Chromosomal Abnormalities Flashcards
The normal cell has how many chromosomes?
46 chromosomes or 2 pairs of 23
A condition in which there are an abnormal number of whole chromosomes
Aneuploidy
having 69 chromosomes/ 3 sets
Triploidy
A situation where some cells have an abnormal number of chromosomes while other cells do not.
Mosaic
Cell has the normal pair of each chromosome—46 chromosomes
Diploid
Cell has only one of an individual chromosome
Haploid
The most common cause of abnormal serum screening test
Incorrect dating of the pregnancy
Analysis of fetal chromosomes
Fetal karyotyping
3 main procedures for fetal karyotyping
- Chorionic Villi sampling(CVS)
- amniocentesis
- cordocentesis
Earliest procedure that can be performed during pregnancy for fetal karyotyping
CVS
CVS is performed between:
10-13 weeks
Amniocentesis is performed between:
15-20 weeks
Cordocentesis aka
Percutaneous umbilical cord sampling
Cordocentesis is performed:
After 17 weeks
Most common chromosomal abnormality
Trisomy 21