The shared ancestry between the C9orf72 hexanucleotide repeat expansion and intermediate-length alleles using haplotype sharing trees and HAPTK.

The C9orf72 hexanucleotide repeat expansion (HRE) is a common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). The inheritance is autosomal dominant, but a high proportion of subjects with the mutation are simplex cases. One possible explanation is de novo expansions of unstable intermediate-length alleles (IAs). Using haplotype sharing trees (HSTs) with the haplotype analysis tool kit (HAPTK), we derived majority-based ancestral haplotypes of HRE samples and discovered that IAs containing ≥18-20 repeats share large haplotypes in common with the HRE. Using HSTs of HRE and IA samples, we demonstrate that the longer IA haplotypes are largely indistinguishable from HRE haplotypes and that several ≥18-20 IA haplotypes share over 5 Mb (>600 markers) haplotypes in common with the HRE haplotypes. These analysis tools allow physical understanding of the haplotype blocks shared with the majority-based ancestral haplotype. Our results demonstrate that the haplotypes with longer IAs belong to the same pool of haplotypes as the HRE and suggest that longer IAs represent potential premutation alleles.

Limbic-predominant age-related TDP-43 encephalopathy in the oldest old: a population-based study.

Population-based cohort studies are essential for understanding the pathological basis of dementia in older populations. Previous studies have shown that limbic-predominant age-related TDP-43 encephalopathy neuropathological change (LATE-NC) increases with age, but there have been only a few studies, which have investigated this entity in a population-based setting. Here we studied the frequency of LATE-NC and its associations with other brain pathologies and cognition in a population aged ≥ 85 years. The population-based Vantaa 85+ study cohort includes all 601 individuals aged ≥ 85 years who were living in Vantaa, Finland in 1991. A neuropathological examination was performed on 304 subjects (50.5%) and LATE-NC staging was possible in 295 of those. Dementia status and Mini-Mental State Examination (MMSE) scores were defined in the baseline study and 3 follow-ups (1994-99). The LATE-NC stages were determined based on TDP-43 immunohistochemistry, according to recently updated recommendations. Arteriolosclerosis was digitally assessed by calculating the average sclerotic index of five random small arterioles in amygdala and hippocampal regions, and frontal white matter. The association of LATE-NC with arteriolosclerosis and previously determined neuropathological variables including Alzheimer's disease neuropathological change (ADNC), Lewy-related pathology (LRP), hippocampal sclerosis (HS), and cerebral amyloid angiopathy (CAA), and cognitive variables were analysed by Fisher's exact test, linear and logistic regression (univariate and multivariate) models. LATE-NC was found in 189 of 295 subjects (64.1%). Stage 2 was the most common (28.5%) and stage 3 the second most common (12.9%), whereas stages 1a, 1b and 1c were less common (9.5%, 5.1% and 8.1%, respectively). Stages 1a (P < 0.01), 2 (P < 0.001) and 3 (P < 0.001) were significantly associated with dementia and lower MMSE scores. LATE-NC was associated with ADNC (P < 0.001), HS (P < 0.001), diffuse neocortical LRP (P < 0.002), and arteriolosclerosis in amygdala (P < 0.02). In most cases LATE-NC occurred in combination alongside other neuropathological changes. There were only six subjects with dementia who had LATE-NC without high levels of ADNC or LRP (2% of the cohort, 3% of the cases with dementia), and five of these had HS. In all multivariate models, LATE-NC was among the strongest independent predictors of dementia. When LATE-NC and ADNC were assessed in a multivariate model without other dementia-associated pathologies, the attributable risk was higher for LATE-NC than ADNC (24.2% vs. 18.6%). This population-based study provides evidence that LATE-NC is very common and one of the most significant determinants of dementia in the general late-life aged population.

Genetic evaluation of dementia with Lewy bodies implicates distinct disease subgroups.

