6.1 Chromosomal Mutations Part 2 Flashcards
How many typical characteristics are possible in an individual with down syndrome?
14-16
How many typical characteristics will an individual with down syndrome typically express?
6-8
What are the most prominent phenotypes of an individual with trisomy 21?
skin fold on inner eyelid giving slanted eye
flat face
round head
physical and mental development is delayed
What are typically diseases an individual with down syndrome will experience?
respiratory disease
heart deformities
What is the region of chromosome that is important for the phenotype of Down syndrome?
down syndrome critical region
What are the two “ways” someone can exhibit down syndrome?
have the third chromosome OR have a translocation of an extra piece of chromosome 21 attached to a different chromosome
How many individuals have a mosaic of trisomy 21?
less than 2%
What does it mean to have a mosaic of trisomy 21?
some cells have three copies while other cells do not
What individuals have a higher risk of leukemia in childhood?
those with down syndrome
What do those with down syndrome have a much lower risk of?
cancers with solid tumors
What does the presence of DSCR1 do?
encodes for a protein that blocks vascular epithelial growth (VEGF) which prevents the formation of tumors
How does trisomy 21 actually occur?
nondisjunction of chromosome 21 in meiosis I results from failure of paired homologs to separate in anaphase I or II
Where does the nondisjunction of chromosome 21 typically occur?
in the ovum not the sperm
What is a NIPT?
noninvasive prenatal test that gives risk estimate of the fetus having aneuploidy
How is a NIPT conducted?
blood draw at 10 weeks gestation and then PCR amplification of the fetal DNA
