S.M., also sometimes referred to as SM-046, is a female patient first described in 1994 who has had exclusive and complete bilateral amygdala destruction since late childhood as a consequence of an extremely rare genetic condition known as Urbach–Wiethe disease. S.M. is notable in that, because of this damage, she has little to no capacity to experience fear or anxiety in her life, a characteristic which has resulted in her being dubbed by the media as the "woman with no fear". S.M. has been studied extensively in scientific research, and has helped researchers to elucidate the function of the amygdala.