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Interpretive Handbook

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Test 84387:
Myelodysplastic Syndrome (MDS), FISH

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

Myelodysplastic syndromes (MDS) primarily occur in the older adult population and have a yearly incidence of 30 in 100,000 in persons greater than 70 years of age. These disorders are typically associated with a hypercellular bone marrow and low peripheral blood counts, and with significant morbidity and mortality. The eventual clinical outcome for patients with MDS relates to either bone marrow failure or transformation to acute myeloid leukemia. MDS can be either primary (de novo) or secondary (due to previous treatment with alkylating or etoposide chemotherapy, with or without radiation).

 

Cytogenetic studies can provide confirmatory evidence of clonality in MDS and can be used to provide clinical prognostic or diagnostic information. Clonal cytogenetic abnormalities are more frequently observed in cases of secondary MDS (80% of patients) than in primary MDS (40%-60% of patients). The common chromosomal abnormalities associated with MDS include: inv(3), -5/5q-, -7/7q-, +8, 13q-, and 20q-. These abnormalities can be observed singly or in concert. In addition, MLL rearrangements, t(1;3) and t(3;21) are more frequently associated with secondary MDS.

 

Conventional chromosome analysis is the gold standard for identification of the common, recurrent chromosome abnormalities in MDS. However, this analysis requires dividing cells, takes 5 to 7 days to process, and some of the subtle rearrangements can be missed (eg, MLL abnormalities). Thus, we have validated a combination of commercially available and Mayo Clinic in-house developed FISH probes to detect the common chromosome abnormalities observed in MDS patients. These probes have diagnostic and prognostic relevance.  

 

Our panel of multiple FISH probes can be utilized to study nonproliferating (interphase) cells and can identify the common cytogenetic abnormalities associated with MDS.

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 myelodysplastic syndromes or other myeloid malignancies

 

Evaluating specimens in which standard cytogenetic analysis is unsuccessful

 

Identifying and tracking known chromosome anomalies in patients with myeloid malignancies and tracking response to therapy

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 approved by the FDA and it is best used as an adjunct to existing clinical and pathologic information.

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.

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

1. Bernasconi P, Klersy C, Boni M, et al: World Health Organization classification in combination with cytogenetic markers improves the prognostic stratification of patients with de novo primary myelodysplastic syndromes. Br J Haematol 2007 May;137(3):193-205

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