Ambiguous Genitalia FISH For Prenatal Aneusomy Trisomy 13 (Patau Syndrome) Trisomy 18 (Edwards Syndrome) Trisomy 21 (Down Syndrome) Turner Syndrome, FISH XXY, XXX, or XYY Prenatal aneuploidy
Amnio Aneuploidy FISH SO (PADF)
Prenatal Aneuploidy Detection, FISH
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 for 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.
Provide a reason for referral and gestational age with each specimen, and verify the specimen source. The laboratory will not reject testing if this information is not provided, but appropriate testing and interpretation may be compromised or delayed.
All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.
The use of these probes has been approved by the Food and Drug Administration as a stand-alone test. However, we recommend that complete chromosome analysis (CHRAF / Chromosome Analysis, Amniotic Fluid or CHRCV / Chromosome Analysis, Chorionic Villus Sampling) or chromosomal microarray (CMAP / Chromosomal Microarray, Prenatal, Amniotic Fluid/Chorionic Villus Sampling) be performed in conjunction with this FISH test. In cases where the FISH analysis is normal, a chromosome analysis or chromosomal microarray allows for the potential identification of more complex abnormalities and the less common numeric abnormalities of other chromosomes. In cases where the FISH study is abnormal, chromosome analysis can determine whether the abnormality is due to aneuploidy or a complex structural abnormality, allowing for recurrence risk information for the family.
-Inadequate amount of specimen may not permit adequate analysis
-Exposure of the specimen to temperature extremes (freezing or greater than 30 degrees C) may kill cells and interfere with attempts to culture cells
-Improper packaging may result in broken, leaky, and contaminated specimens during transport
-Transport time should not exceed 2 days
-Contamination by maternal cells may interfere with attempts to culture cells and may cause interpretive problems
Approximately half of clinically recognizable spontaneous abortions have a major chromosomal anomaly.
Up to 95% of chromosomal abnormalities diagnosed prenatally involve aneuploidy (gain or loss of whole chromosome) of chromosomes 13, 18, 21, X, and Y.
In liveborn infants, about 8/1,000 have a major chromosome anomaly, of which 6.5/1,000 involve aneuploidy of the 5 chromosomes analyzed by this test. Therefore, aneuploidy of chromosomes 13, 18, 21, X, and Y accounts for 81% to 95% of major chromosome anomalies in liveborn infants.
Techniques to detect aneuploidy include standard chromosome analysis and FISH. Standard chromosome analysis from amniotic fluid cells or chorionic villi requires 5 to 9 days for culture, harvest, and analysis. FISH, which uses DNA probes and can be performed on cultured and uncultured cells, can rapidly detect aneuploidy of 13, 18, 21, X, and Y in uncultured amniotic fluid cells or chorionic villi. FISH-based analysis may be helpful in medically urgent evaluations of newborn infants suspected to have aneuploidy of any of these chromosomes.
This test does not detect aneuploidy of chromosomes other than 13, 18, 21, X, or Y. This test does not detect other chromosomal or structural anomalies.
Low levels of mosaicism involving chromosomes 13, 18, 21, X, or Y may not be detected by this procedure.