SYT1 and early-onset autosomal dominant Alzheimer disease: The fact that synaptic loss is the main pathological feature of dementia due to Alzheimer’s disease that correlates with cognitive decline, together with the notion that synaptotagmin-1 is directly involved in the regulation of neurotransmitter release [16, 18], make synaptotagmin-1 a potential CSF biomarker to follow progression of clinical symptoms.