Autosomal dominant disorders

I am a bit stuck on this question. Would I be correct in saying that (D) was the answer, as although autosomal dominant rarely skips generations, it COULD skip generations on the off-chance that the children didn't inherit the disorder.

9. Which one of the following statements about autosomal dominant disorders is INCORRECT?
(A) They get progressively more severe through generations.
(B) They have a 0.5 probability of being passed on from a heterozygous person with the disease.
(C) They are often caused by a gain-of-function mutation.
(D) They appear in all generations of a pedigree.

(edited 9 years ago)

Reply 1

Hype en Ecosse

20

Original post by intex

I am a bit stuck on this question. Would I be correct in saying that (D) was the answer, as although autosomal dominant rarely skips generations, it COULD skip generations on the off-chance that the children didn't inherit the disorder.

9. Which one of the following statements about autosomal dominant disorders is INCORRECT?
(A) They get progressively more severe through generations.
(B) They have a 0.5 probability of being passed on from a heterozygous person with the disease.
(C) They are often caused by a gain-of-function mutation.
(D) They appear in all generations of a pedigree.

The answer is B, because the diseased allele has a 50% chance of being passed on (since there's only 2 choices within the genome).
It's not D because of a phenomenon called "non-penetrance", where a person can have the diseased allele, but not present with the disease.

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Reply 2

intex

OP

Original post by Hype en Ecosse

The answer is B, because the diseased allele has a 50% chance of being passed on (since there's only 2 choices within the genome).
It's not D because of a phenomenon called "non-penetrance", where a person can have the diseased allele, but not present with the disease.

Posted from TSR Mobile

So what you are saying is that D is the INCORRECT one?