ATI RN
Genetic Disorders in Pediatrics Questions
Question 1 of 5
Which of the following fetal tissues are used for studying the fetal chromosomes:
Correct Answer: C
Rationale: Amniotic fluid (C) is used in amniocentesis to study fetal chromosomes. Rationale: It contains fetal cells (e.g., amniocytes) that can be cultured for karyotyping, unlike lymphocytes (postnatal) or cheek swabs (not fetal). Skin biopsy and bone marrow are less common prenatally.
Question 2 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 3 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 4 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 5 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.