Mitochondrial membrane protein-associated neurodegeneration (MPAN)

Neurodegeneration with brain iron accumulation (NBIA) is a group of rare and devastating disorders characterized by iron deposition in the brain. Mutations in C19orf12 cause autosomal recessive inherited mitochondrial membrane protein-associated neurodegeneration (MPAN), which may account for up to 30% of NBIA cases. The C19orf12 gene product is an orphan mitochondrial membrane protein, and most mutations are predicted to cause loss of function. From 67 MPAN cases so far reported, we describe here the clinical, radiological, and genetic features. Key clinical features are pyramidal and extrapyramidal signs, cognitive decline, neuropsychiatric abnormalities, optic atrophy, and motor axonal neuropathy. Magnetic resonance imaging shows the eponymous brain iron accumulation in globus pallidus and substantia nigra and in some cases a hyperintense streaking of the medial medullary lamina. The latter sign may discriminate MPAN from other NBIA subtypes. In two postmortem MPAN cases, neuropathology showed axonal spheroids, Lewy bodies, and hyperphosphorylated tau-containing inclusions.