ATI RN
Genetic Disorders in Pediatrics Questions
Question 1 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 2 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 3 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.
Question 4 of 5
Pair homologous chromosomes in metaphase I, how many double strand DNA in it?
Correct Answer: D
Rationale: A homologous pair in metaphase I has 2 chromosomes, each with 2 chromatids (4 double-stranded DNA molecules total). (4) is correct. Rationale: Post-S phase, each chromosome duplicates; a pair (e.g., chromosome 1 from mom and dad) has 4 double helices before separation.
Question 5 of 5
Which of the following deletion of the p arm causes abnormality?
Correct Answer: D
Rationale: Deletion of 16p (D) causes abnormalities (e.g., 16p11.2 deletion syndrome). Rationale: 13p, 14p, 15p are mostly heterochromatic (fewer genes), often benign when deleted; 16p has critical genes, leading to developmental issues.