Mutations in GLRA1, encoding the GlyR α1 subunit, are the major genetic cause of startle disease/hyperekplexia in humans (Chung et al., 2010; Shiang et al., 1993, 1995) and cause similar disorders in mice (Buckwalter et al., 1994; Holland et al., 2006; Ryan et al., 1994; Traka et al., 2006) and Poll Hereford cattle (Pierce et al., 2001). Here, GLRA1 is linked to hereditary hyperekplexia.