The disease currently known as frontotemporal dementia (FTD) has undergone a complex evolution from its first description by Arnold Pick and later by Alois Alzheimer, through the first clinicopathological criteria introduced by David Neary and David Mann, to its current nomenclatural perception as a complex clinicopathological entity. Currently, Frontotemporal lobar degeneration is viewed as a heterogeneous syndrome caused by progressive degeneration of the frontal and temporal lobes of the brain. Clinically, it can manifest as three syndromes of frontotemporal dementia (behavioral variant of FTD, progressive non-fluent aphasia and semantic dementia) but also as so-called "overlap" syndromes involving corticobasal degeneration and progressive supranuclear palsy. Its prevalence is about 10 % among all dementias and 40 % among dementias with onset between 45 and 65 years of age. The clinical manifestation of the different subtypes varies, the common denominator being behavioral disturbances and impairment of fatic, gnostic and executive functions. Mnestic and visuo-spatial functions, although preserved for a relatively long time, are superimposed by personality disintegration, fatic, gnostic and executive dysfunction. Compared with Alzheimer's disease, it generally has an earlier age of onset, a more rapid course and more devastating impairment of individual cognitive domains. FTD has a heritability of more than 30 % according to current knowledge. The main genes involved are MAPT, C9orf72 and GRN. More rarely affected genes are VCP, TDP-43, FUS and CHMP2B. In our article, we focus on the genetics of FTD and the clinic-genetic-pathological correlations. We also aim to provide a plastic picture of how individual mutations affect the molecular mechanisms of neurodegeneration.

• MeSH
• Epigenesis, Genetic genetics   MeSH
• Frontotemporal Dementia * diagnosis   genetics   classification   MeSH
• Genetic Testing methods   MeSH
• Humans MeSH
• Primary Progressive Nonfluent Aphasia diagnosis   genetics   MeSH
• Progranulins genetics   MeSH
• tau Proteins genetics   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Review MeSH

BACKGROUND: Pathogenic heterozygous mutations in the progranulin gene (GRN) are a key cause of frontotemporal dementia (FTD), leading to significantly reduced biofluid concentrations of the progranulin protein (PGRN). This has led to a number of ongoing therapeutic trials aiming to treat this form of FTD by increasing PGRN levels in mutation carriers. However, we currently lack a complete understanding of factors that affect PGRN levels and potential variation in measurement methods. Here, we aimed to address this gap in knowledge by systematically reviewing published literature on biofluid PGRN concentrations. METHODS: Published data including biofluid PGRN concentration, age, sex, diagnosis and GRN mutation were collected for 7071 individuals from 75 publications. The majority of analyses (72%) had focused on plasma PGRN concentrations, with many of these (56%) measured with a single assay type (Adipogen) and so the influence of mutation type, age at onset, sex, and diagnosis were investigated in this subset of the data. RESULTS: We established a plasma PGRN concentration cut-off between pathogenic mutation carriers and non-carriers of 74.8 ng/mL using the Adipogen assay based on 3301 individuals, with a CSF concentration cut-off of 3.43 ng/mL. Plasma PGRN concentration varied by GRN mutation type as well as by clinical diagnosis in those without a GRN mutation. Plasma PGRN concentration was significantly higher in women than men in GRN mutation carriers (p = 0.007) with a trend in non-carriers (p = 0.062), and there was a significant but weak positive correlation with age in both GRN mutation carriers and non-carriers. No significant association was seen with weight or with TMEM106B rs1990622 genotype. However, higher plasma PGRN levels were seen in those with the GRN rs5848 CC genotype in both GRN mutation carriers and non-carriers. CONCLUSIONS: These results further support the usefulness of PGRN concentration for the identification of the large majority of pathogenic mutations in the GRN gene. Furthermore, these results highlight the importance of considering additional factors, such as mutation type, sex and age when interpreting PGRN concentrations. This will be particularly important as we enter the era of trials for progranulin-associated FTD.

• MeSH
• Frontotemporal Dementia * genetics   pathology   MeSH
• Humans MeSH
• Membrane Proteins genetics   MeSH
• Intercellular Signaling Peptides and Proteins genetics   MeSH
• Mutation genetics   MeSH
• Progranulins genetics   MeSH
• Nerve Tissue Proteins genetics   MeSH
• Virulence MeSH
• Check Tag
• Humans MeSH
• Male MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Systematic Review MeSH

Various proteins play a decisive role in the pathology of different neurodegenerative diseases. Nonetheless, most of these proteins can only be detected during a neuropathological assessment, although some non-specific biomarkers are routinely tested for in the cerebrospinal fluid (CSF) as a part of the differential diagnosis of dementia. In antemortem CSF samples from 117 patients with different types of neuropathologically confirmed neurodegenerative disease with dementia, we assessed total-tau (t-tau), phosphorylated-tau (181P) (p-tau), amyloid-beta (1-42) (Aβ42), TAR DNA binding protein (TDP)-43, progranulin (PGRN), and neurofilament light (NfL) chain levels, and positivity of protein 14-3-3. We found t-tau levels and the t-tau/p-tau ratios were significantly higher in prion diseases compared to the other neurodegenerative diseases. Statistically significant differences in the t-tau/Aβ42 ratio predominantly corresponded to t-tau levels in prion diseases and Aβ42 levels in AD. TDP-43 levels were significantly lower in prion diseases. Additionally, the TDP-43/Aβ42 ratio was better able to distinguish Alzheimer's disease from other neurodegenerative diseases compared to using Aβ42 alone. In frontotemporal lobar degeneration, PRGN levels were significantly higher in comparison to other neurodegenerative diseases. There is an increasing need for biomarkers suitable for diagnostic workups for neurodegenerative diseases. It appears that adding TDP-43 and PGRN to the testing panel for neurodegenerative diseases could improve the resolution of differential diagnoses.

• MeSH
• Amyloid beta-Peptides cerebrospinal fluid   MeSH
• Biomarkers cerebrospinal fluid   MeSH
• Dementia cerebrospinal fluid   classification   diagnosis   MeSH
• Diagnosis, Differential MeSH
• DNA-Binding Proteins cerebrospinal fluid   MeSH
• Middle Aged MeSH
• Humans MeSH
• Neurofilament Proteins cerebrospinal fluid   MeSH
• Peptide Fragments cerebrospinal fluid   MeSH
• Autopsy MeSH
• Progranulins cerebrospinal fluid   MeSH
• 14-3-3 Proteins cerebrospinal fluid   MeSH
• tau Proteins cerebrospinal fluid   MeSH
• Cerebrospinal Fluid Proteins cerebrospinal fluid   MeSH
• Gene Expression Regulation MeSH
• Retrospective Studies MeSH
• Aged, 80 and over MeSH
• Aged MeSH
• Sensitivity and Specificity MeSH
• Check Tag
• Middle Aged MeSH
• Humans MeSH
• Male MeSH
• Aged, 80 and over MeSH
• Aged MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH