ATI RN
Pediatric Genetic Disorders Questions
Question 1 of 5
Which banding technique stains heterochromatin (dark) and euchromatin (light)?
Correct Answer: C
Rationale: G-banding (C) stains heterochromatin dark (G-positive) and euchromatin light. Rationale: Giemsa stains AT-rich, gene-poor heterochromatin dark, while GC-rich, gene-active euchromatin stays light, standard for karyotyping.
Question 2 of 5
A healthy mother is married to a man who has a roberstonian 14,21 balance. What is the possibility to have a baby with down syndrome?
Correct Answer: D
Rationale: 1/6 ( missing in OCR) is correct. Rationale: 45, XY, t(14;21) produces 6 gametes: normal, t(14;21), 14, 21, null 14, null 21. With 46, XX, only 21+t(14;21) yields 47, +21 (Down), 1/6 chance.
Question 3 of 5
Baby with large placenta, with or without microcephaly:
Correct Answer: A
Rationale: Diandric (A, paternal triploidy) fits. Rationale: 2 paternal + 1 maternal sets (e.g., dispermy) cause large placenta, variable fetal size.
Question 4 of 5
The clinical features of patients with Marfan syndrome are caused by unusually stretchable connective tissue. The most observed features in Marfan syndrome affect the eye, the skeleton, and the cardiovascular system. This is an example of:
Correct Answer: B
Rationale: Marfan syndrome’s multiple effects (eye, skeleton, heart) from FBN1 mutations exemplify pleiotropy (B). Rationale: One gene mutation (FBN1) affects connective tissue across systems, unlike allelic heterogeneity (different mutations, same phenotype) or anticipation (worsening generations).
Question 5 of 5
A 17-year-old Tanner stage 2 female presents with a history of bilateral spontaneous milky discharge from her breasts for 2 months. Menarche was at age 12 years, and her periods had been regular until 4 months before this visit to your office. In addition, she complains of headache on awakening for the past 2 weeks. The most useful screening test is
Correct Answer: C
Rationale: Galactorrhea (milky discharge), amenorrhea, and headaches suggest hyperprolactinemia, possibly from a pituitary adenoma. Serum prolactin level (C) is the most useful initial test. Rationale: Pregnancy tests (A, B) are relevant but less likely given Tanner stage 2 and no sexual history implied; prolactin directly assesses the suspected cause, unlike estrogen (D) or LH (E, not listed).