Mutation in the neural specific exons.
Defective P element, of around 900bp, inserted in the 5' leader sequence of shakB, 28bp from the start of the P2.4 cDNA.
The DLMs do not respond to brain shocks and the TTMs respond only occasionally and then with a longer than normal latency.
Non jumper.
P{Δ2-3}99B induced revertants occur at 1% and have lost the P element insertion.