The human β-globin wild-type allele and a certain mutant allele are identical in sequence except for a single base-pair substitution that changes one nucleotide at the end of intron 2. The wild-type and mutant sequences of the affected portion of pre-mRNA are

                   Intron 2                        Exon 3        _
wild type     5′-CCUCCCACAG      CUCCUG-3′
mutant.       5′-CCUCCCACUG      CUCCUG-3′

This is one example of how DNA sequence change occurring somewhere other than in an exon can produce mutation. List other kinds of DNA sequence changes occurring outside exons that can produce mutation. In each case, characterize the kind of change you would expect to see in mutant mRNA or mutant protein.