FISH (Prenatal and Pregnancy Loss)
Potential Test Results:
- A normal result indicates no clinically-significant chromosome abnormalities were identified.
- 46,XX (female)
- 46,XY (male)
- An abnormal result indicates that a chromosome abnormality was identified that likely provides an explanation for the clinical indications.
- Parental testing (Postnatal Chromosome Analysis on maternal and/or paternal blood) may be recommended in order to clarify whether the result is de novo or familial for the purpose of recurrence risk calculation.
- Deletion: Missing pieces of chromosomes and/or genetic material. Some may be small and difficult to detect.
- Duplication: Extra genetic material which may be present on any chromosome, such as the presence of two horizontal bands at a specific location instead of one.
- Monosomy: The absence of one whole chromosome. This includes Turner syndrome, a female with a single X chromosome (45,X) instead of 46,XX. Most other monosomies are not compatible with life.
- Rearrangement: Genetic material is present on a chromosome but not in its usual location.
- Translocation: Translocations result when pieces of chromosomes break off and reattach to another chromosome. If it is a one-to-one switch and all of the genetic material is present (but in the wrong place), it is said to be a balanced translocation. If it is not, then it is called an unbalanced translocation.
- Trisomy: The presence of an extra chromosome; a third instead of a pair. These include Trisomy 21 (Down syndrome), Trisomy 13 (Patau syndrome), Trisomy 18 (Edwards syndrome), and Klinefelter syndrome, a male with an extra X chromosome (47,XXY) instead of 46,XY, and other less common trisomies.
- In some circumstances, a result will be unavailable.