This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
Which one of the following is false about autosomal dominant disorders. 
Select and explain. 
A. Mutated genes can express themselves in heterozygous state, B. Recurrence risk of 25% for parents with a previous affected child, C. Males and females are equally affected, D. Usually defects of structural proteins or receptors
B: Recurrence risk of 25% for parents with a previous affected child
Answer: B: Recurrence risk of 25% for parents with a previous affected child 
Explanation: Recurrence risk is 50%.