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Frontotemporal lobar degeneration (FTLD) is a pathological process that occurs in frontotemporal dementia. It is characterized by atrophy in the frontal lobe and temporal lobe of the brain, with sparing of the parietal and occipital lobes. Common proteinopathies that are found in FTLD include the accumulation of Tau proteins and TARDBPs. Mutations in the C9orf72 gene have been established as a major genetic contribution of FTLD, although defects in the GRN and MAPT genes are also associated with it. == Classification == There are 3 main histological subtypes found at post-mortem: *FTLD-tau is characterised by tau positive inclusions often referred to as Pick-bodies. Examples of FTLD-tau include; Pick's disease, corticobasal degeneration, progressive supranuclear palsy. *FTLD-TDP (or FTLD-U ) is characterised by ubiquitin and TDP-43 positive, tau negative, FUS negative inclusions. The pathological histology of this subtype is so diverse it is subdivided into four subtypes based on the detailed histological findings: : *Type A presents with many small neurites and neuronal cytoplasmic inclusions in the upper (superficial) cortical layers. Bar-like neuronal intranuclear inclusions can also be seen they are fewer in number. This type is associated with C9ORF72 mutations (see next section). : *Type B presents with lots of neuronal and glial cytoplasmic inclusions in both the upper (superficial) and lower (deep) cortical layers, and lower motor neurons. However neuronal intranuclear inclusions are rare or absent. This is often associated with ALS : *Type C presents many long neuritic profiles found in the superficial cortical laminae, very few or no neuronal cytoplasmic inclusions, neuronal intranuclear inclusions or glial cytoplasmic inclusions. This is often associated with semantic dementia. : *Type D presents with lots of neuronal intranuclear inclusions and dystrophic neurites, and an unusual absence of inclusions in the granual cell layer of the hippocampus. Type 4 is associated with VCP mutations. Two physicians independently categorized the various forms of TDP-43 associated disorders. Both classifications were considered equally valid by the medical community, but the physicians in question have jointly proposed a compromise classification to avoid confusion. *FTLD-FUS; which is characterised by FUS positive cytoplasmic inclusions, intra nuclear inclusions, and neuritic threads. All of which are present in the cortex, medulla, hippocampus, and motor cells of the spinal cord and XIIth cranial nerve. Dementia lacking distinctive histology (DLDH) is a rare and controversial entity. New analyses has allowed many cases previously described as DLDH to be reclassified into one of the positively defined subgroups. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Frontotemporal lobar degeneration」の詳細全文を読む スポンサード リンク
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