Normally, S100β is not detectable in serum and its elevation has been associated with neurological damage and diseases, such as ischemic and hemorrhagic stroke, aneurysmal subarachnoid hemorrhage, Alzheimer’s disease, frontotemporal dementia, Down’s syndrome, epilepsy, sleep apnea syndrome, and melanoma [137, 138]. The gene discussed is S100B; the disease is early-onset autosomal dominant Alzheimer disease.