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Genetics

What percentage of newborns has a recognized structural defect?

a. 1–2%

b. 2–3%

c. 3–4%

d. 4–5%

A 40-year-old G2P1 presents at 36 weeks’ gestation with decreased fetal movement. She is diagnosed with a stillbirth and undergoes induction. The stillborn infant is noted to have low-set ears, a high arched palate, and an imperforate anus. What is the chance that the fetus has an underlying genetic abnormality?

a. 6–8%

b. 10–12%

c. 13–15%

d. 18–20%

Which of the following abnormalities can be identified by chromosomal microarray analysis but not standard karyotype?

a. Microdeletions

b. Microduplications

c. Copy number variants

d. All of the above

In what phase of cell division are oocytes arrested between birth and ovulation?

a. Prophase I

b. Anaphase I

c. Metaphase I

d. Telophase I

A 30-year-old G1 undergoes cell-free DNA screening at 12 weeks’ gestation, and the results indicate an increased risk of trisomy 18. She has an amniocentesis at 16 weeks’ gestation which confirms the diagnosis. At 32 years old, she conceives again. What is her risk of an autosomal trisomy in this pregnancy?

a. 0.25%

b. 0.5%

c. 1.0%

d. 1.5%

When major and minor sonographic markers are considered, what percentage of fetuses with the karyotype shown can be detected sonographically?

Reproduced with permission from Cunningham FG, Leveno KJ, Bloom SL, et al (eds): Genetic disorders. In William Obstetrics, 25th ed. New York, McGraw-Hill, 2018, Figure 13-3. Photo contributor: Dr. Frederick Elder.

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