The gene was targeted with a construct containing the following elements: a loxP site, the wildtype cDNA, an internal ribosomal entry site (IRES), an enhanced green fluorescent protein (eGFP) reporter gene, an FRT site flanked neomycin resistance gene, a second loxP site, and the portion of the human cDNA representing a (GCG)7 alanine codon expansion. This was targeted to immediately downstream of the ATG start codon in exon 1 and adds 7 alanines to the endogenous 10. Subsequent Flp- and Cre-mediated recombination removed the neo cassette and the wildtype cDNA and eGFP insertions. Immunoblots using antibodies specific to the alanine expansion confirmed expression of this allele. This alanine expansion allele mimics a mutation found in oculopharyngeal muscular dystrophy (OPMD) patients.