Tricky genetics question

[LuckiestOne]

---

Members don't see this ad.

http://imageshack.us/photo/my-images/513/photo3yl.jpg/

The answer choices are:

A. anticipation
B. genetic heterogeneity
C. incomplete penetrance
D. multifactorial inheritance
E. variable expressivity.

What do you guys think the best answer is, and why? I've been searching but everyone's giving all different answers!

 

[LuckiestOne]

I would have put Variable Expressivity. Family has a mutation predisposing to cancer (Li-Fraumeni?), which is being expressed in different tissues with different malignancies. What's the correct answer?

Hey, thanks for your reply. We actually don't know the real answer b/c it is an NBME question, they don't provide you with answers. I just wanted to see what other people come up as answers.

 

[Phloston]

I would have put Variable Expressivity. Family has a mutation predisposing to cancer (Li-Fraumeni?), which is being expressed in different tissues with different malignancies. What's the correct answer?

That sounds correct. Definitely LF syndrome.

Slightly tricky in the sense that variable expressivity (variable expression) typically refers to the varying severity of phenotype (e.g. Marfan's syndrome), but it can also refer to the nature of the phenotype.

So p53 is mutated in this family, but the nature of the phenotypic expression is variable.

Therefore, variable expression is correct.

 

[Morsetlis]

I'd agree with VE. Anticipation shows a gradual decrease in age of onset and severity of symptom, either following a maternal or paternal pattern. Incomplete penetrance would show similar symptoms but missing "holes" in phenotype expressivity. Genetic heterogeneity would be something like the CFTR gene or Retinitis Pigmentosa, resulting in similar symptoms but due to defects in different genes. Multifactorial inheritance broadens the scope to non-genetic (such as environmental) bases of inheritance, which could be correct for cancer but the broad range of expression of the phenotype in this case makes VE the more correct answer.

 

[Boardz]

http://imageshack.us/photo/my-images/513/photo3yl.jpg/

The answer choices are:

A. anticipation
B. genetic heterogeneity
C. incomplete penetrance
D. multifactorial inheritance
E. variable expressivity.

What do you guys think the best answer is, and why? I've been searching but everyone's giving all different answers!

very difficult question to me. I would go with A. But E is true as well, as far as I can tell. we might never know...