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

FCSP
80602
PF
8912
Chromosome Anomalies, Unspecified Miscellaneous with
Chromosome-Specific FISH Probes
Clinical Information: Conventional cytogenetic studies can identify the presence of chromosome
abnormalities and the presence or absence of most mosaic conditions. Conventional cytogenetic studies
utilize a variety of staining techniques to identify each chromosome. With these methods, structural or
numeric chromosome abnormalities are detected in approximately 11% of peripheral blood specimens
referred to our Cytogenetic Laboratory from patients with congenital disorders. In approximately 2% of
these chromosomally abnormal cases, the genetic makeup of the chromosome anomaly can be identified,
but not completely characterized, by conventional techniques alone. For malignant disorders, the
proportion of specimens with unresolvable chromosome abnormalities is much higher. In our experience,
the use of FISH with chromosome-specific paint probes (collections of unique DNA sequences for
specific chromosomes), locus-specific probes, and alpha-satellite probes can help establish the genetic
makeup of a high proportion of chromosome abnormalities. This includes abnormalities that cannot be
accurately characterized by conventional methods such as unusual structural alterations, questionable
mosaicism of an abnormality, and unbalanced chromosome abnormalities such as deletions, duplications,
and translocations that cannot be resolved by studies on other family members. Scoring chromosomal
aneuploidy abnormalities by FISH is generally easier than by conventional cytogenetic methods and can
be done by use of either interphase or metaphase cells. Thus, large numbers of cells can be scored to more
accurately establish the frequency of chromosome abnormalities. We recommend that conventional
chromosome analysis be performed first to establish the constitutional karyotype and determine whether
or not the patient has chromosome mosaicism.
Useful For: As an adjunct to conventional chromosome studies, to resolve unusual or complex
structural alterations, questionable mosaicism, and unbalanced chromosome abnormalities that cannot be
resolved by studies on other family members To diagnose certain disorders caused by a deletion or
duplication of a given chromosome region To identify unbalanced structural abnormalities in cases where
this information is needed more rapidly than conventional chromosome analysis can supply (eg, situations
where genetic counseling is needed quickly to decide treatment, but conventional cytogenetic studies
would require studying multiple family members) To help establish the origin and centromeric make up
of dicentric or marker chromosomes In suboptimal chromosome preparations, FISH can help confirm the
results of conventional chromosome analysis To determine whether a childâ€s deletion or duplication
detected via array comparative genomic hybridization (aCGH) is de novo or inherited
Interpretation: An interpretive report is provided.
Reference Values:
An interpretive report will be provided.
Clinical References: 1. Jalal SM, Law ME, Dewald GW: Atlas of Whole Chromosome Paint
Probes. Normal Patterns and Utility for Abnormal Cases. Rochester, MN, Mayo Foundation, 1995 2. Jalal
SM, Law ME, Christensen ER, et al: Method for sequential staining of GTL-banded metaphases with
fluorescent-labeled chromosome-specific paint probes. Am J Med Genet 1993;46:98-103 3. Kraker WJ,
Borell TJ, Schad CR, et al: Fluorescent in situ hybridization: use of whole chromosome paint probes to
identify unbalanced chromosome translocations. Mayo Clin Proc 1992;67:658-662 4. Schad CR, Kraker
WJ, Jalal SM, et al: Use of fluorescent in situ hybridization for marker chromosome identification in
congenital and neoplastic disorders. Am J Clin Pathol 1991;96:203-210
Chromosomes, Body Fluid
Clinical Information: Cytogenetic studies on body fluids (eg, pleural effusions, ascites, and
pericardial, cerebrospinal, and synovial fluids) may be helpful to diagnose or to rule-out metastases or
relapses in patients with lymphoma or other malignancies. Chromosome analysis serves as a useful
adjunct to cytology. In pleural fluids, lymphomas are often more readily diagnosed by cytogenetic
techniques than by standard cytologic examination.
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