A floxed neo cassette was inserted downstream of exon 6. The genomic sequence corresponding to exons 7 through 10 was replaced with the corresponding human sequence with nucleotide substitutions that result in the amino acid substitution of valine for methionine at position 694 (p.M694V). The amino acid substitutions within exon 10 occur in the human-specific B30.2 domain. Cre-mediated recombination removed the neo cassette.