ATI RN
Genetic Disorders in Pediatrics Questions
Question 1 of 5
In the following partial sequence of mRNA, a mutation of the template DNA results in a change in codon 91 to UAA. What type of mutation is it? | 88 | 89 | 90 | 91 | 92 | 93 | 94 | GUC | GAC | CAG | UAG | GGC | UAA | CCG |
Correct Answer: C
Rationale: UAG is a stop codon; changing codon 91 to UAA (another stop) is nonsense, causing premature termination.
Question 2 of 5
The most commonly used stain for metaphase chromosomes is?
Correct Answer: B
Rationale: Giemsa stain (B) is standard for G-banding in karyotyping. Rationale: Giemsa produces dark (G-positive) and light bands, widely used for chromosome identification. Quinacrine (Q-banding) and trypsin (pre-treatment) are less common alone.
Question 3 of 5
The most common aneuploidy that infants can survive with is (most compatible with life)?
Correct Answer: C
Rationale: Trisomy 21 (Down syndrome, C) is most survivable. Rationale: Edwards (18) and Patau (13) are often lethal early; Turner (45, X) is viable but less common than Down syndrome, which has milder effects and higher live birth rates.
Question 4 of 5
46 XX male syndrome is a rare condition, described by De la Chapelle et al. in 1964 where the individual has phenotypically male characteristics. It occurs in one out of every 20,000-25,000 newborn males. This condition could be related to:
Correct Answer: C
Rationale: SRY gene (C) causes 46, XX males. Rationale: SRY translocation from Y to X or autosome in XX individuals triggers male development despite no Y chromosome. Turner is 45, X; Rb is unrelated (retinoblastoma).
Question 5 of 5
Which one of the following karyotypes is most likely to be found in normal human ovarian progenitor cell?
Correct Answer: C
Rationale: 46, XX (C) is normal for ovarian cells. Rationale: Ovarian progenitor cells (somatic) in females are diploid (2n=46, XX). 23, X is gametic; 46, XY is male; 22, Y is inviable.