Fig. 2.

Congenital deafness in c-Ret-KI^{Y1062F/Y1062F} mice. (A) Hearing levels (mean ± SE) in 18-d-old c-Ret-KI^{Y1062F/Y1062F} mice (Ret KI^YF/YF, red squares, n = 8) and littermate WT mice (WT, black circles, n = 8) measured by ABR. Significant difference (*P < 0.01) from the control was analyzed by the Mann–Whitney U test. (B) ABR waveforms of 18-d-old littermate WT mice (black line) and c-Ret-KI^YF/YF mice (red line) at 20- to 100-dB SPL at 4 kHz are presented at different scales (WT, 2.0 mV; c-Ret-KI^YF/YF mice, 1.0 mV) for clarity. The peaks of ABR waves I, II, III, and IV are indicated. The absolute latencies of all four ABR waves and the interpeak latencies for waves I–II (auditory nerve) at 100 dB were significantly increased in c-Ret-KI^YF/YF mice as follows: wave I (WT: 1.52 ms vs. c-Ret-KI^YF/YF mice: 3.18 ms), wave II (WT: 2.23 ms vs. c-Ret-KI^YF/YF mice: 4.36 ms), wave III (WT: 3.24 ms vs. c-Ret-KI^YF/YF mice: 5.58 ms), wave IV (WT: 4.86 ms vs. c-Ret-KI^YF/YF mice: 7.43 ms), and waves I–II (WT: 0.82 ms vs. c-Ret-KI^YF/YF mice: 1.21 ms).