ATI RN
Pediatric Genetic Questions
Question 1 of 5
All the following are characteristic features of Turner syndrome EXCEPT
Correct Answer: C
Rationale: Turner syndrome (45,X) includes normal IQ (A), low-set ears (B), neck webbing (D), and hand puffiness (E); triangular face (C) is not typical. Rationale: Face is often broad.
Question 2 of 5
Genetic anticipation is best described as
Correct Answer: A
Rationale: Genetic anticipation occurs in trinucleotide repeat disorders, where repeat expansion increases severity or lowers onset age in subsequent generations (e.g., Huntington’s disease). It’s not a disorder, nor tied to sex-specific penetrance or imprinting.
Question 3 of 5
A newborn infant is noted to have dysmorphic features. The pregnancy was complicated by breech presentation, decreased fetal movements, and polyhydramnios. The child demonstrates hypotonia, a flat face, flattened occiput, epicanthal folds, and abdominal distention. The most likely cause of this child's dysmorphology is
Correct Answer: D
Rationale: Trisomy 21 (Down syndrome) matches these features: hypotonia, flat face, epicanthal folds, and polyhydramnios due to GI issues (e.g., duodenal atresia). Trisomy 13 and 18 (Edwards) have distinct, more severe anomalies. Trisomy 8 is rarer and less consistent with this presentation.
Question 4 of 5
Which of the following variants would you expect could to be most common:
Correct Answer: D
Rationale: C>T transitions are the most common DNA variants in humans, often due to deamination of cytosine to thymine, a frequent spontaneous mutation.
Question 5 of 5
A couple approached you because of a current pregnancy and a family history with phenylketonuria (PKU). The mother told you that her sister is affected with PKU and the father told you that his uncle is affected with PKU. You performed an ultrasound and the fetus turned out to be a female. What is the risk for the couple to have UNAFFECTED FEMALE with PKU? Assume a population frequency of 1/100? Note: PKU is an autosomal recessive disease.
Correct Answer: D
Rationale: Mother’s sister affected: mother’s carrier chance = 2/3. Father’s uncle affected: father’s carrier chance ≈ 1/100 (population frequency, distant relative). Both carriers = 2/3 × 1/100 = 2/300. Unaffected child = 3/4 (FF or Ff). Female = 1/2. Total = 2/300 × 3/4 × 1/2 = 1/6.