Review: An update on clinical, genetic and pathological aspects of frontotemporal lobar degenerations

<jats:p>The development of our understanding of frontotemporal dementia (<jats:styled-content style="fixed-case">FTD</jats:styled-content>) has gathered pace over the last 10 years. After taking a back seat to<jats:styled-content style="fixed-case">A</jats:styled-content>lzheimer's disease for many years<jats:styled-content style="fixed-case">FTD</jats:styled-content>has emerged as a significant group of heterogeneous diseases often affecting people under the age of 65.<jats:styled-content style="fixed-case">FTD</jats:styled-content>has also been brought into the spotlight as the major disease entities of the group have clinical, genetic and pathological links to motor neuron disease/amyotrophic lateral sclerosis, indicating that they form a disease spectrum. In this review, we overview how the pathological concept of frontotemporal lobar degeneration (<jats:styled-content style="fixed-case">FTLD</jats:styled-content>) and the clinical concept of<jats:styled-content style="fixed-case">FTD</jats:styled-content>evolved and show that<jats:styled-content style="fixed-case">FTLD</jats:styled-content>, once thought of as a single disorder, represents a heterogeneous group of diseases with overlapping clinical symptoms, multiple causative genes and varying underlying pathology. We also provide a brief summary of the clinical manifestations, summarize the major genetic aspects and describe the main pathological features seen in the different subtypes of<jats:styled-content style="fixed-case">FTLD</jats:styled-content>. We also summarize the correlations that exist between clinical presentations and pathological variants. An overview of the main pathogenic mechanisms is also provided.</jats:p>