Homologous recombination was used to insert a loxP site, FRT site flanked neomycin resistance gene cassette, an altered exon 3 with a T-to-A point mutation at position 616 (c.616T>A), which results in a substition of phenylalanine with isoleucine at amino acid position 206 (p.F206I), and a silent mutation to introduce a restriction site, and a second loxP site. This mutation is the equivalent of the human p.F613I mutation, a rare missense variant identified in a patient with sporadic late-onset focal dystonia. Western blot analysis of brain tissue shows reduced Torsin A protein levels.