NEFL Gene

NEFL Gene

<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">NEFL Gene</th>
</tr>
<tr>
<td class="label">Symbol</td>
<td>NEFL</td>
</tr>
<tr>
<td class="label">Full Name</td>
<td>Neurofilament Light Polypeptide</td>
</tr>
<tr>
<td class="label">Chromosomal Location</td>
<td>8p21.2</td>
</tr>
<tr>
<td class="label">NCBI Gene ID</td>
<td>4747</td>
</tr>
<tr>
<td class="label">OMIM ID</td>
<td>162280</td>
</tr>
<tr>
<td class="label">Ensembl ID</td>
<td>ENSG00000104825</td>
</tr>
<tr>
<td class="label">UniProt ID</td>
<td>P07196</td>
</tr>
<tr>
<td class="label">Protein Length</td>
<td>543 amino acids</td>
</tr>
<tr>
<td class="label">Molecular Weight</td>
<td>~61.5 kDa</td>
</tr>
<tr>
<td class="label">Expression</td>
<td>CNS and PNS neurons (axons)</td>
</tr>
<tr>
<td class="label">Associated Diseases</td>
<td>ALS, CMT, AD, PD, MS, FTD, Huntington's</td>
</tr>
<tr>
<td class="label">Subunit</td>
<td>Gene</td>
</tr>
<tr>
<td class="label">NFL (Light)</td>
<td>NEFL</td>
</tr>
<tr>
<td class="label">NFM (Medium)</td>
<td>NEFM</td>
</tr>
<tr>
<td class="label">NFH (Heavy)</td>
<td>NEFH</td>
</tr>
<tr>
<td class="label">Method</td>
<td>Sample</td>
</tr>
<tr>
<td class="label">Simoa (Single molecule array)</td>
<td>Blood, CSF</td>
</tr>
<tr>
<td class="label">ELISA</td>

NEFL Gene

<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">NEFL Gene</th>
</tr>
<tr>
<td class="label">Symbol</td>
<td>NEFL</td>
</tr>
<tr>
<td class="label">Full Name</td>
<td>Neurofilament Light Polypeptide</td>
</tr>
<tr>
<td class="label">Chromosomal Location</td>
<td>8p21.2</td>
</tr>
<tr>
<td class="label">NCBI Gene ID</td>
<td>4747</td>
</tr>
<tr>
<td class="label">OMIM ID</td>
<td>162280</td>
</tr>
<tr>
<td class="label">Ensembl ID</td>
<td>ENSG00000104825</td>
</tr>
<tr>
<td class="label">UniProt ID</td>
<td>P07196</td>
</tr>
<tr>
<td class="label">Protein Length</td>
<td>543 amino acids</td>
</tr>
<tr>
<td class="label">Molecular Weight</td>
<td>~61.5 kDa</td>
</tr>
<tr>
<td class="label">Expression</td>
<td>CNS and PNS neurons (axons)</td>
</tr>
<tr>
<td class="label">Associated Diseases</td>
<td>ALS, CMT, AD, PD, MS, FTD, Huntington's</td>
</tr>
<tr>
<td class="label">Subunit</td>
<td>Gene</td>
</tr>
<tr>
<td class="label">NFL (Light)</td>
<td>NEFL</td>
</tr>
<tr>
<td class="label">NFM (Medium)</td>
<td>NEFM</td>
</tr>
<tr>
<td class="label">NFH (Heavy)</td>
<td>NEFH</td>
</tr>
<tr>
<td class="label">Method</td>
<td>Sample</td>
</tr>
<tr>
<td class="label">Simoa (Single molecule array)</td>
<td>Blood, CSF</td>
</tr>
<tr>
<td class="label">ELISA</td>
<td>Blood, CSF</td>
</tr>
<tr>
<td class="label">Electrochemiluminescence</td>
<td>Blood, CSF</td>
</tr>
<tr>
<td class="label">Lumipulse</td>
<td>CSF</td>
</tr>
<tr>
<td class="label">Population</td>
<td>Serum NfL (pg/mL)</td>
</tr>
<tr>
<td class="label">Young adults (<40)</td>
<td>3-12</td>
</tr>
<tr>
<td class="label">Middle age (40-60)</td>
<td>8-25</td>
</tr>
<tr>
<td class="label">Elderly (>60)</td>
<td>12-40</td>
</tr>
<tr>
<td class="label">ALS patients</td>
<td>50-300</td>
</tr>
<tr>
<td class="label">AD patients</td>
<td>15-60</td>
</tr>
<tr>
<td class="label">Trial</td>
<td>Indication</td>
</tr>
<tr>
<td class="label">Pharmatherapeutics</td>
<td>ALS</td>
</tr>
<tr>
<td class="label">TPN-101</td>
<td>ALS/FTD</td>
</tr>
<tr>
<td class="label">Reldesemtiv</td>
<td>ALS</td>
</tr>
</table>

