Fig. 1

Left panel. Hindlimb clasping score. Het female mice were tested biweekly for the hindlimb clasping reflex and scored on a scale of 0–3 as described in the Methods section. All mice began to show the reflex after week 23. They were then scored over 3 consecutive days, and the results for each mouse were pooled. There was a significant increase in the score in the Het mice (denoted by asterisk, 7.4E−08, Student’s t test). Right upper panel WT mice consistently showed a lack of hindlimb clasping (outward hindlimbs) while the Het mice showed an abnormal response; clasping towards the abdomen (arrow  Right lower panel)