Frequency of progranulin mutations in a German cohort of 79 frontotemporal dementia patients.

Mutations of the progranulin gene lead to progranulin haploinsufficiency and to frontotemporal lobar degeneration (FTD) with TDP-43 positive inclusions. It is assumed that unknown genetic, epigenetic and environmental factors are responsible for the observed marked degree of phenotypic variability among mutation carriers. This is the first published series of German FTD cases screened for progranulin mutations. Mean age at onset was 62 years, 19 patients (24%) had a positive family history of dementia, and 11 patients (14%) had a positive family history for probable FTD. Data on FTD subtypes are presented. Two mutations were identified (3%), one of which has been described previously. Clinically, both patients showed the frontal-behavioural variant type of FTD. Remarkably, a sibling of one case presented with progressive nonfluent aphasia, clinically distinct from the brother. We also performed quantitative PCR analyses to detect potential whole progranulin gene and exon deletions. Here, results were negative.