robin082006
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a child with Tay Sachs, the risk that his grandmother is a carrier is
a. 100%
b. 75%
c. 50%
d. 25%
e. 0%
f. 67%
g. 33%
explain
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| sarika
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d.25%
Just my speculation
since its an autosomal disease there is a 100% chance that child's parents are carrier.
Now because parent is a carrier, he must have got it from either his mom(50%chance) or dad (again another 50% chance).
So theres a 25% chance that grandmother was carrier and 25% chance that she was homozygous for the disease,
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| mjl1717
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That was good playing with numbers.
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| krsna
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yup 25 pc it must be.
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| robin082006
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think again, why not 50%?
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| vallia
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children with Tay Sachs disease die at 4 years old so, if the grandmother or grandfather procreated ,one of them must of have been heterosygous not homosygous. So is 50%that it was the grandmother and 50% that it was the grandfather.
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| sarika
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vallia i think thats a very good point
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| docarchana
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can someone explain this q plzz..
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| ing
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The child's parents are carriers. child's mother can inhereted the disease gene either from the child grandma or grandpa. the grandparents have lived long enough to prove that both of them either are carriers or normal. so 50% should be right.
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