Arginine codon 304 (AGG) in exon 7 was changed to tryptophan (TGG) (c.910A>T:p.R304W). A loxP site, an FRT site flanked protamine-cre cassette, a neomycin resistance gene cassette and a second loxP site were inserted in opposite transcriptional orientation into intron 7. The floxed cre plus neo cassette pair was self-excised in male germline through the protamine promotor-driven expression of Cre. The mutation is the equivalent of the same human mutation associated with tubular aggregate myopathy (TAM) and Stormorken syndrome (STRMK).