Prominent examples are amyloid beta and tau in Alzheimer's disease, α-synuclein in Parkinson's disease and transactive response DNA binding protein 43 kDa (TDP-43) in ALS and FTD.
<b>Results:</b> Plasma α-synuclein level was significantly increased in patients with PD and APS when compared with controls and FTD without parkinsonism (<i>p</i> < 0.01).
The SNCA duplication case presented with a clinical phenotype of frontotemporal dementia with marked behavioural changes, pyramidal signs, postural hypotension and transiently levodopa responsive parkinsonism.
To report a novel family carrying a heterozygous 6.4 Mb duplication of the SNCA locus with an atypical clinical presentation strongly reminiscent of frontotemporal dementia and late-onset pallidopyramidal syndromes and study phenotype-genotype correlations in SNCA locus duplications.
Ubiquitin-positive, tau- and alpha-synuclein-negative inclusions are hallmarks of frontotemporal lobar degeneration with ubiquitin-positive inclusions and amyotrophic lateral sclerosis.
Thus, although the tau pathologies of Guam PDC share similarities with AD, the composite Guam PDC neuropathology profile of tau, alpha-synuclein and 8, 12-iso-iPF(2alpha)-VI isoprostane reported here more closely resembles that seen in other tauopathies including frontotemporal dementias (FTDs), which may imply that Guam PDC and FTD tauopathies share underlying mechanisms of neurodegeneration.
Linkage to the alpha-synuclein gene and the Frontotemporal dementia with parkinsonism locus on chromosome 17 had previously been excluded in the families included in this study.
Mutations in the tau gene in familial forms of frontotemporal dementia and in the alpha-synuclein gene in familial cases of Parkinson's disease have provided causal links between the dysfunction of these proteins and neurodegeneration.
Importantly, the discovery of mutations in the tau gene in familial forms of frontotemporal dementia and of mutations in the alpha-synuclein gene in familial forms of Parkinson's disease has established that dysfunction of tau protein and alpha-synuclein can cause neurodegeneration.
Familial parkinsonism with dementia, linked to chromosome 17 (frontotemporal dementia with Parkinsonism (FTDP-17), and other tauopathies pathologically resembling PD plus AD, are often related to mutations of the tau gene, whereas familial PD with alpha-synuclein and Parkin mutations usually show no cognitive impairment.
Over the past year, mutations in the genes for tau and alpha-synuclein have been identified as the genetic causes of some familial forms of frontotemporal dementia and Parkinson's disease, respectively.