ATI RN
Common Pediatric Genetic Disorders Questions
Question 1 of 5
Large triplet repeat expansions can be detected by:
Correct Answer: C
Rationale: Southern blotting is used for large repeat expansions (e.g., Huntington’s), as PCR may fail with very large repeats.
Question 2 of 5
Marfan syndrome is caused by mutations in the gene which encodes
Correct Answer: D
Rationale: Marfan syndrome results from FBN1 mutations affecting fibrillin, a connective tissue protein.
Question 3 of 5
Which of the following karyotypes is diagnostic of Down syndrome?
Correct Answer: A
Rationale: 46,XX,der(14;21)+21 indicates a translocation Down syndrome with an extra 21, totaling 47 chromosomes’ worth of material.
Question 4 of 5
5-month-old girl has bilateral retinoblastoma. Neither parent has a history of having had retinoblastoma. Chromosomal analysis of the patient’s stimulated peripheral blood lymphocytes is done; the photograph is of a representative karyotype. Which of the following critical events has most likely resulted from an aberration involving chromosome 13?
Correct Answer: D
Rationale: Bilateral retinoblastoma often involves a germline RB1 (tumor suppressor) mutation on 13q14, with a second hit (loss) in somatic cells.
Question 5 of 5
Which of the following mutations is most likely to be lethal?
Correct Answer: D
Rationale: Frameshift mutations (e.g., 1-nucleotide insertion) disrupt the reading frame, often more lethal than substitutions or in-frame deletions.