Down's syndrome is caused by an extra copy of chromosome number 21. What percentage of offspring produced by an affected mother and a normal father would be affected by this disorder?

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Accepted Answer

100%. A mother with Down's syndrome has trisomy 21, meaning her eggs will each contain an extra chromosome 21. When fertilized by a normal father's sperm, every child will inherit that extra copy and be affected.

Down's syndrome is caused by an extra copy of chromosome number 21. What percentage of offspring produced by an affected mother and a normal father would be affected by this disorder?

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