Question

Problem 46) achondroplasia is the most common mendelian form of genetic dwarfism and is inherited as an autosomal dominant disorder. it has been found that new achondroplasia mutations are usually inherited from the father, particularly older fathers. why might new mutations arise in older males?

Answer 1

I think the answer is: Older men produce sperm that have originated from more prior mitotic cell divisions in the germ line, so there are more opportunities for mutations to occur.

If the producing sperm at 15 years old, sperm of 20 years old man is made from 5 years of division.
When he is 40 years old, the sperm is made from sperm that divides for 25 years. So, 40 years old man sperm should accumulate more mutation as it divides more.