A discordant relationship has previously been observed between severity of brain injury and self-reported neuropsychiatric symptoms, with the more mildly brain-injured group reporting the increased severity of neuropsychiatric symptoms.39 Furthermore, injury characteristics of a less severe injury have been found to increase the risk of post-traumatic stress symptoms.40 The inverse relationships seen between GFAP and HRQoL/mental health outcomes in the participants with CT-negative mTBI are, perhaps, biological reflections of this discordance. The gene discussed is GFAP; the disease is injury.