This ENU-induced mutation was isolated in a screen at the University of Pittsburgh. It is a subline of b2b1625Clo. The molecular lesion is an A to G substitution at nucleotide -3 before coding nucleotide 8456 (c.8456-3A>G, NM_001081088) in intron 44. This changes splice acceptor site AAG to TAG (which may have a different efficiency).