Abnormal neuronal aggregates of alpha-internexin and the three neurofilament (NF) subunits, NFL, NFM, and NFH have recently been identified as the signature lesions of neuronal intermediate filament (IF) inclusion disease (NIFID), a novel neurological disease of early onset with a variable clinical phenotype including frontotemporal dementia, pyramidal and extrapyramidal signs. In other neurodegenerative diseases in which protein aggregates contribute to disease pathogenesis, mutations in the encoding protein cause the hereditary variant of the disease. To determine the molecular genetic contribution to this disease we performed a mutation analysis of all type IV neuronal IF, SOD1 and NUDEL genes in cases of NIFID and unaffected control cases. We found no pathogenic variants.