This ENU-induced mutation was isolated in a screen at the University of Pittsburgh. The molecular lesion is a T to C substitution at coding nucleotide 1645 in exon 19 of the cDNA (c.1645T>C, NM_026319). This changes the tryptophan residue to arginine at position 549 of the encoded protein (p.W549R). (J:175213) Additional incidental mutations were detected in sequencing for the causative mutation, Ift74b2b796Clo, and may be present in stocks carrying this mutation.