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#1
05-30-2011
 USMLE Forums Addict Steps History: 1 + CS Posts: 113 Threads: 8 Thanked 88 Times in 61 Posts Reputation: 98
mucopolysaccharidosis Type II & genetics

Hunter syndrome, or mucopolysaccharidosis Type II, is a rare disease that it shows X-linked recessive inheritance. In a female with 2 brothers with the diasese, which of the following is correct?

a) The probability that she is a carrier is 2/3.
b) If she is a carrier then the probability that each of her sons will be affected is 1 in 4.
c) If she is a carrier then the probability that each of her daughters will be a carrier is 1 in 4.
d) Before any carrier testing is carried out the woman can be correctly informed that the probability that her first son will be affected is 1 in 4.
 The above post was thanked by: apx85 (05-30-2011), usluipek (05-30-2011)

#2
05-30-2011
 USMLE Forums Master Steps History: 1+CK+CS+3 Posts: 1,357 Threads: 194 Thanked 3,259 Times in 881 Posts Reputation: 3269

no idea which one is the right answer...

the probability that her son will be affected is 1 in 2
the probability that her daughter will be carrier is 1 in 2
#3
05-30-2011
 USMLE Forums Master Steps History: 1+CK+CS+3 Posts: 1,175 Threads: 38 Thanked 852 Times in 478 Posts Reputation: 862

Im stuck between A) and C)

What's with the recent flux of genetics questions?
#4
05-30-2011
 USMLE Forums Guru Steps History: --- Posts: 332 Threads: 48 Thanked 168 Times in 107 Posts

Pls keep genetic calculation coming, the more the better!
#5
05-30-2011
 USMLE Forums Newbie Steps History: Step 1 Only Posts: 5 Threads: 2 Thanked 15 Times in 3 Posts Reputation: 25

a) The probability that she is a carrier is 2/3.---should be 1/2
b) If she is a carrier then the probability that each of her sons will be affected is 1 in 4.---if she's a carrier, Xx, then son will be 1/2 chance to have dz
c) If she is a carrier then the probability that each of her daughters will be a carrier is 1 in 4.--daughter would be 1/2 carrier
d) Before any carrier testing is carried out the woman can be correctly informed that the probability that her first son will be affected is 1 in 4.--this one is right. possibility to be a carrier 1/2, transfer the bad one to don is 1/2, so 1/2*1/2=1/4
 The above post was thanked by: apx85 (05-30-2011), bebix (05-30-2011), kiki (05-31-2011), struggle (05-30-2011), usluipek (05-30-2011)
#6
05-30-2011
 USMLE Forums Master Steps History: 1+CK+CS+3 Posts: 1,357 Threads: 194 Thanked 3,259 Times in 881 Posts Reputation: 3269

Quote:
 Originally Posted by 123to789 a) The probability that she is a carrier is 2/3.---should be 1/2 b) If she is a carrier then the probability that each of her sons will be affected is 1 in 4.---if she's a carrier, Xx, then son will be 1/2 chance to have dz c) If she is a carrier then the probability that each of her daughters will be a carrier is 1 in 4.--daughter would be 1/2 carrier d) Before any carrier testing is carried out the woman can be correctly informed that the probability that her first son will be affected is 1 in 4.--this one is right. possibility to be a carrier 1/2, transfer the bad one to don is 1/2, so 1/2*1/2=1/4
you´re absolutely right. Thanks!
 The above post was thanked by: leo lakhani (05-30-2011)

 Tags Biochemistry-, Genetics-, Syndromes-Acronyms

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