Molecular Biology/Genetics USMLE Step 1 Practice Question
A 28-year-old woman delivers an infant with hypotonia, upslanting palpebral fissures, and a single palmar crease. Vital signs show HR 120/min, RR 28/min, and mild hypothermia at 36.2°C. Serum TSH is normal, excluding congenital hypothyroidism. Karyotype reveals 46 chromosomes with translocation of chromosome 21 material onto chromosome 14. The mother's karyotype is normal. Which of the following best describes this chromosomal abnormality?
Answer choices
- AMitochondrial heteroplasmy
- BBalanced Robertsonian translocation in a parent with unbalanced segregation in the childCorrect answer
- CTriplet repeat expansion
- DIsochromosome formation
- ESomatic mosaicism
- FUnbalanced translocation between chromosomes 21 and 22 with maternal origin
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