Final Review Flashcards
Autosomal dominant:
carrier rate
disease frequency
gene frequency
carrier rate: null
disease frequency = frequency of heterozygotes
gene frequency = 1/2 * frequency of heterozygotes
Autosomal recessive:
carrier rate
disease frequency
gene frequency
X-linked:
carrier rate
disease frequency
gene frequency
What are the three common trisomies?
13
18
21
[in other words, trisomies of these three chromosomes are still viable]
Which cytogenetic techniques can and cannot detect balanced rearrangements?
can detect: karyotyping
cannot detect: FISH + CMA
What is an advantage of CMA over FISH?
CMA is a whole genome scan, whereas FISH is targeted and requires a probe (you would need antecedent testing to know which probe to use)
Apart from relative speed, differentiate between interphase and metaphase FISH.
interphase FISH does not give location, but metaphase FISH does
What are the five acrocentric chromosomes?
13, 14, 15, 21, 22
What is the relationship between a mother with an isochromosome 21 and the risk of her children having Down syndrome?
a mother with isochromosome 21 would have a 100% chance of having a child with Down syndrome
What is the cutoff age for “advanced maternal age?”
35
What is the relationship between uniparental disomy and similarity between two chromosomes in a given individual?
uniparental disomy is typically only for one chromosome — if you have a patient with multiple chromosomes that have overlap, then you’re probably dealing with a common ancestor/consanguinity scenario
Differentiate between absence of heterozygosity and loss of heterozygosity.
absence of heterozygosity: inherited due to something like consanguinity, NOT visible on CMA
loss of heterozygosity: loss of functional copy due to mutation, IS visible on CMA
Write out the formula for the odds ratio.
