A Couple Comes to You for Advice About Genetic Testing

A couple comes to you for advice about genetic testing for a rare early- onset dominant condition. The paternal grandfather had the condition, but no one else in the family has had it including the male partner in this couple. Do you recommend testing? Why?

A) yes, testing is expensive, but worth the price, even when unnecessary
B) no, the male partner is definitely a carrier and so the outcome is certain
C) yes, the male partner is definitely a carrier
D) no, we can deduce that neither partner has a disease allele
E) no, both parents would have to have the disease allele to have an affected child