Gpr56 mutants display neuropathy-like symptoms. (A and B) IHC on teased nerve fibers from WT (n = 3) and Gpr56^−/− (n = 4) mouse SNs on P21 stained for Pan-NaV to mark nodes of Ranvier (arrowheads). Bar, 50 µm. (C) Quantification of internode length on P21 (P < 0.05, one-way ANOVA). (D and E) Hindlimb clasping observed in Gpr56 mutants (n = 8/11) but not WT siblings on P180 (n = 1/11). (F and G) Quantification of time on rotarod to assess sensorimotor control on P180 (genotype effect: ***, P < 0.001, two-way ANOVA; n = 11 WT, n = 16 Gpr56^+/−, n = 13 Gpr56^−/−) and P300 (genotype effect, *, P < 0.02, two-way ANOVA; n = 10 WT, n = 15 Gpr56^+/−, n = 12 Gpr56^−/−). Error bars represent SEM. (H) Quantification of EMG latency (m/s) in animals aged P200–P300 (***, P < 0.001, one-way ANOVA). Error bars represent SD. (I) Quantification of EMG response velocity (m/s) in animals aged P200–P300 (***, P < 0.001, one-way ANOVA). Error bars represent SD. (J) Representative traces from EMG recordings from WT (black, n = 5), Gpr56^+/− (blue, n = 12), and Gpr56^−/− (red, n = 11) SNs. Arrows denote the point of the first positive deflection.