ATI RN
Genetic Pediatric Questions
Question 1 of 5
Recombination occurs in:
Correct Answer: A
Rationale: Recombination (crossing over) occurs in pachytene of prophase I. 'A' is correct. Rationale: In meiosis I, leptotene condenses chromosomes, zygotene pairs them, pachytene facilitates crossing over via chiasmata, diplotene reveals chiasmata, and diakinesis prepares for separation.
Question 2 of 5
SMOH gene located in pseudoautosomal in Y chromosome, do you expect that it will be located in 46 XX?
Correct Answer: A
Rationale: Yes (A), pseudoautosomal regions (PAR) are on both X and Y. Rationale: PAR genes (e.g., SHOX, not SMOH—a typo?) are homologous on X and Y, present in 46, XX females, unlike Y-specific genes.
Question 3 of 5
Tetraploidy results from:
Correct Answer: B
Rationale: Endomitosis post-fertilization (B) causes tetraploidy (4n=92). Rationale: Zygote duplicates chromosomes without division; dispermy yields triploidy, not 4n.
Question 4 of 5
Possibility of combinations for diploid cell with 10 chromosomes?
Correct Answer: D
Rationale: 2^n where n=5 (haploid from 2n=10) gives 32 (D). Rationale: Independent assortment of 5 pairs yields 2^5 = 32 gamete combinations.
Question 5 of 5
You are asked to consult about a 2-month-old girl with hypotonia, seizures, and an elevated plasma lactate (8 mM/L, normal <2). Brain MRI shows a thin corpus callosum but no other abnormalities. You suspect pyruvate dehydrogenase deficiency. Which of the following is the most likely mode of inheritance in this infant?
Correct Answer: C
Rationale: Pyruvate dehydrogenase deficiency (PDH) is often autosomal recessive (C), though X-linked forms exist. Rationale: E1 subunit mutations (PDHA1, X-linked) are common, but autosomal recessive (other subunits) fits sporadic cases in females without male bias; symptoms match metabolic defect.