in classifying the tumor. However, a normal
karyotype does not eliminate the possibility of a neoplastic process. Additionally, FISH testing or other
strategies may be more appropriate for certain tumor types. On rare occasions, the presence of an
abnormality may be associated with a congenital abnormality that is not related to a malignant neoplastic
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: Sandberg AA, Turc-Carel C, Gemmell RM: Chromosomes in solid tumors and
beyond. Cancer Res 1988;48:1049-1059
Chromosome Analysis, Spontaneous Breakage Analysis, Blood
Clinical Information: Chromosomal instability syndromes are autosomal recessive disorders
characterized by defects in DNA repair mechanisms or genetic instability. Patients with these disorders
have an increased risk of developing malignant disorders. When blood from affected individuals is
cultured and chromosome analysis is performed, elevated rates of chromosomal rearrangements are
observed. These disorders include ataxia telangiectasia (AT) and Nijmegen breakage syndrome (NBS).
An increased frequency of chromosome rearrangements, including involvement at 7p13, 7q34, 14q11.2,
or 14q32, signals a positive result. NBS usually has a higher frequency of cells with chromosome
rearrangements than AT and generally does not include the clinical features of ataxia or increased serum
alpha-fetoprotein.
Useful For: Evaluating patients with possible chromosome instability syndromes including ataxia
telangiectasia and Nijmegen breakage syndrome
Interpretation: The pattern of chromosome breakage and the number of breaks are compared to a
normal control and an interpretive report is provided.
Reference Values:
An interpretive report will be provided.
Clinical References: 1. Gatti R: Ataxia-Telangiectasia. Available from URL:
http://www.ncbi.nlm.nih.gov/books/NBK26468/accessed on February 16, 2012 2. Concanon P, Gatti R:
Nijmegen Breakage Syndrome. Available from URL:
http://www.ncbi.nlm.nih.gov/books/nbk1176/accessed on February 16, 2012 3. Dewald GW , Noonan KJ,
Spurbeck JL, Johnson DD: T-lymphocytes with 7;14 translocations: frequency of occurrence, breakpoints,
and clinical and biological significance. Am J Hum Genet 1986 Apr;38(4):520-532 4. Digweed M,
Sperling K: Nijmegen breakage syndrome: clinical manifestation of defective response to DNA
double-strand breaks. DNA Repair 2004;3:1207-1217 5. Howell RT, Chromosome instability syndromes.
Chp 9, p 227-254 in DE Rooney's Human Cytogenetics: Malignancy and Acquired Abnormalities. Oxford
University Press, 2001 6. Ray JH & German J. The chromosome breakage syndromes: clinical features,
cytogenetics, and molecular genetics, in McClatchey's Clin Lab Med, 2002
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