Mobile Site ›
Print Friendly View

Test ID: FBALL    
B-Cell Acute Lymphoblastic Leukemia (ALL), FISH

‹ Back to Pediatric index

Available on the App Store

Useful For Suggests clinical disorders or settings where the test may be helpful

Detecting a neoplastic clone associated with the common chromosome anomalies seen in patients with B-cell acute lymphoblastic leukemia (B-ALL)

 

Identifying and tracking known chromosome abnormalities in patients with B-ALL and tracking response to therapy

 

As an adjunct to conventional chromosome studies in patients with B-ALL

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

In the United States, the incidence of acute lymphoblastic leukemia (ALL) is roughly 6,000 new cases per year (as of 2009), or approximately 1 in 50,000. ALL accounts for approximately 70% of all childhood leukemia cases (ages 0 to 19 years), making it the most common type of childhood cancer. Approximately 85% of pediatric cases of ALL are B-cell lineage (B-ALL) and 15% are T-cell lineage (T-ALL). It has a peak incidence at 2 to 5 years of age. The incidence decreases with increasing age, before increasing again at around 50 years of age. ALL is slightly more common in males than females. There is an increased incidence of ALL in individuals with Down Syndrome, Fanconi anemia, Bloom syndrome, ataxia telangiectasia, X-linked agammaglobulinemia, and severe combined immunodeficiency. The overall cure rate for ALL in children is about 90% and about 45% to 60% of adults have long-term disease-free survival. CRLF2/IGH rearrangements are more commonly observed in patients with Down Syndrome or of Hispanic decent.

 

Specific genetic abnormalities are identified in the majority of cases of B-ALL, either by conventional chromosome studies or fluorescence in situ hybridization (FISH) studies. Each of the genetic subgroups are important to detect and can be critical prognostic markers. The decision for early transplantation may be made if t(9;22)(q34;q11.2), MLL translocations, RUNX1 duplication/amplification or a hypodiploid clone is identified. In contrast, if ETV6/RUNX1 fusion is detected by FISH or hyperdiploidy is identified by chromosome studies, the patient has a favorable prognosis and transplantation is rarely considered.

 

A combination of cytogenetic and FISH testing is currently recommended in all pediatric and adult patients to characterize the B-ALL clone for the important prognostic genetic subgroups. A summary of the characteristic chromosome abnormalities identified in B-ALL is listed in the following Table.

 

Common Chromosome Anomalies in B-cell Acute Lymphoblastic Leukemia

Cytogenetic change

Typical demographic

Risk category

t(12;21)(p13;q22), ETV6(TEL)/RUNX1(AML1)

Pediatric

Favorable

Hyperdiploidy

Pediatric

Favorable

t(1;19)(q23;p13.3), PBX1/TCF3

Pediatric

Intermediate

t(9;22)(q11.2;q34), BCR/ABL1

Pediatric/Adult

Unfavorable

iAMP21, RUNX1

Pediatric

Unfavorable

del(9p), CDKN2A(p16)

All ages

Variable

t(11q23;var), MLL

All ages

Unfavorable

t(4;11)(q21;q23), AFF1(AF4)/MLL

All ages

Unfavorable

t(9;11)(p22;q23), MLLT3(AF9)/MLL

All ages

Unfavorable

t(11;19)(q23;p13.1), MLL/ELL

All ages

Unfavorable

t(11;19)(q23;p13.3), MLL/MLLT1(ENL)

All ages

Unfavorable

t(14q32;var), IGH

All ages

Variable

t(X;14)(p22;q32)/t(Y;14)(p11;q32), CRLF2/IGH

Adolescent/Young Adult

Unfavorable

del(17p), TP53

All ages

Unfavorable

Complex karyotype (> or =4abnormalities)

Adult

Unfavorable

Low hypodiploidy/near triploidy

Adult

Unfavorable

Near-haploid/hypodiploid

All ages

Unfavorable

 

 

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

An interpretive report will be provided.

Interpretation Provides information to assist in interpretation of the test results

A neoplastic clone is detected when the percent of cells with an abnormality exceeds the normal reference range for any given probe.

 

The absence of an abnormal clone does not rule out the presence of a neoplastic disorder.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

This test is not FDA approved and it is best used as an adjunct to existing clinical and pathologic information.

 

FISH is not a substitute for conventional chromosome studies because the latter detects many chromosome anomalies associated with other hematological disorders that would be missed by this FISH panel test.

 

Bone marrow is the preferred specimen type for this FISH test. If bone marrow is not available, a blood specimen may be used if there are malignant cells in the blood specimen (as verified by hematopathology).

Supportive Data

Each probe was independently tested and verified on unstimulated peripheral blood and bone marrow specimens. Normal cutoffs were calculated based on the results of 25 normal specimens. For each probe set a series of chromosomally abnormal specimens was evaluated to confirm each probe set detected the anomaly it was designed to detect.

Clinical Reference Provides recommendations for further in-depth reading of a clinical nature

1. Dewald GW, Ketterling RP: Conventional cytogenetics and molecular cytogenetics in hematological malignancies. In Hematology. Basic Principles and Practice. Fourth edition. Edited by R Hoffman, E Benz, S Shattil, et al. Philadelphia, Churchill Livingston, 2005, pp 928-939

2. Pui CH, Relling MV, Downing JR: Acute lymphoblastic leukemia. N Engl J Med 2004 Apr;350(15):1535-1548

3. Swerdlow SH, Campo E, Harris NL, et al: WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues. Fourth edition. Lyon, France, IARC Press, 2008, 168-175

4. Moorman AV, Harrison CJ, Buck GA, et al: Karyotype is an independent prognostic factor in adult acute lymphoblastic leukemia (ALL): analysis of cytogenetic data from patients treated on the Medical Research Council (MRC) UKALLXII/Eastern Cooperative Oncology Group (ECOG) 2993 trial. Blood 2007 Apr 15;109(8):3189-3197

5. Moorman, AV: The clinical relevance of chromosomal and genetic abnormalities in B-cell precursor acute lymphoblastic leukemia. Blood Rev 2012;26:123-135

Special Instructions and Forms Describes specimen collection and preparation information, test algorithms, and other information pertinent to test. Also includes pertinent information and consent forms to be used when requesting a particular test