ATI RN
Genetic Pediatric Questions
Question 1 of 5
Which one of the following causes a frame-shift mutation?
Correct Answer: C
Rationale: Deletion (if not in multiples of 3) shifts the reading frame; substitutions (A-E) do not.
Question 2 of 5
The study of chromosomes and cell division is called:
Correct Answer: A
Rationale: Cytogenetics (A) studies chromosomes and cell division. Rationale: Cytology is broader (cell biology), and pedigree is inheritance charting. Cytogenetics focuses on karyotypes and meiosis/mitosis.
Question 3 of 5
The most stable chromosome of the following is:
Correct Answer: C
Rationale: 45, XY, t(14,21) (C) is a balanced Robertsonian translocation, phenotypically normal. Rationale: 46, 0Y is inviable (no X), trisomy 14 is lethal, but t(14;21) carriers have normal gene content despite 45 chromosomes.
Question 4 of 5
If one of the parent who carries balanced reciprocal translocation mates with a partner with normal karyotype. What is the risk of having a fetus with abnormal chromosomal complement?
Correct Answer: D
Rationale: 1/2 (D) is approximate. Rationale: Balanced translocation (e.g., t(11;22)) with normal partner yields 4 gamete types via adjacent/alternate segregation: 50% balanced (normal or carrier), 50% unbalanced (duplication/deletion), risking abnormal fetuses. Exact risk varies, but 1/2 is typical.
Question 5 of 5
A chromosomal analysis is obtained on a young woman with mild signs of Patau syndrome and reveals a 46,XX/47,XX +13 mosaic karyotype. Nondisjunction is most likely to have occurred in:
Correct Answer: B
Rationale: Mitosis post-fertilization (B) causes mosaicism. Rationale: 46, XX/47, XX, +13 arises when nondisjunction in an early mitotic division of a 46, XX zygote loses or gains a 13, creating two cell lines. Meiotic errors produce uniform aneuploidy.