IPLab:Lab 5:Trisomy 21
ImagesEdit
This is a photomicrograph of cells obtained by amniocentesis that were stained using FISH. The cell in panel 1 was stained with markers specific for the X and Y-chromosomes. The cell in panel 2 was stained with a marker specific for chromosome 18. The cell in the center was stained with markers for chromosomes 13 and 21. Note that there are three copies of chromosome 21.
These cells, obtained by amniocentesis, were cultured and then arrested in metaphase. Nuclei from these cells were isolated and stained to demonstrate the banding pattern of each chromosome. This photograph shows a "chromosome spread." Each chromosome is identified and lined up to give a karyotype (next page).
Chromosomes from the chromosome spread are lined up to demonstrate the karyotype. In this case there are three copies of chromosome 21, just as noted in the FISH.
FISH is also useful in the diagnosis of other genetic disorders. This is an example of FISH staining on another patient using a probe specific for DiGeorge's disease. The arrow shows that there is a deletion on chromosome 22, which is diagnostic for DiGeorge's disease.
This is a karyotype of a patient with Klinefelter syndrome (47, XXY).
This is a karyotype of a patient with Turner syndrome (45, X).
Amniocentesis is a procedure in which a needle is inserted transabdominally through the uterus, into the amniotic sac, and amniotic fluid is withdrawn.