Test ID: FBMT
XX/XY in Opposite Sex Bone Marrow Transplantation, FISH
Secondary ID 
A test code used for billing and in test definitions created prior to November 2011
NY State Approved Indicates the status of NY State approval and if the test is orderable for NY State clients.
Useful For Suggests clinical disorders or settings where the test may be helpful
Evaluating engraftment success by determining the proportion of donor and recipient interphase cells present in opposite sex bone marrow transplant recipients
Monitoring the proportion of host and recipient cells over time may be useful to identify significant clinical changes
Method Name A short description of the method used to perform the test
Fluorescence In Situ Hybridization (FISH)
Reporting Name A shorter/abbreviated version of the Published Name for a test; an abbreviated test name
Aliases Lists additional common names for a test, as an aid in searching
FISH (Fluorescent In Situ Hybridization)
FISH, Opposite Sex BM Transplant
Fluorescent In Situ Hybridization for Opposite Sex Bone Marrow Transplant
Opposite Sex Bone Marrow Transplantation
Specimen Type Describes the specimen type needed for testing
Specimen Required Defines the optimal specimen. This field describes the type of specimen required to perform the test and the preferred volume to complete testing. The volume allows automated processing, fastest throughput and, when indicated, repeat or reflex testing.
Provide a reason for referral with each specimen. The laboratory will not reject testing if this information is not provided, but appropriate testing and interpretation may be compromised or delayed.
Forms: If not ordering electronically, submit a Cytogenetics Hematologic Disorders Request Form (Supply T607) with the specimen.
Advise Express Mail or equivalent if not on courier service.
Submit only 1 of the following specimens:
Specimen Type: Blood
Container/Tube: Green top (sodium heparin)
Specimen Volume: 7-10 mL
Collection Instructions:
1. Invert several times to mix blood.
2. Other anticoagulants are not recommended and are harmful to the viability of the cells.
Specimen Type: Bone marrow
Container/Tube: Green top (sodium heparin)
Specimen Volume: 1-2 mL
Collection Instructions:
1. Invert several times to mix bone marrow.
2. Other anticoagulants are not recommended and are harmful to the viability of the cells.
Specimen Minimum Volume Defines the amount of specimen required to perform an assay once, including instrument and container dead space. Submitting the minimum specimen volume makes it impossible to repeat the test or perform confirmatory or perform reflex testing. In some situations, a minimum specimen volume may result in a QNS (quantity not sufficient) result, requiring a second specimen to be collected.
Reject Due To Identifies specimen types and conditions that may cause the specimen to be rejected
| Hemolysis | NA |
| Lipemia | NA |
| Icterus | NA |
| Other | Clotted blood or bone marrow |
Specimen Stability Information Provides a description of the temperatures required to transport a specimen to the laboratory. Alternate acceptable temperature(s) are also included.
| Specimen Type | Temperature | Time |
|---|---|---|
| Varies | Ambient (preferred) | |
| Refrigerated | ||
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Bone marrow transplantation (BMT) is an important treatment for patients with certain malignant hematologic disorders and hereditary conditions.
Conventional cytogenetic studies can identify chromosome abnormalities, establish the proportion of donor and recipient metaphase cells to monitor the success of BMT engraftment, and detect residual disease after treatment. However, conventional chromosome studies are usually done on only 20 to 30 metaphase cells and may be less sensitive than other methods.
When the donor and recipient are of opposite sex, the donor and recipient cells can be readily identified by their sex chromosome complement. FISH using probes for the X and Y chromosomes can be used to estimate the proportion of donor and recipient interphase cells in bone marrow or peripheral blood. Monitoring the proportion of host and recipient cells over time also may be useful to identify significant clinical changes.
This method is easy, objective, and permits analysis of large numbers of cells. Our experience also suggests that FISH is economical, rapid, and accurate.(1) FISH specimens are preprocessed in the same manner as chromosome analysis specimens. If FISH results or clinical circumstances suggest the possibility of disease relapse, chromosome studies can be performed on the same specimen to determine if an abnormal clone is present.
