Recombinase-mediated cassette exchange was used to replace exon 2 with a loxP site, the FLAG-tagged full length human SCN5A with a G to A mutation (c.3823G to A), an FRT-flanked hygro cassette and a loxP site. The mutation results in the amino acid substitution of asparagine for aspartic acid at position 1275 (D1275N). (J:189389)