The APOE locus is strongly associated with risk for developing Alzheimer's disease and dementia with Lewy bodies. In particular, the role of the APOE ε4 allele as a putative driver of α-synuclein pathology is a topic of intense debate. Here, we performed a comprehensive evaluation in 2466 dementia with Lewy bodies cases versus 2928 neurologically healthy, aged controls. Using an APOE-stratified genome-wide association study approach, we found that GBA is associated with risk for dementia with Lewy bodies in patients without APOE ε4 (P = 6.58 × 10-9, OR = 3.41, 95% CI = 2.25-5.17), but not with dementia with Lewy bodies with APOE ε4 (P = 0.034, OR = 1.87, 95%, 95% CI = 1.05-3.37). We then divided 495 neuropathologically examined dementia with Lewy bodies cases into three groups based on the extent of concomitant Alzheimer's disease co-pathology: pure dementia with Lewy bodies (n = 88), dementia with Lewy bodies with intermediate Alzheimer's disease co-pathology (n = 66) and dementia with Lewy bodies with high Alzheimer's disease co-pathology (n = 341). In each group, we tested the association of the APOE ε4 against the 2928 neurologically healthy controls. Our examination found that APOE ε4 was associated with dementia with Lewy bodies + Alzheimer's disease (P = 1.29 × 10-32, OR = 4.25, 95% CI = 3.35-5.39) and dementia with Lewy bodies + intermediate Alzheimer's disease (P = 0.0011, OR = 2.31, 95% CI = 1.40-3.83), but not with pure dementia with Lewy bodies (P = 0.31, OR = 0.75, 95% CI = 0.43-1.30). In conclusion, although deep clinical data were not available for these samples, our findings do not support the notion that APOE ε4 is an independent driver of α-synuclein pathology in pure dementia with Lewy bodies, but rather implicate GBA as the main risk gene for the pure dementia with Lewy bodies subgroup.

Primary age-related tauopathy in a Finnish population-based study of the oldest old (Vantaa 85+).

AIMS: Few studies have investigated primary age-related tauopathy (PART) in a population-based setting. Here, we assessed its prevalence, genetic background, comorbidities and features of cognitive decline in an unselected elderly population. METHODS: The population-based Vantaa 85+ study includes all 601 inhabitants of Vantaa aged ≥ 85 years in 1991. Neuropathological assessment was possible in 301. Dementia (DSM IIIR criteria) and Mini-Mental State Examination (MMSE) scores were assessed at the baseline of the study and follow-ups. PART subjects were identified according to the criteria by Crary et al and were compared with subjects with mild and severe Alzheimer's disease (AD) neuropathological changes. The effects of other neuropathologies were taken into account using multivariate and sensitivity assays. Genetic analyses included APOE genotypes and 29 polymorphisms of the MAPT 3' untranslated region (3'UTR region). RESULTS: The frequency of PART was 20% (n = 61/301, definite PART 5%). When PART subjects were compared with those with severe AD pathology, dementia was less common, its age at onset was higher and duration shorter. No such differences were seen when compared with those with milder AD pathology. However, both AD groups showed a steeper decline in MMSE scores in follow-ups compared with PART. APOE ε4 frequency was lower, and APOE ε2 frequency higher in the PART group compared with each AD group. The detected nominally significant associations between PART and two MAPT 3'UTR polymorphisms and haplotypes did not survive Bonferroni correction. CONCLUSIONS: PART is common among very elderly. PART subjects differ from individuals with AD-type changes in the pattern of cognitive decline, associated genetic and neuropathological features.

Lewy-related pathology exhibits two anatomically and genetically distinct progression patterns: a population-based study of Finns aged 85.

According to a generally accepted concept Lewy-related pathology (LRP) follows hierarchical caudo-rostral progression. LRP is also frequently present concomitantly with Alzheimer's disease (AD), and it has been hypothesized that AD-associated LRP forms a distinct type of α-synucleinopathy, where LRP originates in the amygdala. The frequency of distinct forms of LRP progression types has not been studied in a population-based setting. We investigated the distribution and progression of LRP and its relation to AD pathology and apolipoprotein (APOE) ε4 in a population-based sample of Finns aged over 85 years (N = 304). Samples from spinal cord to neocortical areas representing 11 anatomical sites without any hierarchical selection were analyzed immunohistochemically (α-synuclein antibody clone 5G4). LRP was present in 124 individuals (41%) and according to DLB Consortium guidelines 19 of them were categorized as brainstem, 10 amygdala-predominant, 41 limbic, and 43 diffuse neocortical type, whereas 11 could not be classified. To determine the LRP progression patterns, a systematic anatomical scoring was carried out by taking into account the densities of the semiquantitative LRP scores in each anatomic site. With this scoring 123 (99%) subjects could be classified into two progression pattern types: 67% showed caudo-rostral and 32% amygdala-based progression. The unsupervised statistical K-means cluster analysis was used as a supplementary test and supported the presence of two progression patterns and had a 90% overall concordance with the systematic anatomical scoring method. Severe Braak NFT stage, high CERAD score and APOE ε4 were significantly (all p < 0.00001) associated with amygdala-based, but not with caudo-rostral progression type (all p > 0.2). This population-based study demonstrates two distinct common LRP progression patterns in the very elderly population. The amygdala-based pattern was associated with APOE ε4 and AD pathology. The results confirm the previous progression hypotheses but also widen the concept of the AD-associated LRP.

