Mice carrying the dominant mutation lightning bolt tail have variable-length kinked tails, curved spine, and abnormal spinal vertebral bodies. When picked up by the tail, carriers orient their rear legs in abnormal positions. Only 25% of the offspring of heterozygote x heterozygote crosses express the lightning bolt tail phenotype suggesting prenatal lethality.
The mutation lightning bolt tail arose spontaneously in a (BALB/cJ x A/J)F1 colony at The Jackson Laboratory in 1998. This line was maintained by sibling inbreeding but eventually required outcrossing for continued survival, so was bred to C57BL/6J. It was then maintained by backcrossing to C57BL/6J at each generation and in 2009 reached generation N5.