SPTLC2 variants are associated with early-onset ALS and FTD due to aberrant sphingolipid synthesis.

OBJECTIVE: Amyotrophic lateral sclerosis (ALS) is a devastating, incurable neurodegenerative disease. A subset of ALS patients manifests with early-onset and complex clinical phenotypes. We aimed to elucidate the genetic basis of these cases to enhance our understanding of disease etiology and facilitate the development of targeted therapies. METHODS: Our research commenced with an in-depth genetic and biochemical investigation of two specific families, each with a member diagnosed with early-onset ALS (onset age of <40 years). This involved whole-exome sequencing, trio analysis, protein structure analysis, and sphingolipid measurements. Subsequently, we expanded our analysis to 62 probands with early-onset ALS and further included 440 patients with adult-onset ALS and 1163 healthy controls to assess the prevalence of identified genetic variants. RESULTS: We identified heterozygous variants in the serine palmitoyltransferase long chain base subunit 2 (SPTLC2) gene in patients with early-onset ALS. These variants, located in a region closely adjacent to ORMDL3, bear similarities to SPTLC1 variants previously implicated in early-onset ALS. Patients with ALS carrying these SPTLC2 variants displayed elevated plasma ceramide levels, indicative of increased serine palmitoyltransferase (SPT) activity leading to sphingolipid overproduction. INTERPRETATION: Our study revealed novel SPTLC2 variants in patients with early-onset ALS exhibiting frontotemporal dementia. The combination of genetic evidence and the observed elevation in plasma ceramide levels establishes a crucial link between dysregulated sphingolipid metabolism and ALS pathogenesis. These findings expand our understanding of ALS's genetic diversity and highlight the distinct roles of gene defects within SPT subunits in its development.

Tau filaments from amyotrophic lateral sclerosis/parkinsonism-dementia complex adopt the CTE fold.

The amyotrophic lateral sclerosis/parkinsonism-dementia complex (ALS/PDC) of the island of Guam and the Kii peninsula of Japan is a fatal neurodegenerative disease of unknown cause that is characterized by the presence of abundant filamentous tau inclusions in brains and spinal cords. Here, we used electron cryo-microscopy to determine the structures of tau filaments from the cerebral cortex of three cases of ALS/PDC from Guam and eight cases from Kii, as well as from the spinal cord of two of the Guam cases. Tau filaments had the chronic traumatic encephalopathy (CTE) fold, with variable amounts of Type I and Type II filaments. Paired helical tau filaments were also found in three Kii cases and tau filaments with the corticobasal degeneration fold in one Kii case. We identified a new Type III CTE tau filament, where protofilaments pack against each other in an antiparallel fashion. ALS/PDC is the third known tauopathy with CTE-type filaments and abundant tau inclusions in cortical layers II/III, the others being CTE and subacute sclerosing panencephalitis. Because these tauopathies are believed to have environmental causes, our findings support the hypothesis that ALS/PDC is caused by exogenous factors.

Protein profiling of extracellular vesicles from iPSC-derived astrocytes of patients with ALS/PDC in Kii peninsula.

BACKGROUND: Amyotrophic lateral sclerosis/Parkinsonism-dementia complex in Kii peninsula, Japan (Kii ALS/PDC), is an endemic neurodegenerative disease whose causes and pathogenesis remain unknown. However, astrocytes in autopsied cases of Kii ALS/PDC show characteristic lesions. In addition, relationships between extracellular vesicles (EVs) and neurodegenerative diseases are increasingly apparent. Therefore, we focused on proteins in EVs derived from Kii ALS/PDC astrocytes in the present study. METHODS: Induced pluripotent stem cells (iPSCs) derived from three healthy controls (HCs) and three patients with Kii ALS/PDC were differentiated into astrocytes. EVs in the culture medium of astrocytes were collected and subjected to quantitative proteome analysis. RESULTS: Our proteome analysis reveals that EV-containing proteins derived from astrocytes of patients with Kii ALS/PDC show distinctive patterns compared with those of HCs. Moreover, EVs derived from Kii ALS/PDC astrocytes display increased proteins related to proteostasis and decreased proteins related to anti-inflammation. DISCUSSION: Proteins contained in EVs from astrocytes unveil protective support to neurons and may reflect the molecular pathomechanism of Kii ALS/PDC; accordingly, they may be potential biomarker candidates of Kii ALS/PDC.

