How does the diagnostic performance of serum glial fibrillary acidic protein (GFAP) and neuronal ubiquitin C-terminal hydrolase (UCH-L1) biomarkers compare with that of validated clinical decision rules for detecting intracranial lesions on computed tomography (CT) of the head in patients with mild traumatic brain injury, and is a combination of biomarkers and clinical decision rules associated with improved performance? This evidence concerns the gene GFAP and brain injury.