Defective FA2H Leads to a Novel Form of Neurodegeneration with Brain Iron Accumulation (NBIA)

Objective: Neurodegeneration with brain iron accumulation (NBIA) represents a distinctive phenotype of neurodegenerative disease for which several causative genes have been identified. The spectrum of neurologic disease associated with mutations in NBIA genes is broad, with phenotypes that range from infantile neurodegeneration and death in childhood to adult-onset parkinsonism-dystonia. Here we report the discovery of a novel gene that leads to a distinct form of NBIA.

Methods: Using autozygosity mapping and candidate gene sequencing, we identified mutations in the fatty acid hydroxylase gene FA2H, newly implicating abnormalities of ceramide metabolism in the pathogenesis of NBIA.

Results: Neuroimaging demonstrated T2 hypointensity in the globus pallidus, confluent T2 white matter hyperintensities, and profound pontocerebellar atrophy in affected members of two families. Phenotypically, affected family members exhibited spastic quadriparesis, ataxia, and dystonia with onset in childhood and episodic neurological decline. Analogous to what has been reported previously for PLA2G6, the phenotypic spectrum of FA2H mutations is diverse based on our findings and those of prior investigators, because FA2H mutations have been identified in both a form of hereditary spastic paraplegia (SPG35) and a progressive familial leukodystrophy.

Interpretation: These findings link white matter degeneration and NBIA for the first time and implicate new signaling pathways in the genesis of NBIA.