Auditory deficits associated with the frings mgr1 (mass1) mutation in mice

The gene responsible for the audiogenic seizure (AGS) phenotype in Frings mice, which was identified and originally designated Mass1, is now referred to as Mgr1. Although the function of the gene product is not known, the expression pattern suggests a role in the developing CNS. Hearing impairment is often observed in AGS-susceptible rodents and is thought to contribute to the pathology of AGS. We therefore hypothesized that the Frings mouse exhibits early-onset hearing impairment and that the Frings Mgr1 mutation is responsible for the hearing impairment phenotype that leads to the development of AGS susceptibility. Auditory brainstem response (ABR) thresholds were used to evaluate auditory function in mice carrying the Frings Mgr1 allele and were compared with other AGS-susceptible and -resistant mice. ABR testing demonstrated that mice possessing the Frings Mgr1 allele exhibit a mild to moderate level of hearing impairment that is present during the days following hearing onset. Furthermore, the hearing impairment resulting from the Frings Mgr1 allele is relatively stable, which explains the long duration of AGS susceptibility exhibited by Frings mice compared with other AGS-susceptible mice.