NEFL (Neurofilament Light Polypeptide) encodes the light chain subunit of neurofilaments, the most abundant intermediate filament in [neurons](/entities/neurons) of the central and peripheral nervous systems. Neurofilaments are essential for maintaining axonal caliber, supporting myelinated axons, and enabling rapid nerve conduction. NEFL is also one of the most extensively studied biomarkers for neurodegenerative diseases, with blood and CSF neurofilament light chain (NfL) levels reflecting the degree of axonal injury across Alzheimer's disease, Parkinson's disease, ALS, and numerous other neurological conditions[@neurofilament2017][@neurofilament2018].

Overview

Gene Structure and Expression

Genomic Organization

The NEFL gene spans approximately 11.5 kb on chromosome 8p21.2 and contains 4 exons. The gene encodes a single polypeptide that is expressed predominantly in neurons during late embryonic and postnatal development, with expression maintained throughout adult life[@nefl_structure].

Expression Pattern

NEFL is expressed in[@neurofilament2017][@blood2018]:

• Central nervous system: Large pyramidal neurons of the cortex, motor neurons of the spinal cord, Purkinje cells of the cerebellum, retinal ganglion cells, dopaminergic neurons of the substantia nigra
• Peripheral nervous system: Large myelinated fibers of peripheral nerves, sensory and motor neurons
• Non-neuronal: Low or absent expression in glia, non-neural tissues

Protein Structure

Neurofilament Architecture

Neurofilaments are assembled from three subunits in a heteropolymer structure[@nefl_structure]:

NFL serves as the structural backbone, with NFM and NFH assembling along NFL tetramers to form the mature filament. Each neurofilament is approximately 10 nm in diameter and can extend to many micrometers within axons.

Domain Structure

The NEFL protein consists of three domains[@nefl_structure]:

Phosphorylation of the tail domain regulates neurofilament spacing in axons, affecting axonal caliber.

Assembly Pathway

Neurofilament assembly follows this pathway[@nefl_structure]:

Normal Physiological Function

Axonal Cytoskeleton

Neurofilaments provide structural support and maintain axonal caliber[@nefl_structure]:

• Mechanical support: Resists compressive and tensile forces on axons
• Axonal diameter regulation: Neurofilament content directly determines axonal diameter (larger axons = more neurofilaments)
• Myelin attachment: Neurofilament-filled axons provide the scaffold for myelin wrapping by Schwann cells (PNS) or oligodendrocytes (CNS)
• Fast axonal transport support: Neurofilaments interact with motors for organelle transport

Nerve Conduction Velocity

Axonal caliber, maintained by neurofilaments, directly determines nerve conduction velocity[@nefl_structure]:

• Large-diameter myelinated axons conduct at 40-120 m/s
• Small unmyelinated fibers conduct at 0.5-2 m/s
• NEFL mutations causing smaller axonal caliber → slowed conduction → neuropathy

Neuronal Development

During development, neurofilament expression supports[@nefl_structure]:

• Axon growth and pathfinding
• Synapse formation and maintenance
• Dendritic arborization
• Neuronal survival

Disease Associations

Amyotrophic Lateral Sclerosis (ALS)

NfL is one of the most extensively validated biomarkers for ALS[@neurofilament2017][@blood2018]:

• Diagnostic biomarker: Elevated NfL in CSF (mean ~3,500 pg/mL vs ~600 pg/mL in controls) and blood
• Prognostic marker: Higher NfL levels correlate with faster disease progression and shorter survival
• Biomarker for clinical trials: Used as endpoint to measure treatment effects on neurodegeneration rate
• Disease progression tracking: NfL levels increase over time as motor neurons die
• Differential diagnosis: Helps distinguish ALS from mimics (e.g., multifocal motor neuropathy)
• Genetics: Rare NEFL mutations cause ALS with typical TDP-43 pathology

