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Posted by Thomas Lawton  |  7 Dec 2025
7 Dec 2025

Answer is wrong

Karyotyping the mother is NOT the correct tool for estimating the risk of Down syndrome in her fetus.

The mother is phenotypically normal, so she cannot have full trisomy 21 herself.

The only scenario where the mother's karyotype matters is if she carries a balanced Robertsonian translocation involving chromosome 21 — but this is rare, and the question gives no suggestion of such.

The given answer confuses:

  • maternal meiotic nondisjunction risk (age-related, statistical)
  • vs.
  • heritable translocation Down syndrome (very rare)
Question:
A 28 year old woman presents to your office with concerns about her pregnancy. She is in her second trimester. Her family history is significant for Down syndrome in her older sister. The age of her mom at the time of her sister’s birth was thirty-nine. What tool would you use to quantify the risk of this patient's baby developing Down syndrome?
Options:
A)Amniocentesis
B)Ultrasound
C)Maternal serum quadruple screening
D)Genetic familial history analysis
E)Karyotyping of mother's cells
→ View this question

Answer is wrong

Karyotyping the mother is NOT the correct tool for estimating the risk of Down syndrome in her fetus.

The mother is phenotypically normal, so she cannot have full trisomy 21 herself.

The only scenario where the mother's karyotype matters is if she carries a balanced Robertsonian translocation involving chromosome 21 — but this is rare, and the question gives no suggestion of such.

The given answer confuses:

  • maternal meiotic nondisjunction risk (age-related, statistical)
  • vs.
  • heritable translocation Down syndrome (very rare)
Question:
A 28 year old woman presents to your office with concerns about her pregnancy. She is in her second trimester. Her family history is significant for Down syndrome in her older sister. The age of her mom at the time of her sister’s birth was thirty-nine. What tool would you use to quantify the risk of this patient's baby developing Down syndrome?
Options:
A)Amniocentesis
B)Ultrasound
C)Maternal serum quadruple screening
D)Genetic familial history analysis
E)Karyotyping of mother's cells
→ View this question