Clinical onset and progression of disease. Weight loss and limb motor abnormalities in hmSOD1 transgenic rats as a function of age. (A) Weight in grams of male hmSOD1 (black) and wild-type littermates (gray). (B) Weight expressed as percent of maximum recorded weight in male (black) and female (gray) hmSOD1 rats. (C) Limb paralysis motor score of male (black) and female (gray) hmSOD1 rats. See Table 1 for scoring criteria. (D) Average time between age of onset for weight loss and limb paralysis relative to disease end-stage in hmSOD1 rats. *, significantly different (P < 0.01, paired T test).