ATI RN
Pediatrics Genetics Questions
Question 1 of 5
The figure below is the pedigree demonstrating the recurrence of Osteogenesis imperfecta in children with their father unaffected (arrow)
Correct Answer: A
Rationale: OI is AD. Unaffected father with affected kids suggests germline mosaicism; figure unavailable.
Question 2 of 5
A cell is in GO phase. How many chromosomes does it have?
Correct Answer: A
Rationale: G0 is a quiescent phase with no division; a human somatic cell has 46 chromosomes (A). Rationale: G0 cells are diploid (2n=46), not haploid (23) or replicated (92, G2 phase). Answer matches normal somatic count.
Question 3 of 5
Which of the following genetic changes is associated with a female whose karyotype is 46, XY?
Correct Answer: A
Rationale: 46, XY female indicates SRY mutation (A). Rationale: SRY on Y determines maleness; mutations prevent testis development, resulting in female phenotype despite XY karyotype. Monosomy X is 45, X; Triple X is 47, XXX.
Question 4 of 5
Which of the following karyotype is expected to be associated with abnormal phenotype [Note: 't' is translocation, and 'del' is deletion]:
Correct Answer: A
Rationale: 46, XX, del5p (A) causes Cri du Chat syndrome. Rationale: 5p deletion leads to severe phenotypes (cat-like cry, microcephaly). Balanced translocations (B, D) are normal; 22p deletion (C) is often benign (heterochromatic).
Question 5 of 5
47 XYY occurs due to:
Correct Answer: C
Rationale: Paternal nondisjunction (C) causes 47, XYY. Rationale: Meiosis II nondisjunction in father produces YY sperm (24, YY), fertilizing X egg (23, X), yielding 47, XYY. Chimerism or UPD don’t fit; maternal nondisjunction gives XXY.