FA2H-Associated Neurodegeneration Pathway

FA2H-Associated Neurodegeneration Pathway

Overview

FA2H (Fatty Acid 2-Hydroxylase) encodes an enzyme essential for the synthesis of 2-hydroxylated fatty acids, which are critical components of myelin sheath lipids. Mutations in FA2H cause a spectrum of neurodegenerative disorders including neurodegeneration with brain iron accumulation (NBIA), hereditary spastic paraplegia (HSP), and leukodystrophies. PMID: 31471313

Gene and Protein

FA2H Gene

| Attribute | Value |
|-----------|-------|
| Gene Symbol | FA2H |
| Chromosomal Location | Chromosome 16q23.1 |
| Gene Length | ~13 kb |
| Exons | 14 exons |
| Protein | Fatty Acid 2-Hydroxylase |
| Subcellular Location | Endoplasmic reticulum membrane |

Protein Function

FA2H catalyzes the 2-hydroxylation of fatty acids, primarily very-long-chain fatty acids (VLCFAs), in the endoplasmic reticulum. This modification is essential for:

• Myelin sheath lipid composition
• Membrane fluidity
• Cellular signaling

Disease Associations

NBIA Subtype (FA2H-NBIA)

FA2H mutations account for approximately 5-10% of NBIA cases, characterized by:

• Iron accumulation in the globus pallidus
• Progressive motor dysfunction
• Developmental regression
• Seizures in some patients

Hereditary Spastic Paraplegia (SPG35)

FA2H mutations cause an autosomal recessive form of complicated HSP:

• Spastic paraplegia
• Dysarthria
• Cognitive decline
• Optical atrophy

Leukodystrophy

FA2H-Associated Neurodegeneration Pathway

Overview

FA2H (Fatty Acid 2-Hydroxylase) encodes an enzyme essential for the synthesis of 2-hydroxylated fatty acids, which are critical components of myelin sheath lipids. Mutations in FA2H cause a spectrum of neurodegenerative disorders including neurodegeneration with brain iron accumulation (NBIA), hereditary spastic paraplegia (HSP), and leukodystrophies. PMID: 31471313

Gene and Protein

FA2H Gene

| Attribute | Value |
|-----------|-------|
| Gene Symbol | FA2H |
| Chromosomal Location | Chromosome 16q23.1 |
| Gene Length | ~13 kb |
| Exons | 14 exons |
| Protein | Fatty Acid 2-Hydroxylase |
| Subcellular Location | Endoplasmic reticulum membrane |

Protein Function

FA2H catalyzes the 2-hydroxylation of fatty acids, primarily very-long-chain fatty acids (VLCFAs), in the endoplasmic reticulum. This modification is essential for:

• Myelin sheath lipid composition
• Membrane fluidity
• Cellular signaling

Disease Associations

NBIA Subtype (FA2H-NBIA)

FA2H mutations account for approximately 5-10% of NBIA cases, characterized by:

• Iron accumulation in the globus pallidus
• Progressive motor dysfunction
• Developmental regression
• Seizures in some patients

Hereditary Spastic Paraplegia (SPG35)

FA2H mutations cause an autosomal recessive form of complicated HSP:

• Spastic paraplegia
• Dysarthria
• Cognitive decline
• Optical atrophy

Leukodystrophy

FA2H-related white matter disease features:

• Diffuse cerebral white matter abnormalities
• Demyelination
• Progressive neurological deterioration

Pathway Diagram

Molecular Mechanisms

Myelin Dysfunction

FA2H deficiency leads to:

• Reduced 2-hydroxylated sphingolipids in myelin
• Impaired myelin sheath stability
• Increased susceptibility to oxidative damage
• Progressive demyelination

Iron Accumulation

The mechanism linking FA2H to iron accumulation involves:

• Dysregulation of iron transport proteins
• Altered lipid metabolism affecting iron sequestration
• Increased oxidative stress promoting iron deposition

Therapeutic Targets

Emerging Strategies:

• Gene therapy to restore FA2H expression
• Small molecule FA2H activators
• Iron chelation therapy for symptomatic management
• Myelin stabilization approaches

Clinical Features

| Feature | NBIA (FA2H) | SPG35 | Leukodystrophy |
|---------|-------------|-------|----------------|
| Onset | Childhood | Childhood | Early adulthood |
| Motor symptoms | +++ | +++ | ++ |
| Cognitive decline | ++ | + | ++ |
| Iron deposition | +++ | - | - |
| White matter changes | ++ | ++ | +++ |

Genetics

• Inheritance: Autosomal recessive
• Variants: Missense, nonsense, splice-site
• Population: Rare (<1:1,000,000)

See Also

• [NBIA Overview](/diseases/neurodegeneration-with-brain-iron-accumulation)
• [PKAN Pathway](/mechanisms/pkan-neurodegeneration-pathway)
• [Pantothenate Kinase](/genes/pank2)
• [Iron Homeostasis](/mechanisms/metal-homeostasis-neurodegeneration)
• [Myelin Disorders](/mechanisms/demyelination-pathway)

External Links

• [OMIM - FA2H](https://www.omim.org/entry/614609)
• [GeneCards - FA2H](https://www.genecards.org/cgi-bin/carddisp.pl?gene=FA2H)
• [NBIA Spectrum](https://www.nbiausa.org/)

References