Charcot-Marie-Tooth Disease (CMT)

NEFL mutations cause autosomal dominant intermediate CMT[@nefl2002][@cmt_nefl]:

• CMT type 1F (NF-L): Intermediate or predominantly demyelinating phenotype
• CMT type 2E (NF-L): Predominantly axonal neuropathy
• Clinical features: Distal weakness, sensory loss, foot deformities, slowed nerve conduction
• Pathology: Reduced axonal caliber, loss of large myelinated fibers, neurofilament accumulation
• Mechanism: Mutations disrupt neurofilament assembly and axonal transport
• Genotype-phenotype: Over 50 pathogenic variants described (missense, nonsense, splice site)

Alzheimer's Disease

NfL is elevated in AD and reflects the axonal injury component of the disease[@neurofilament2018][@nefl_frontotemporal]:

• Diagnostic value: NfL in CSF (mean ~400 pg/mL in AD vs ~200 pg/mL controls)
• Progression marker: Higher NfL correlates with faster cognitive decline and brain atrophy
• Cognitive correlation: NfL levels predict rate of MMSE decline
• Braak stage correlation: NfL elevation tracks with neurofibrillary tangle burden
• Comparison to other markers: NfL rises later than p-tau181/217 but before clinical symptoms in some cases
• Interaction with tau: NfL and p-tau provide complementary information about neurodegeneration vs tangle pathology

Parkinson's Disease

NfL serves as a biomarker of nigrostriatal degeneration in PD[@nefl_parkinson]:

• Diagnostic utility: Elevated serum NfL in PD vs controls (mean ~20 pg/mL vs ~12 pg/mL)
• Progression marker: Higher NfL correlates with worse UPDRS scores and faster progression
• Atypical PD differentiation: Much higher NfL in PSP and MSA vs typical PD
• Substantia nigra involvement: Reflects dopaminergic neuron loss in the SNc
• Prodromal potential: Elevated NfL may detect axonal injury before motor diagnosis
• Comparison to alpha-synuclein: NfL and alpha-synuclein seed amplification provide complementary information

Multiple Sclerosis

NfL is widely used as a biomarker in MS[@nefl_ms]:

• Disease activity marker: Elevated NfL during active relapses and in progressive MS
• Treatment monitoring: NfL levels decrease with effective immunomodulatory therapy
• Prognostic value: Higher baseline NfL predicts worse long-term outcomes
• Conversion prediction: NfL helps predict CIS to clinically definite MS conversion
• Dark visible lesions: NfL elevation reflects the acute axonal injury visible as black holes on MRI

Frontotemporal Dementia and Other Dementias

NfL elevation across dementia spectrum[@nefl_frontotemporal]:

• FTD subtypes: Elevated in behavioral variant FTD, semantic variant PPA, progressive supranuclear palsy, corticobasal syndrome
• AD vs FTD differentiation: NfL generally higher in FTD than AD, complements tau markers
• Progression rate: Higher NfL predicts faster clinical decline in FTD
• ALS-FTD overlap: Very high NfL in patients with both motor and cognitive symptoms

Neurofilament as Biomarker

Measurement Methods

Normal Reference Ranges

Clinical Utility

NfL biomarker applications[@neurofilament2017][@blood2018][@nefl_ms]:

Limitations and Caveats

• Age dependence: NfL increases with age, requiring age-adjusted thresholds
• Non-specific: Elevated NfL reflects axonal injury from any cause (trauma, stroke, infection)
• Variable kinetics: Different diseases release NfL at different rates
• Kidney function: NfL is cleared by the kidney; renal impairment elevates serum NfL
• Longitudinal variability: Single measurements may not reflect disease trajectory

Therapeutic Implications

Neuroprotective Strategies

Approaches to protect neurons from NfL-related pathology[@neurofilament2017][@nefl2019]:

• TDP-43 modulators: Target upstream events causing neurofilament accumulation in ALS
• Axonal transport enhancers: Improve delivery of neurofilaments and organelles along axons
• Neuroinflammation reduction: Lower microglial activation to reduce secondary axonal injury
• Anti-aggregation agents: Prevent toxic neurofilament aggregates from forming