Job-related exhaustion risk variant in UST is associated with dementia and DNA methylation.

Previous genome-wide association and replication study for job-related exhaustion indicated a risk variant, rs13219957 in the UST gene. Epidemiological studies suggest connection of stress-related conditions and dementia risk. Therefore, we first studied association of rs13219957 and register-based incident dementia using survival models in the Finnish National FINRISK study surveys (N = 26,693). The AA genotype of rs13219957 was significantly associated with 40% increased risk of all-cause dementia. Then we analysed the UST locus association with brain pathology in the Vantaa 85+ cohort and found association with tau pathology (Braak stage) but not with amyloid pathology. Finally, in the functional analyses, rs13219957 showed a highly significant association with two DNA methylation sites of UST, and UST expression. Thus, the results suggest a common risk variant for a stress-related condition and dementia. Mechanisms to mediate the connection may include differential DNA methylation and transcriptional regulation of UST.

Differential methylation analysis in neuropathologically confirmed dementia with Lewy bodies.

Dementia with Lewy bodies (DLB) is a common form of dementia in the elderly population. We performed genome-wide DNA methylation mapping of cerebellar tissue from pathologically confirmed DLB cases and controls to study the epigenetic profile of this understudied disease. After quality control filtering, 728,197 CpG-sites in 278 cases and 172 controls were available for the analysis. We undertook an epigenome-wide association study, which found a differential methylation signature in DLB cases. Our analysis identified seven differentially methylated probes and three regions associated with DLB. The most significant CpGs were located in ARSB (cg16086807), LINC00173 (cg18800161), and MGRN1 (cg16250093). Functional enrichment evaluations found widespread epigenetic dysregulation in genes associated with neuron-to-neuron synapse, postsynaptic specialization, postsynaptic density, and CTCF-mediated synaptic plasticity. In conclusion, our study highlights the potential importance of epigenetic alterations in the pathogenesis of DLB and provides insights into the modified genes, regions and pathways that may guide therapeutic developments.

Genome sequence analyses identify novel risk loci for multiple system atrophy.

Multiple system atrophy (MSA) is an adult-onset, sporadic synucleinopathy characterized by parkinsonism, cerebellar ataxia, and dysautonomia. The genetic architecture of MSA is poorly understood, and treatments are limited to supportive measures. Here, we performed a comprehensive analysis of whole genome sequence data from 888 European-ancestry MSA cases and 7,128 controls to systematically investigate the genetic underpinnings of this understudied neurodegenerative disease. We identified four significantly associated risk loci using a genome-wide association study approach. Transcriptome-wide association analyses prioritized USP38-DT, KCTD7, and lnc-KCTD7-2 as novel susceptibility genes for MSA within these loci, and single-nucleus RNA sequence analysis found that the associated variants acted as cis-expression quantitative trait loci for multiple genes across neuronal and glial cell types. In conclusion, this study highlights the role of genetic determinants in the pathogenesis of MSA, and the publicly available data from this study represent a valuable resource for investigating synucleinopathies.

C9orf72 hexanucleotide repeat allele tagging SNPs: Associations with ALS risk and longevity.

