Dr_Cosme wrote:
for the looks of that pedigree, is an autosomal dominat disease. The only disease that came up in my mind when I saw this question is Li-Fraumeni Syndrome. I believe the answer is B, because I ruled out the other possibilities. Anyway, that is what I chose when I took the test.
What was the rationale behind ruling out choice E - variable expressivity? That's waht I chose. please explain.
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| pr20
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I chose answer D-multifactorial inheritance in my exam thinking it as Li-Fraumeni syndrome,a familial cancer syndrome which shows multifactorial inheritance.
I ruled out choices A and C.I think variable expression is the degree of variance of phenotypic expression of a same disease in different members within a family or between the families.For example,in hemochromatosis,some members within a family or between the families may be severely affected and some may be mildly affected.Variable expression--->variance in expression(severity)of a same disease in the related individuals.Variable expression within a family can be due to environmental influences,heteroplasmy,or modifier loci and variable expression between families can be due to allelic heterogenicity.But this pedigree shows many different diseases running in the families.So i ruled out choice E.
I don't have the slightest clue why B is the correct answer.Am i missing something?
Anyway genetics really is a mysterious subject
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| Tiff
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I too am thinking Li Fraumeni. I thought of D - multifactorial inheritance but then I thought that it would have to incude other disorder other than cancers. I'm really not sure.  Does anyone know what the right answer is?
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| pr20
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Tiff wrote:I too am thinking Li Fraumeni. I thought of D - multifactorial inheritance but then I thought that it would have to incude other disorder other than cancers. I'm really not sure. Does anyone know what the right answer is?
Li Fraumeni syndrome is an autosomal dominant disorder in which patients are predisposed to different types of cancers and the onset of cancers is usually at a young age.So the pedigree fits Li Fraumeni syndrome.
Apart from cancers of different types,I don't think there will be any other significant associated disorders in Li Fraumeni syndrome.
Anyone can add inputs and explain the correct answer.
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| Tiff
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pr20 wrote:Tiff wrote:I too am thinking Li Fraumeni. I thought of D - multifactorial inheritance but then I thought that it would have to incude other disorder other than cancers. I'm really not sure. Does anyone know what the right answer is? Li Fraumeni syndrome is an autosomal dominant disorder in which patients are predisposed to different types of cancers and the onset of cancers is usually at a young age.So the pedigree fits Li Fraumeni syndrome. Apart from cancers of different types,I don't think there will be any other significant associated disorders in Li Fraumeni syndrome. Anyone can add inputs and explain the correct answer.
Yeah I agree that it's Li Fraumeni. What I mean is that I'm not sure what multifactorial inheritence (answer choice D) really entails. I've always thought that for multifactorial there would have to be different disorders associated - like cancer and some other genetic disease. I chose E because it is associated with cancer syndromes and that is waht Li Fraumeni is.
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