Which, If Any, of the Following Statements Is False

Multiple Choice

Which, if any, of the following statements is false?

A) A null allele is one where the gene has been deleted or received an inactivating mutation causing complete loss of gene function.
B) Inactivating point mutations are a common cause of pathogenesis in recessively inherited disorders.
C) Inactivating point mutations are a common cause of pathogenesis in dominantly inherited disorders.
D) When a gain-of-function allele is known to be pathogenic in a single gene disorder, a heterozygote will always show disease symptoms.