Mutations in progranulin gene (GRN) are a common cause of autosomal dominant frontotemporal lobar degeneration and are associated with a wide phenotypic heterogeneity. Here, we describe two probands with behavioral variant frontotemporal dementia with a novel mutation in this gene (1159_1160delTG). Both had a positive family history for dementia and showed atypical features at imaging. Their progranulin plasma levels were undetectable, and the mutation was not present in cDNA, suggesting haploinsufficiency. Progranulin levels were low even in asymptomatic carriers of the variant. Results described enlarge current knowledge on genetic causes of the disease and clinical characteristics of carriers.
Keywords: Deletion; frontotemporal dementia; haploinsufficiency; mutation; progranulin (GRN).