Genetic Testing Flashcards
aneuploidy
entire missing or extra chromosome
ex: trisomy
trisomy 21
down syndrome
What genetic tests detect aneuploidy?
karyotype and FISH testing
microdeletion / microduplication
extra or missing chromosome regions of varying size
ex: DiGeorge
What tests can you use to detect microdeletion / microduplication?
microarray (possibly FISH)
What tests detect translocations and inversions?
karyotype or FISH
Balance translocation / inversions
reciprocal exchange (nothing lost or gaineed)
usually not pathogenic
Unbalanced translocation / inversions
typically pathogenic
Lynch syndrome is an example of …
single gene mutation
What is a common example of epigenetics?
Prader-Willi Angelman syndrome
What tests work for epigenetics?
methylation testing
karyotype
looks at big picture of chromosomes
large structural differences
What indicates karyotype testing?
Fhx of trisomy
ambiguous genitalia
multiple miscarriages
When do you do karyotype testing?
during the prenatal period
FISH testing
fluorescent probe tests for specific DNA sequences
SNP microarray
can detect small missing or extra pieces of chromosomes
Limitation of SNP microarray
cannot detect single gene variation
cannot detect large structural rearrangements
When do you use SNP microarray?
during the prenatal period
Panel testing
can test several genes at once
When do you do a genetic panel?
condition with possible known genetic mutations, similar phenotypes
When do you use whole exome / genome testing?
when other tests were negative
Limitation of whole genome testing?
doesn’t sequence introns + mitochondrial DNA
can’t detect large structural rearrangements
Methylation disadvantage
gives no information about the genetic code
Cell-free DNA
looks for DNA in blood
just a SCREENING, need to send more tests after
What can cell-free DNA be used for?
prenatal screening
somatic tumor