Tau Filaments from Amyotrophic Lateral Sclerosis/Parkinsonism-Dementia Complex (ALS/PDC) adopt the CTE Fold.

The amyotrophic lateral sclerosis/parkinsonism-dementia complex (ALS/PDC) of the island of Guam and the Kii peninsula of Japan is a fatal neurodegenerative disease of unknown cause that is characterised by the presence of abundant filamentous tau inclusions in brains and spinal cords. Here we used electron cryo-microscopy (cryo-EM) to determine the structures of tau filaments from the cerebral cortex of three cases of ALS/PDC from Guam and eight cases from Kii, as well as from the spinal cord of two of the Guam cases. Tau filaments had the chronic traumatic encephalopathy (CTE) fold, with variable amounts of Type I and Type II filaments. Paired helical tau filaments were also found in two Kii cases. We also identified a novel Type III CTE tau filament, where protofilaments pack against each other in an anti-parallel fashion. ALS/PDC is the third known tauopathy with CTE-type filaments and abundant tau inclusions in cortical layers II/III, the others being CTE and subacute sclerosing panencephalitis. Because these tauopathies are believed to have environmental causes, our findings support the hypothesis that ALS/PDC is caused by exogenous factors.

APOE Alleles With Tau and Aß Pathology in Patients With Amyotrophic Lateral Sclerosis and Parkinsonism-Dementia Complex in the Kii Peninsula.

BACKGROUND AND OBJECTIVES: To examine the association of the APOE ε4 and ε2 alleles with the pathologic features of patients with amyotrophic lateral sclerosis and parkinsonism-dementia complex cases in the Kii peninsula of Japan (Kii ALS/PDC). METHODS: We analyzed APOE variants in 18 autopsy patients with ALS/PDC, consisting of 9, 8, and 1 patient with PDC, ALS, and PDC followed by ALS, respectively. Moreover, we revealed the relationship between APOE variants and Aß and tau pathologies. RESULTS: The frequency of the ε4 allele was not different between patients with Kii ALS/PDC and control participants. APOE ε4 was associated with increased Aß pathology (p = 0.005 by the χ 2 test), but not with increased tau pathology (p = 0.984). The frequency of the ε2 allele was apparently higher than that of control participants (p = 0.254). The APOE ε2 allele was associated with increased tau pathology (p = 0.009) and not with reduced Aß pathology (p = 0.383) in patients with Kii ALS/PDC. DISCUSSION: Although there was no overrepresentation of the frequency of the ε4 or ε2 allele, our findings suggest that the ε2 allele is associated with increased tau pathology and not with reduced Aß pathology in patients with Kii ALS/PDC.

An immigrant family with Kii amyotrophic lateral sclerosis/parkinsonism-dementia complex.

OBJECTIVES: Amyotrophic lateral sclerosis/parkinsonism-dementia complex (ALS/PDC) is a unique endemic on Guam island of the USA, the Kii Peninsula of Japan, and Papua state of Indonesia. The pathomechanism of ALS/PDC remains to be solved, although interaction between some environmental factors and genetic background is plausible. This is the first autopsy-proven immigrant family of ALS/PDC of the Kii Peninsula. METHODS: A daughter and her father immigrated to the high incident area from outside the Kii Peninsula. The father developed ALS 18 years later after immigration, and his daughter also developed ALS 65 years after immigration. They showed pure ALS phenotype without parkinsonism and dementia. RESULTS: The daughter was diagnosed neuropathologically with Kii ALS/PDC with multiple proteinopathies: tauopathy, α-synucleinopathy, and TDP-43 proteinopathy. Gene analysis of familial ALS-related genes, including C9orf72, showed no mutation. DISCUSSION: The findings in an immigrant family established that certain environmental factors play a critical role in the pathogenesis of Kii ALS/PDC.

Expression of Mutant Ubiquitin and Proteostasis Impairment in Kii Amyotrophic Lateral Sclerosis/Parkinsonism-Dementia Complex Brains.

