A Trait Is Caused by a Rare Recessive Autosomal Allele

Multiple Choice

A trait is caused by a rare recessive autosomal allele with full penetrance. Practically all individuals with the trait result from matings between normal individuals. What would be the expected concordance values for monozygotic and dizygotic twins?

A) 100% for both types of twins
B) 100% for monozygotic twins and 50% for dizygotic twins
C) about 50% for both types of twins
D) 100% for monozygotic twins and 75% for dizygotic twins
E) 100% for monozygotic twins and 25% for dizygotic twins