This ENU-induced mutation was isolated in a screen at the University of Pittsburgh. The molecular lesion is a T to C substitution at nucleotide +2 after coding nucleotide 606 (c.606+2T>C, NM_031397) in intron 5. This changes splice donor site G-GT to G-GC (which is assumed to be less efficient). (J:175213) Additional incidental mutations were detected in sequencing for the causative mutation, Bicc1b2b222Clo, and may be present in stocks carrying this mutation.