Kii amyotrophic lateral sclerosis/parkinsonism-dementia complex (ALS/PDC) is a progressive neurodegenerative disorder that is endemic to the Kii peninsula of Japan. The disorder is clinically characterized by a variable combination of parkinsonism, dementia, and motor neuron symptoms. Despite extensive investigations, the etiology and pathogenesis of ALS/PDC remain unclear. At the neuropathological level, Kii ALS/PDC is characterized by neuronal loss and tau-dominant polyproteinopathy. Here, we report the accumulation of several proteins involved in protein homeostasis pathways, that is, the ubiquitin-proteasome system and the autophagy-lysosome pathway, in postmortem brain tissue from a number of Kii ALS/PDC cases (n = 4). Of particular interest is the presence of a mutant ubiquitin protein (UBB+1), which is indicative of disrupted ubiquitin homeostasis. The findings suggest that abnormal protein aggregation is linked to impaired protein homeostasis pathways in Kii ALS/PDC.

Brain Transcriptome Analysis Links Deficiencies of Stress-Responsive Proteins to the Pathomechanism of Kii ALS/PDC.

Amyotrophic lateral sclerosis and Parkinsonism-dementia complex (ALS/PDC) is a unique endemic neurodegenerative disease, with high-incidence foci in Kii Peninsula, Japan. To gather new insights into the pathological mechanisms underlying Kii ALS/PDC, we performed transcriptome analyses of patient brains. We prepared frozen brains from three individuals without neurodegenerative diseases, three patients with Alzheimer's disease, and 21 patients with Kii ALS/PDC, and then acquired microarray data from cerebral gray and white matter tissues. Microarray results revealed that expression levels of genes associated with heat shock proteins, DNA binding/damage, and senescence were significantly altered in patients with ALS/PDC compared with healthy individuals. The RNA expression pattern observed for ALS-type brains was similar to that of PDC-type brains. Additionally, pathway and network analyses indicated that the molecular mechanism underlying ALS/PDC may be associated with oxidative phosphorylation of mitochondria, ribosomes, and the synaptic vesicle cycle; in particular, upstream regulators of these mechanisms may be found in synapses and during synaptic trafficking. Furthermore, phenotypic differences between ALS-type and PDC-type were observed, based on HLA haplotypes. In conclusion, determining the relationship between stress-responsive proteins, synaptic dysfunction, and the pathogenesis of ALS/PDC in the Kii peninsula may provide new understanding of this mysterious disease.

[The Current State of Amyotrophic Lateral Sclerosis/Parkinsonism-Dementia Complex in the Kii Peninsula, Japan, 2019].

Recent papers of amyotrophic lateral sclerosis/parkinsonism-dementia complex in the Kii peninsula, Japan (Kii ALS/PDC), published since 2015, were reviewed The studies included transition element of scalp hair analysis, dopaminergic PET study, review of life style changes in the high incident area, neurotoxic BMAA analysis, a clinical report of a migration case, comprehensive neuropathological study, cerebellar tau pathology, nitrative stress in the central nervous system study, optinurin pathology in the spinal cord, and tau PET study. Tau PET was advocated to be a new useful tool for diagnosis, even in the early stage of ALS/PDC with tauopathy. The etiology of Kii ALS/PDC remainds unknown. There are patients and healthy residents within the same environment in the high incidence foci, therefore it is difficult to explain this result by exposure to environmental factors alone. From the genetic viewpoint, rare-disease and rare-variant model may be applied to Kii ALS/PDC. Because there was an immigrant who was diagnosed neuropathologically, and a drastic decrease of the prevalence in the past several decades in the high incident area, it is feasible that Kii ALS/PDC is a multifactorial disease caused by both risk genes and environmental factors. Identifying risk genes and environmental factors for Kii ALS/PDC may contribute to the prevention of neurodegenerative diseases.

Tau imaging detects distinctive distribution of tau pathology in ALS/PDC on the Kii Peninsula.

