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Old 08-08-2012
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Default Linkage of disease allele question.

In a family study following an AD trait through 3 generations, 2loci are compared for their potential linkage to disease locus. In the following 3- generation pedigree, shaded symbols indicate the presence of the disease phenotype, and the expression of ABO blood type and MN alleles are shown beneath each individual symbol.
Linkage of disease allele question.-linkage-q.png
Which of the following conclusions can be made about the linkage of the disease allele, ABO blood group locus, and MN locus?

A. The ABO and MN alleles are linked, but assort independently from the disease allele.
B. The ABO, MN, and disease alleles all assort independently.
C. The disease allele is linked to the ABO locus.
D. The disease allele is linked to the ABO and MN loci.
E. the disease allele is linked to the MN locus.

Above give figure is self made (that means, copied from book. So had to make myself. If you face any problem understanding it let me know)
And if you can explain your answer somewhat it would be really good.
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Old 08-08-2012
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C? ........
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should be C but hv to come at answer using elimination method
but frequency of MN specially N is higher too
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Quote:
Originally Posted by Casandra View Post
C? ........
Reason?
I am really not able to get this thing at all.


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Old 08-08-2012
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Default .

Quote:
Originally Posted by koolkiller88 View Post
Reason?
I am really not able to get this thing at all.


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A. The ABO and MN alleles are linked, but assort independently from the disease allele. -> ABO and MN are not linked, look at all cross-over throught out the pedigree
B. The ABO, MN, and disease alleles all assort independently. -> again, not true, bc you can see the some pattern/linkage btw them
C. The disease allele is linked to the ABO locus. - All subjects with the disease have AO - probably disease-causing gene and AO gene are close to each other (linked) - low chance of cross-over.
D. The disease allele is linked to the ABO and MN loci. - I can't see any linkage btw MN and the disease (lots of crossing-over btw MNs and variable disease occurance)
E. the disease allele is linked to the MN locus. - the same reason like in D

I don't feel expert on this anyhow though What is the official right answer?
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Linkage of disease allele question.-imageuploadedbytapatalk-hd1344429882.700109.jpg
That's the official answer. Sorry too lazy to write but I must say ur explanation makes more sense to me.
Thanks . In Chinese: xie xie ;-)

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