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30 yr old man phenotypically normal, with 2 siblings died from tay sachs. what is the risk that this man is a heterogygous carrier of disease causing mutation
1) 1/4
2) 1/2
3) 2/3
4) 3/4
5) not elevated above the general population

3)2/3
Either he is homozygous normal or hetreozygous carrier..in that either he got the defective allele frm mother OR father so TOTAL 3 possibilities....and 2 of them lead to heterozygous state so 2/3.

333

2 may be the answer.

ya 2/3 is the answer.
sorry for mistake.

yes 2/3 is the right answer.