An FRT flanked neo cassette and loxP site were inserted in front of exon 5, an R497X mutation was inserted in exon 6 and a loxP site was inserted downstream of exon 6 via homologous recombination. Flp mediated recombination removed the neo cassette. RT-PCR analysis indicates an upregulation of the Marveld2-d (lacking exon 4) and Marveld2-e (alternative splice of exon 6) splice variants in the inner ear of homozygous mice at P10. Western blot analysis failed to detect wild-type protein in inner ear lysates from P10 homozygous mice.