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Kaplan Qbank USMLE



Author11 Posts
  #1

A 30-year-old woman is phenotypically normal but had a brother who died from infantile Tay-Sachs disease (autosomal recessive lethal condition with 100% penetrance). What is the probability that this woman is a heterozygous carrier for Tay-Sachs disease?

  #2

2/3

  #3

2/3

___________________
I hear and I forget. I see and I remember. I do and I understand.
--Confucius

  #4

2/3 means can we say 50%?
thanx.

  #5

no we can't, 2/3=67%

  #6

oh ok thanx.
so what about 50% how can we mention this?

  #7

50% is 1/2

___________________
I hear and I forget. I see and I remember. I do and I understand.
--Confucius

  #8

ok thanx.

  #9

why 2/3 how do you get it please

___________________
elsa

  #10

her brother had the ds => both her parents r carriers
then 4 possibllities wud be AA, Aa, Aa, and aa
she does not ve the ds => she is either normal or a carrier(aa is ruled out)
possibility of being a carrier is 2/3

___________________
I hear and I forget. I see and I remember. I do and I understand.
--Confucius

  #11

thanks!

___________________
elsa







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