ATI RN
Common Pediatric Genetic Disorders Questions
Question 1 of 5
The DiGeorge/Shprintzen syndrome is caused by a deletion in which chromosome?
Correct Answer: D
Rationale: DiGeorge syndrome (22q11.2 deletion) affects chromosome 22.
Question 2 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 3 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 4 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.
Question 5 of 5
The karyotype where euchromatic regions stain more darkly and the light regions are heretochromatin is:
Correct Answer: D
Rationale: R-banding is correct. Rationale: Euchromatin is gene-rich and active, staining dark in R-banding with reverse Giemsa or fluorescent dyes, while heterochromatin (repetitive, inactive) stains light.