A floxed neomycin resistance cassette was inserted upstream of exon 10. Exon 11 was replaced with a modified one in which a TG were deleted. This mutation mimics the mutation found in patients with Naxos disease and results in a premature stop codon in exon 12. Flp-mediated recombination removed the selection cassette. RT-PCR confirmed reduced transcript expression. (J:222025)