Definite Behavioral Variant of Frontotemporal Dementia with C9ORF72 Expansions Despite Positive Alzheimer's Disease Cerebrospinal Fluid Biomarkers

Hexanucleotide expansion repeats in the C9ORF72 gene are a major cause of familial and, to a lesser extent, sporadic frontotemporal lobar degeneration (FTLD), amyotrophic lateral sclerosis (ALS), and FTLD-ALS. To examine whether C9ORF72 expansions co