OBJECTIVE: To characterize the distribution of tau pathology in patients with amyotrophic lateral sclerosis/parkinsonism dementia complex on the Kii Peninsula (Kii ALS/PDC) by tau PET using [11C]PBB3 as ligand. METHODS: This is a cross-sectional study of 5 patients with ALS/PDC and one asymptomatic participant with a dense family history of ALS/PDC from the Kii Peninsula who took part in this study. All were men, and their age was 76 ± 8 (mean ± SD) years. Thirteen healthy men (69 ± 6 years) participated as healthy controls (HCs). Dynamic PET scans were performed following injection of [11C]PBB3, and parametric PET images were generated by voxel-by-voxel calculation of binding potential (BP* ND) using a multilinear reference tissue model. [11C] Pittsburgh compound B (PiB) PET, MRI, and cognitive tests were also performed. RESULTS: A voxel-based comparison of [11C]PBB3 BP* ND illustrated PET-detectable tau deposition in the cerebral cortex and white matter, and pontine basis including the corticospinal tract in Kii ALS/PDC patients compared with HCs (uncorrected p < 0.05). Group-wise volume of interest analysis of [11C]PBB3 BP* ND images showed increased BP* ND in the hippocampus and in frontal and parietal white matters of Kii ALS/PDC patients relative to HCs (p < 0.05, Holm-Sidak multiple comparisons test). BP* ND in frontal, temporal, and parietal gray matters correlated with Mini-Mental State Examination scores in Kii ALS/PDC patients (p < 0.05). All Kii ALS/PDC patients were negative for [11C]PiB (ß-amyloid) except one with marginal positivity. CONCLUSION: [11C]PBB3 PET visualized the characteristic topography of tau pathology in Kii ALS/PDC, corresponding to clinical phenotypes of this disease.

Amyotrophic lateral sclerosis and parkinsonism-dementia complex of the Hohara focus of the Kii Peninsula: A multiple proteinopathy?

The high incidence of amyotrophic lateral sclerosis (ALS) and parkinsonism-dementia complex (PDC) has been previously known in the Kii Peninsula of Japan and in Guam. Recently, the accumulation of various proteins, such as tau, trans-activation response DNA binding protein 43 kDa (TDP-43), and alpha-synuclein (αSyn), was reported in the brains of patients with ALS/PDC in Guam. To confirm whether similar findings are present in Kii ALS/PDC, we neuropathologically examined the brains and spinal cords of 18 patients with ALS/PDC (clinical diagnoses: eight ALS and 10 PDC) in Hohara Village, which is the eastern focus of Kii ALS. The average age at death was 71.6 years, and 16 patients (88.9%) had a family history of ALS/PDC. Autopsy specimens were immunohistochemically examined with antibodies against four major proteins. Neurofibrillary tangles, including ghost tangles, and tau-positive astrocytes were distributed widely in all of the brains examined, and TDP-43-positive neuronal cytoplasmic inclusions were observed mainly in the limbic system. Synuclein pathology was present in 14 patients (77.8%). These patients were classified into three pathological subtypes according to the most prominent proteinopathy: the tauopathy-dominant type, the TDP-43 proteinopathy-dominant type, and the synucleinopathy-dominant type. Five patients with severe tau deposition showed clinical features of atypical parkinsonism and dementia with or without motor neuron disease. Eight patients were predominated by phosphorylated TDP-43 inclusions and clinically showed ALS, and five patients were predominated by synuclein pathology and clinically showed signs of PDC. Based on the common characteristic tau pathology, three subtypes seemed to be pathologically continuous on a spectrum of a single disease. Thus, we conclude that ALS/PDC in the Hohara focus of the Kii Peninsula is a single disease characterized neuropathologically by a multiple proteinopathy, even though the clinical manifestations of the three subtypes differed from each other. It remains unclear whether the coexistence of the three proteinopathies was incidental or pathogenetically related.

A migration case of Kii amyotrophic lateral sclerosis/parkinsonism dementia complex with the shortest stay in the endemic area and the longest incubation to develop the disease.

Amyotrophic lateral sclerosis/parkinsonism dementia complex (ALS/PDC) is an endemic disease observed in the Kii peninsula, Guam, and Papua. We report a case of a 76-year old man with ALS/PDC of the Kii peninsula of Japan (Kii ALS/PDC). The patient was born and grew up in the Kii peninsula. He moved out at age three, and developed symptoms 73years later. He showed pyramidal sign, parkinsonian symptoms, and mildly impaired cognitive function. 131I-metaiodobenzylguanidine myocardial scintigraphy showed decreased cardiac sympathetic nerve function, and dopamine transporter single photon emission computed tomography imaging showed decreased 123I-N-ω-fluoropropyl-2ß-carbomethoxy3ß-(4-iodophenyl) nortropane accumulation. Cerebral blood flow showed hypoperfusion. Positron emission tomography showed widespread tau deposition in his brain. This is a migration case of Kii ALS/PDC with the shortest stay in the endemic area and the longest delay to develop the disease, indicating a genetic factor for the disease development in a considerable degree.

