Abnormalities of chromosome number can cause spontaneous miscarriage or the birth of a baby with congenital malformations and developmental delay. This is a rapid test of the numbers of selected chromosomes in a blood sample, a sample of the placenta, CVS, amniotic fluid, or fetal blood. This test provides diagnostic and prognostic information. The standard set of tested chromosomes are 13, 18, 21, X, and Y. Other FISH probes can be added on specific requests (e.g. 22q11.2).
In Prenatal Scenario
In Postnatal Scenario
FISH is a less time-consuming technique in comparison to the conventional method of cytogenetic metaphase karyotype analysis because in the former the detection technique involves processing with either freshwater or paraffin-embedded interphase nuclei without the need of culturing. By using this technique, specific cytogenetic abnormalities, as well as a copy of aberrations numbers, can be enumerated and sketched.
For example, chromosomal microdeletion, amplification, and subsequently, translocation can easily be detected through FISH. The improved diagnostic techniques have made the treatment easier and increased the life expectancy of people. Therefore, FISH is becoming a more vital tool to detect and monitor the specific therapy with regards to the gene abnormalities.
A chorionic villus sample, amniotic fluid, or fetal blood sample are required. An invasive procedure by an obstetrician isnecessary to obtain this
2-3ml Blood Sample
In FISH, small DNA strands which have been labeled with a fluorescent probe are allowed to bind to fragments of a person’s DNA, corresponding to a particular genomic region of interest. This is useful to assess chromosome or gene copy numbers. If there has been a duplication, more of the probe will hybridize with the sample DNA and more fluorescence will be detected. If there has been a deletion in the genome, the probe cannot attach to its complementary region as it is absent and no fluorescence will be detected. This technique has been applied to serve diagnostic purposes in clinical medicine.