XX/XY in Opposite Sex Bone Marrow Transplantation, FISH
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