Test Catalog

Test ID: BMTF    
XX/XY in Opposite Sex Bone Marrow Transplantation, FISH

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

Testing Algorithm Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

This test only includes a charge for professional interpretation of results and does not include charges for probe application or analysis.


This test includes a charge for application of the first probe set (2 FISH probes) and professional interpretation of results. Additional charges will be incurred all reflex probes performed. Analysis charges will be incurred based on the number of cells analyzed per probe set. If no cells are available for analysis, no analysis charges will be incurred.

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

Bone marrow transplantation (BMT) continues to be an important treatment for patients with malignant hematologic disorders and bone marrow failure syndromes. Conventional cytogenetic studies can be performed to evaluate a mixture of donor and recipient cells in opposite sex bone marrow transplants at a sensitivity of approximately 5%. Interphase FISH testing for X and Y chromosomes in opposite sex bone marrow transplant specimens results in an improved sensitivity of approximately 0.5%.

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

Residual XX host cells are present in female BMT recipients when the percent of XX interphase cells exceeds the cutoff (>0.6%XX).


Residual XY host cells are present in male BMT recipients when the percent of XY interphase cells exceeds the cutoff (>0.3%XY).

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.

Supportive Data

A blinded study using the DXZ1/DYZ1 probe set was performed on a series of patients who had undergone opposite sex bone marrow transplant. Normal cutoff were calculated based on the results of testing 25 male and 25 female normal donor samples.

Clinical Reference Recommendations for 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