Additionally, elevated CSF haptoglobin levels have be seen in idiopathic normal pressure hydrocephalus, traumatic brain injury, Alzheimer's disease, multiple sclerosis, neuromyelitis optica, and Guillain-Barré syndrome [42], [43], [44], [45], [46], and therefore may not be specific to HD. The gene discussed is HP; the disease is early-onset autosomal dominant Alzheimer disease.