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Old 08-09-2011
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DNA Two Hit Hypothesis Confusion!

A 21-year-old Caucasian female has a strong family history of breast cancer and sarcomas. You strongly suspect Li-Fraumeni syndrome. Blood cells from a serum sample would most likely demonstrate which of the following?

A.) One allele deletion

B.) Two allele deletion


The answer is A.), but i put B.) because if you want P53 to totally lose its function, then by the time you take blood sample, both tumor suppressor genes should already lost their functions, right?

Or this is the difference between the word " deletion" and " acquired second mutation"??
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Old 08-10-2011
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ya ths ans will be one allele deletion, y bcos in two hit theory one allele deleted before birth itself, another will be delete after the birth. in somatic cells only one allele will be deleted. only cancer cells will have two alleles deleted. are u understand. are need further expl.
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Old 08-10-2011
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Quote:
Originally Posted by chienpolska View Post
A 21-year-old Caucasian female has a strong family history of breast cancer and sarcomas. You strongly suspect Li-Fraumeni syndrome. Blood cells from a serum sample would most likely demonstrate which of the following?

A.) One allele deletion

B.) Two allele deletion


The answer is A.), but i put B.) because if you want P53 to totally lose its function, then by the time you take blood sample, both tumor suppressor genes should already lost their functions, right?

Or this is the difference between the word " deletion" and " acquired second mutation"??
i also made same mistake in this q
the thing to notice tht pt has a HISTORY not tht she is presenting with any tumour so unless u ve a HISTORY but no tumor till date ur carrying one mutant allele tht u got in ur genes
n if this girl later develops breast cancer there the two hit phenomena is applied where due to any event in life led to loss of the other normal allele
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