Table 1.

Proteins and markers that demonstrate possible correlations with disease duration from initial biomarker discovery efforts.

Protein	Details	Ref.
Cerebrospinal fuid
Glial-derived neurotrophic factor	Elevated in ALS but no change observed between before and 6 weeks after taking riluzole	[49]
VEGF	Positive correlation between VEGF and hypoxemia in ALS; an opposite correlation in hypoxemic neurological control	[53]
Erythropoietin	Low erythropoietin levels are associated with rapid progression of disease	[54]
VgF	Reduced levels of full-length VgF correlate with decreased muscle weakness	[55]
Tau	Reductions in levels observed in ALS patients taking memantine and riluzole during a clinical drug trial	[6]
Phosphorylated neuroflament heavy chain	Reductions in levels observed in ALS patients taking memantine and riluzole during a clinical drug trial	[6]
	Higher levels are also observed in those with more rapid disease progression and those with predominantly upper motor neuron signs	[60]
Neuroflament light chain	Higher levels are associated with a more rapid disease progression	[61]
Prostaglandin	No benefcial effect seen during clinical drug trial with celecoxib	[51]
Macrophage chemoattractant protein-1	Higher levels are apparent in those with shorter survival	[57]
Substance P	Elevated in cerebrospinal fuid particularly when disease duration is <2.5 years	[58]
Transglutaminase	Higher levels are observed in the early stages compared with lower levels in the later stages	[59]
Blood
Fibronectin	Negative correlation with duration of disease	[62]
Hyaluronic acid	Positive correlation with duration of disease	[63]
IL-6	Positive correlation with duration of disease	[64]
T cells	Positive correlation with duration of disease	[65]
TGF-β1	Positive correlation with duration of disease	[66]
IGF	High levels more prominent in those with long survival times	[67]
Urine
8-oxo-deguanosine	Positive correlation with disease severity	[68]
Glucosylgalactosyl hydroxylysine (Glu–Gal–Hyl)	Negative correlation with duration of disease	[64]

ALS: Amyotrophic lateral sclerosis.