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  #1  
Old 06-22-2012
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Default A couple seeks genetic counceling because...

A couple seeks genetic counceling because both the man and the woman (unrelated to each other) are carriers of a mutation causing beta-thalassemia, an autosomal recessive condition. The couple has one son who is phenotypically normal and has been show by DNA analysis to be homozygous for the normal allele. They wish to know whether the fetus in the current pregnancy will have beta-thalassemia. Using a probe for the beta-globin gene that detects a BamH1 RFLP, the following results are obtained (see attachment). What is the best conclusion about the fetus?

a) The fetus has inherited the mutation from both parents
b) The fetus has inherited the mutation from the mother but not from the father
c) The fetus has inherited the mutation from the father but not from the mother
d) The fetus has not inherited the mutation from either parent
e) The results are inconclusive
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  #2  
Old 06-22-2012
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My pick would be C!
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Old 06-22-2012
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Yeah, its C.
thanks for the questions, mate. do you make them all up?
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Old 06-22-2012
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if son is normal, by patern,it means fathers bottom allele is normal and mothers bottom allele is normal.fetus inherit from mothers bottom allele,so top allele must to be from father,if parents are carrier and both bottom allele are normal carier is top.fetus inherit top allele from father which allele is mutated
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Old 06-22-2012
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A. The fetus has inherited the mutation from both parents.

Because they have a homozygous normal child, the first allele in the father is the bad one and the first allele in the mother is bad too.
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Its C for sure .. thanks for the questions though. Its like a good review for those of us whose exams are close.. i wish they'd ask more questions like these and less WTF questions
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Old 06-22-2012
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rapiddo look at pattern -yes u are right first alleles in both parents are mutated but fetus second allele are inherited from mother which is normal,so fetus first alele must to be from father which are mutated
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Old 06-22-2012
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I go for C..
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C...........
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  #10  
Old 06-22-2012
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C...........
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Matched!!!
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Old 06-23-2012
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Default correct answer :)

Correct answer is c) The fetus has inherited the mutation from the father but not from the mother

Mutated allele is the upper one. The fetus gets the middle one from the mother, so the upper-mutated is from father.

@smanthrav - no, this question is from Kaplan

@numbndumb - yeah, wish the same too. I'm just warming up with the questions so will be posting some more every now and then. good luck on your exam!
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