Lifestyle Changes and Oxidative Stress in a High-incidence Area of Amyotrophic Lateral Sclerosis in the Southwestern Kii Peninsula, Japan.

Objective Lifestyle changes may play an important role in the incidence reduction and delay of onset age of amyotrophic lateral sclerosis (ALS) in the Koza/Kozagawa/Kushimoto (K) area. The aim of this study was to evaluate recent lifestyle changes in the K area and to investigate the relationships between lifestyle and oxidative stress among the residents. Methods We conducted a medical checkup for elderly residents in the K area and the control area and evaluated the urinary 8-OHdG levels, cognitive function test scores and metal contents in serum and scalp hair, coupled with a lifestyle questionnaire survey between 2010 and 2015. Results Recent lifestyle changes among the K residents, including a decrease in the Japanese pickle consumption, increase in fresh vegetable consumption and decrease in farm work, were evaluated in this study. Low consumption of Japanese pickles, high consumption of fresh vegetables, rare farm work and low levels of 8-OHdG/creatinine were all associated with high scores in the cognitive function tests. Frequent farm work and consumption of Japanese pickles was associated with high contents of transition metals, such as Mn, Al and V, in the scalp hair. Conclusion These lifestyle changes among residents in the K area may be associated with their oxidative stress.

Nitrative Stress and Tau Accumulation in Amyotrophic Lateral Sclerosis/Parkinsonism-Dementia Complex (ALS/PDC) in the Kii Peninsula, Japan.

Objective: The Kii Peninsula of Japan is known to be a high incidence area of amyotrophic lateral sclerosis/parkinsonism-dementia complex (Kii ALS/PDC) with tauopathy. Nitrative stress and oxidative stress on ALS/PDC and their relationship to tau pathology were clarified. Methods: Seven patients with Kii ALS/PDC (3 males and 4 females, average age 70.7 years, 3 with ALS, 2 with ALS with dementia, and 2 with PDC) were analyzed in this study. Five patients with Alzheimer's disease and five normal aged subjects were used as controls. Immunohistochemical analysis was performed on formalin-fixed, paraffin-embedded temporal lobe sections (the hippocampal area including hippocampus, prosubiculum, subiculum, presubiculum, and parahippocampal gyri) using antibodies to detect phosphorylated tau (anti-AT-8), nitrated guanine (anti-8-NG), anti-iNOS, anti-NFκB, and oxidized guanine (anti-8-OHdG) antibodies. Results: Most hippocampal neurons of Kii ALS/PDC patients were stained with anti-8-NG, anti-iNOS, anti-NFκB, and anti-8-OHdG antibodies and some AT-8 positive neurons were co-stained with anti-8-NG antibody. The numbers of 8-NG positive neurons and 8-OHdG positive neurons were greater than AT-8 positive neurons and the number of 8-NG positive neurons was larger in patients with Kii ALS/PDC than in controls. Conclusion: Nitrative and oxidative stress may take priority over tau accumulation and lead to the neurodegeneration in Kii ALS/PDC.

[An Autopsy Case of Globular Glial Tauopathy Presenting with Amyotrophic Lateral Sclerosis with Dementia].

We report an autopsy case of globular glial tauopathy (GGT) presenting clinically with amyotrophic lateral sclerosis (ALS) with dementia. A 79-year-old female developed weakness in the right upper limb, which progressed gradually. She developed apathy and speech disorder at 80 years of age. On neurological examination, she showed signs of upper and lower motor neuron disorder and dementia, but no extrapyramidal signs. The clinical diagnosis was ALS with dementia. The autopsy revealed left predominant marked atrophy of the frontal lobe due to severe neuronal loss and Gliosis. Immunohistochemistry using anti-4-repeat tau antibody revealed numerous globular glial inclusions. Severe neurodegeneration in the primary motor cortex and corticospinal tract was observed. There were distinctive tau-positive inclusions in both Betz and anterior horn cells. TDP-43-positive inclusions in motor neurons were not detected. Sequence analysis of the tau gene revealed no mutations in exons 1-5, 7, 9-13, or the adjacent intronic sequences. GGT can cause a clinical phenotype of ALS with dementia. (Received December 28, 2015; Accepted February 23, 2016; Published August 1, 2016).