Clinical Trials Using NfL as Endpoint

Animal Models

NEFL Knockout Mice

• Axonal atrophy: Reduced axonal caliber without neurofilament content
• Slowed conduction: Reduced nerve conduction velocity
• Surprisingly mild phenotype: Mice survive and breed despite major structural deficits
• Compensatory upregulation: Other cytoskeletal proteins (tau, actin) upregulated

NEFL Mutant Mice (Swaying, Nf^Lnl)

• Late-onset ataxia: Progressive gait instability resembling CMT
• Axonal pathology: Accumulation and aggregation of mutant neurofilaments
• Demyelination secondary: Myelin degeneration secondary to axonal defects
• Models human disease: Recapitulates key features of NEFL-associated neuropathy

Research Directions

Key areas of ongoing research include[@neurofilament2017][@blood2018]:

• Fluid biomarker combinations: NfL combined with p-tau217, GFAP, NfH for improved accuracy
• Blood-based neurofilament assays: Development of point-of-care testing for clinical use
• Neurofilament heavy chain (NfH): Complementary biomarker with potentially different kinetics
• Age-adjusted reference values: Establishing population norms across age groups
• Treatment response monitoring: Using NfL to guide therapeutic decisions in real time
• Genetic forms of ALS/CMT: Understanding how NEFL mutations cause disease

Summary

NEFL encodes the light chain of neurofilaments, the primary cytoskeletal protein of axons. Neurofilament maintenance is essential for axonal caliber and nerve conduction velocity, and disruption of NEFL causes Charcot-Marie-Tooth disease. When neurons die in neurodegenerative diseases, neurofilament light chain is released into biological fluids, making NfL one of the most valuable biomarkers for ALS, Alzheimer's disease, Parkinson's disease, MS, FTD, and other neurological conditions. Blood NfL testing is now widely used in clinical trials and is moving toward clinical practice, offering a window into the degree of ongoing axonal injury in real time.

See Also

• [Neurofilament Light Chain Biomarker](/biomarkers/neurofilament-light-chain-nfl)
• [ALS Disease Mechanisms](/diseases/amyotrophic-lateral-sclerosis)
• [Alzheimer's Disease Biomarkers](/biomarkers/alzheimers-disease-biomarkers)
• [Parkinson's Disease Biomarkers](/biomarkers/parkinsons-disease-biomarkers)
• [Charcot-Marie-Tooth Disease](/diseases/charcot-marie-tooth)
• [Axonal Transport](/mechanisms/axonal-transport)
• [Cytoskeletal Dysfunction](/mechanisms/cytoskeletal-dysfunction)

External Links

• [NEFL - NCBI Gene](https://www.ncbi.nlm.nih.gov/gene/4747)
• [NEFL Protein - UniProt](https://www.uniprot.org/uniprot/P07196)
• [NEFL - GeneCards](https://www.genecards.org/cgi-bin/carddisp.pl?gene=NEFL)
• [OMIM: 162280](https://www.omim.org/entry/162280)
• [Ensembl: ENSG00000104825](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000104825)

Pathway Context

Related Hypotheses

From the [SciDEX Exchange](/exchange) — scored by multi-agent debate

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• [Blood-Brain Barrier SPM Shuttle System](/hypothesis/h-959a4677) — <span style="color:#81c784;font-weight:600">0.75</span> · Target: TFRC
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• [Targeting Bacterial Curli Fibrils to Prevent α-Synuclein Cross-Seeding](/hypothesis/h-8b7727c1) — <span style="color:#81c784;font-weight:600">0.64</span> · Target: CSGA

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• [Neuroinflammation resolution mechanisms and pro-resolving mediators](/analysis/SDA-2026-04-01-gap-014) &#x1f504;
• [What are the mechanisms by which gut microbiome dysbiosis influences Parkinson&#x27;s disease pathogenesi](/analysis/SDA-2026-04-01-gap-20260401-225149) &#x1f504;
• [What are the mechanisms by which gut microbiome dysbiosis influences Parkinson&#x27;s disease pathogenesi](/analysis/SDA-2026-04-01-gap-20260401-225155) &#x1f504;

Pathway Diagram

The following diagram shows the key molecular relationships involving NEFL Gene discovered through SciDEX knowledge graph analysis: