PGD Flashcards
ASRM Course
An unknown embryo biopsy sample is labeled in one fluorochrome while a known normal euploid control is labeled with another fluorochrome. The two are allowed to hybridize to a slide that has segments of bacterial artificial chromosomes. The slide is read in a specialized instrument and analysis is performed via computer software.
This technique is called:
a. Fluorescent in situ hybridization (FISH)
b. Comparative genomic hybridization (CGH)
c. Array comparative genomic hybridization (aCGH)
d. Next gen sequencing
c-
A patient comes to your clinic requesting preimplantation genetic screening (PGS) because she is afraid of a multiple pregnancy and would like a single embryo transferred. You tell her:
a. PGS may be effective as a method to allow single embryo transfer without reducing the pregnancy rate, but this has only been demonstrated in one randomized clinical trial.
b. She should have 2 embryos transferred after PGS for the highest pregnancy rate and she can always have multifetal reduction if she has a multiple pregnancy.
c. She should have 2 embryos transferred without PGS for the highest pregnancy rate since it is rare for more than one untested embryo to implant.
d. It is a risky approach that may reduce her chances of pregnancy since there have not been any studies investigating a single embryo transfer with PGS.
a.
FISH (fluorescent in situ hybridization) was widely used for PGS analysis but no longer appears to have widespread use. One disadvantage of FISH is:
a. The need to perform a whole genome amplification step before hybridization.
b. The disadvantages are outweighed by several randomized trials that should show improvement in pregnancy rates.
c. FISH is prone to instances of allele dropout (ADO).
d. FISH is limited to the number of fluorochromes that can be used at once.
d.
Detection of the incidence of allele dropout has increased due to:
a. Labeling the maternal and paternal chromosomes with fluorochromes
b. The use of informative polymorphic markers to detect both maternal and paternal allele
c. Trophectoderm biopsy
d. Allele dropout is no longer a concern as improved methods have eliminated the incidence.
d.
A patient and her husband carry the same mutation for cystic fibrosis. You perform embryo biopsy and the preimplantation genetic diagnosis (PGD) report indicates that only one affected allele was detected and there was no answer for the second allele. The embryo is a good quality blastocyst and is the best quality embryo she has. Is it safe to transfer this embryo?
a. Yes, it is a good quality blastocyst so the odds are great that this is a normal euploid embryo.
b. Yes, the worst case scenario would be that the embryo is a carrier (one normal plus one affected allele just like the parents are)
c. No, you do not know the status of the other allele; since this allele is affected, the other allele also has a high probability of being affected.
d. No, you don’t know the status of the other allele. You could offer to rebiopsy and have a sample reanalyzed to try to determine if the other allele may be normal.
d.
- When performing PGS for chromosome analysis, whole genome amplification (WGA) is not used for which of the following techniques?
a. Array comparative genomic hybridization
b. Single nucleotide polymorphism (SNP) arrays
c. Real-time polymerase chain reaction (qPCR)
d. Comparative genomic hybridization (CGH)
d.
The 3 basic steps of the polymerase chain reaction are:
a. Fixation, denaturation, hybridization
b. Denaturation, annealing, extension
c. Extraction, denaturation, fixation
d. Denaturation, hybridization, annealing
b.
A patient asks you about the accuracy of PGS testing. You should inform her that:
a. You have asked or will ask the testing laboratory to let her know specifically what their error rates may be.
b. The error rate for the chromosomes testing varies, but is commonly less than one percent.
c. There are no published instances where the biopsied material has been diagnosed as aneuploid and resulted in a healthy baby.
d. She shouldn’t worry because there have not been any published reports of PGS errors
b.
An effective method for cell lysis that may enhance DNA accessibility is:
a. Hydrogen peroxide
b. Sodium chloride
c. Dimethyl sulfoxide
d. Sodium hydroxide
d.
Sodium hydroxide (NaOH) is commonly used for cell lysis in DNA extraction protocols.
In evaluating PGT-A studies, it may not be as important to consider
a. If the patients were young or older, good or poor responders
b. The total number of embryos available fresh or cryopreserved in the study and control groups
c. Whether the testing methodology is predictive
d. Observational studies that were not randomized
b.
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