The human cDNA was engineered with a c.1077G>A point mutation, resulting in codon 315 changing from alanine to threonine (p.A315T or p.Ala315Thr). This mutation is associated with familial amyotrophic lateral sclerosis (ALS) in humans. A construct comprising the tetracycline inducible tetO promoter, the human cDNA and an SV40 poly signal, was injected into the pronuclei of fertilized C57BL/6 oocytes. Two lines, this line and numbers 13, were selected for further study.