To maximize the cost-effectiveness of FISH and chromosome analysis, we recommend conventional chromosome analysis prior to BMT to establish the karyotype of the malignant cell line. After BMT, the use of FISH alone on either bone marrow or peripheral blood may be sufficient to monitor the success of the engraftment.
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.
< or =0.3% cells with XY signals for pretransplant females
< or =0.6% cells with XX signals for pretransplant males
Interpretation Provides information to assist in interpretation of the test results
Specimens from females that have >0.6% XX interphase cells have residual XX host cells.
Specimens from males that have >0.3% XY interphase cells have residual XY host cells.
The results of both conventional chromosome studies and FISH are best interpreted when findings before and after bone marrow transplantation are compared. Our reports include a summary of the percentage of host and donor cells present in prior studies from the same patient.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
This test is designed for opposite sex bone marrow transplants (BMTs) only; results are not useful for same sex bone marrow transplants.
Examination of the sex chromosome complement of interphase cells using FISH does not distinguish between malignant and normal cells. We strongly recommend using both FISH and cytogenetic studies to monitor patients.
A single X chromosome is sometimes lost in bone marrow cells of females, and the Y chromosome is sometimes lost in bone marrow cells of males, regardless of whether the specimen is from the donor, recipient, or a post-BMT patient.
Rare males may have an unusual Y chromosome that cannot be identified with these probes, but this finding should be readily apparent by analysis of metaphase cells using FISH.
Occasional patients may have chromosome polymorphisms that may hybridize with the Y probe, but this should be readily apparent by analysis of metaphase cells using FISH.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
Dewald GW, Schad CR, Christensen ER, et al: Fluorescence in situ hybridization with X and Y chromosome probes for cytogenetic studies on bone marrow cells after opposite sex transplantation. Bone Marrow Transplant 1993;12:149-154
Method Description Describes how the test is performed and provides a method-specific reference
FISH is performed using directly labeled, multicolored fluorescent DNA probes specific for the X chromosome centromere and the distal portion of the Y chromosome long-arm. FISH is performed by placing the probes on microscope slides with the cells from the specimen to be studied. The DNA of the probes and cells are denatured at 70 degrees C for 2 minutes. The probe and chromosomal DNA are then allowed to hybridize overnight at 37 degrees C. The cells are washed with post-hybridization solution to remove excess probe DNA and hybridization solution. With this method, XX cells have 2 orange (X chromosome) signals and XY cells have a single orange (X chromosome) and a single green (Y chromosome) signal. The FISH studies involve analysis of 500 interphase cells and up to 5 metaphase cells. The number of donor and recipient cells is expressed as a percentage of the total number of interphase cells analyzed. Greater than 0.6% XX cells in a female recipient or >0.3% XY cells in a male recipient are regarded as evidence for the presence of residual recipient cells. (Dewald GW, Schad CR, Christensen ER, et al: Fluorescence in situ hybridization with X and Y chromosome probes for cytogenetic studies on bone marrow cells after opposite sex transplantation. Bone Marrow Transplant 1993;12:149-154)
Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.
Samples processed Monday through Sunday. Results reported Monday through Friday, 8 a.m.-5 p.m. CST.
Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.
Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Medical Laboratories until the release of the test result
Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location The location of the laboratory that performs the test
Test Classification Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer's instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR), Investigation Use Only (IUO) product, or a Research Use Only (RUO) product.
CPT Code Information Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Medical Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
88271 x 2-DNA probe, each
88275 x 2-Interphase in situ hybridization
88291-Interpretation and report
LOINC® Code Information Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the result codes returned for this test or profile.
| Result ID | Reporting Name | LOINC Code |
|---|---|---|
| 16209 | Specimen | 31208-2 |
| 16341 | Specimen ID | N/A |
| G_691 | Source | N/A |
| 16210 | Order Date | N/A |
| G_694 | Reason For Referral | 42349-1 |
| 16211 | Method | In Process |
| 16213 | Results | In Process |
| 16214 | Interpretation | 69965-2 |
| 16215 | Amendment | In Process |
| 16216 | Consultant | N/A |
| 16217 | Report Date | N/A |
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