Table 3

Markers of synaptic and neurotransmitter function

Fluid biomarkersBiological functionUnspecified FTDPSPGRNC9orf72MAPTRef.
SNAP-25Vesicle fusion and release of neurotransmitters 65
SynaptotagminCa2+ sensor triggering vesicle fusion on calcium influx 65 66
SynaptophysinSynaptic vesicle protein that regulates SNARE assembly and vesicle fusion 66
GAP-43Ca2+-dependent vesicle fusion 66
Synapsin 1Vesicle trafficking 66
NeurograninLong-term potentiation and synaptic plasticity and regulates intracellular Ca2+ concentration 65 66
SynaptopodinRegulates intracellular Ca2+ concentration 66
ReelinRegulation of filopodia formation, dendrite growth and spine formation, and synaptogenesis, modulation of synaptic plasticity and neurotransmitter release 68
NPTXROrganisation of excitatory and inhibitory synapses 69
NPTX2Modulation of strength of excitatory synapses 69
DANeurotransmitter 71
DOPACDA metabolite 71
  • Blue, in cerebrospinal fluid; green, in blood and cerebrospinal fluid; red, in blood; yellow, in neuron-derived exosomes from plasma.

  • – indicates (unchanged levels); ↑ indicates increased levels; ↓ indicates decreased levels; all compared with controls.

  • C9orf72, chromosome 9 open reading frame 72; DA, dopamine; DOPAC, 3,4-dihydroxyphenylacetic acid; FTD, frontotemporal dementia; GAP-43, growth associated protein, 43 kDa; GRN, progranulin; MAPT, microtubule-associated protein tau; NPTX2, neuronal pentraxin-2; NPTXR, neuronal pentraxin receptor; P, presymptomatic; PSP, progressive supranuclear palsy; Ref, reference; S, symptomatic; SNAP-25, synaptosomal-associated protein, 25 kDa; SNARE, soluble NSF attachment protein receptor.