To examine whether phenotypic abnormalities result from expression of mutated torsinA or merely represent artefacts, and to establish an appropriate model system for further investigation, the previously characterized tghΔGAGTorAl4 line (line 4), which developed diabetes mellitus by the age of 11 months, was compared to the second transgenic line, namely tghΔGAGTorAl8 (line 8). Here, TOR1A is linked to diabetes mellitus.