SNP Shot: Genomic Insights

Fatty acid hydroxylase-associated neurodegeneration (FAHN) is a neurodegenerative disease, meaning it causes progressive damage to the nervous system. This condition typically manifests in childhood or adolescence and is marked by difficulties with both movement and vision.

Often, the earliest signs of FAHN involve changes in gait and frequent falls. As the condition progresses, individuals develop significant muscle stiffness (spasticity) and overactive reflexes. Many also experience involuntary muscle cramps (dystonia) and/or problems with coordination and balance (ataxia). These motor impairments worsen over time, potentially leading to the need for wheelchair assistance.

Vision problems are common in FAHN. These arise from the deterioration (atrophy) of the optic nerves, which transmit visual information to the brain, as well as from issues affecting the muscles controlling eye movement. Consequently, individuals may experience reduced visual acuity, a narrowed field of vision, impaired color vision, misaligned eyes (strabismus), involuntary rapid eye movements (nystagmus), or difficulty intentionally moving their eyes (supranuclear gaze palsy).

FAHN can also cause speech difficulties (dysarthria), and some severely affected individuals eventually lose the ability to speak. Chewing and swallowing problems (dysphagia) are also common. In severe instances, this can lead to malnutrition and the need for a feeding tube. Swallowing difficulties can also result in aspiration pneumonia, a potentially life-threatening bacterial lung infection. As the disease advances, some individuals may experience seizures and a decline in cognitive abilities.

Brain MRI scans of individuals with FAHN often reveal iron accumulation, particularly in the globus pallidus, a brain region crucial for movement regulation. Similar iron accumulation patterns are observed in other neurological disorders, such as infantile neuroaxonal dystrophy and pantothenate kinase-associated neurodegeneration. These disorders, including FAHN, are classified as neurodegeneration with brain iron accumulation (NBIA).

Inheritance:

FAHN is inherited in an autosomal recessive manner. This means that an individual must inherit two copies of the mutated gene, one from each parent, to develop the condition. The parents, who each carry only one copy of the mutated gene, are typically asymptomatic carriers.