C9orf72 hexanucleotide repeat expansion is a common cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). The C9orf72 locus may harbor residual risk outside the hexanucleotide repeat expansion, but the evidence is conflicting. Here, we first compared 683 unrelated amyotrophic lateral sclerosis cases and 3,196 controls with Finnish ancestry to find best single nucleotide polymorphisms that tag the C9orf72 hexanucleotide repeat expansion and intermediate-length alleles. Rs2814707 was the best tagging single nucleotide polymorphisms for intermediate-length alleles with ≥7 repeats (p = 5 × 10-307) and rs139185008 for the hexanucleotide repeat expansion (p = 7 × 10-114) as well as alleles with ≥20 repeats. rs139185008*C associated with amyotrophic lateral sclerosis after removing cases with the hexanucleotide repeat expansion, especially in the subpopulation homozygous for the rs2814707*T (p = 0.0002, OR = 5.06), which supports the concept of residual amyotrophic lateral sclerosis risk at the C9orf72 haplotypes other than the hexanucleotide repeat expansion. We then leveraged Finnish biobank data to test the effects of rs2814707*T and rs139185008*C on longevity after removing individuals with amyotrophic lateral sclerosis / frontotemporal dementia diagnoses. In the discovery cohort (n = 230,006), the frequency of rs139185008*C heterozygotes decreased significantly with age in the comparisons between 50 and 80 years vs. >80 years (p = 0.0005) and <50 years vs. >80 years (p = 0.0001). The findings were similar but less significant in a smaller replication cohort (2-sided p = 0.037 in 50-80 years vs. >80 years and 0.061 in <50 years vs. >80 years). Analysis of the allele frequencies in 5-year bins demonstrated that the decrease of rs139185008*C started after the age of 70 years. The hexanucleotide repeat expansion tagging single nucleotide polymorphisms decreasing frequency with age suggests its' association with age-related diseases probably also outside amyotrophic lateral sclerosis / frontotemporal dementia.

Genome-wide structural variant analysis identifies risk loci for non-Alzheimer's dementias.

We characterized the role of structural variants, a largely unexplored type of genetic variation, in two non-Alzheimer's dementias, namely Lewy body dementia (LBD) and frontotemporal dementia (FTD)/amyotrophic lateral sclerosis (ALS). To do this, we applied an advanced structural variant calling pipeline (GATK-SV) to short-read whole-genome sequence data from 5,213 European-ancestry cases and 4,132 controls. We discovered, replicated, and validated a deletion in TPCN1 as a novel risk locus for LBD and detected the known structural variants at the C9orf72 and MAPT loci as associated with FTD/ALS. We also identified rare pathogenic structural variants in both LBD and FTD/ALS. Finally, we assembled a catalog of structural variants that can be mined for new insights into the pathogenesis of these understudied forms of dementia.

ALS in Finland: Major Genetic Variants and Clinical Characteristics of Patients With and Without the C9orf72 Hexanucleotide Repeat Expansion.

Background and Objectives: To analyze the frequencies of major genetic variants and the clinical features in Finnish patients with amyotrophic lateral sclerosis (ALS) with or without the C9orf72 hexanucleotide repeat expansion. Methods: A cohort of patients with motor neuron disease was recruited between 1993 and 2020 at the Helsinki University Hospital and 2 second-degree outpatient clinics in Helsinki. Finnish ancestry patients with ALS fulfilled the diagnosis according to the revised El Escorial criteria and the Awaji-criteria. Two categories of familial ALS (FALS) were used. A patient was defined FALS-A if at least 1 first- or second-degree family member had ALS, and FALS-NP, if family members had additional neurologic or psychiatric endophenotypes. Results: Of the 815 patients, 25% had FALS-A and 45% FALS-NP. C9orf72 expansion (C9pos) was found in 256 (31%) of all patients, in 58% of FALS-A category, in 48% of FALS-NP category, and in 23 or 17% of sporadic cases using the FALS-A or FALS-NP definition. C9pos or SOD1 p.D91A homozygosity was found in 328 (40%) of the 815 patients. We compared demographic and clinical characteristics between C9pos and patients with unknown cause of ALS (Unk). We found that the age at onset was significantly earlier and survival markedly shorter in the C9pos vs Unk patients with ALS. The shortest survival was found in bulbar-onset male C9pos patients, whereas the longest survival was found in Unk limb-onset males. Older age at onset associated consistently with shorter survival in C9pos and Unk patients in both limb-onset and bulbar-onset groups. There were no significant differences in the frequencies of bulbar-onset and limb-onset patients in C9pos and Unk groups. ALS-frontotemporal dementia (FTD) was more common in C9pos (17%) than in Unk (4%) patients, and of all patients with ALS-FTD, 70% were C9pos. Discussion: These results provide further evidence for the short survival of C9orf72-associated ALS. A prominent role of the C9orf72 and SOD1 variants was found in the Finnish population. An unusually high frequency of C9pos was also found among patients with sporadic ALS. The enrichment of these 2 variants likely contributes to the high incidence of ALS in Finland.

A Novel Genetic Marker for the C9orf72 Repeat Expansion in the Finnish Population.

BACKGROUND: C9orf72 repeat expansion (C9exp) is the most common genetic cause underlying frontotemporal lobar degeneration (FTLD) and amyotrophic lateral sclerosis (ALS). However, detection of the C9exp requires elaborative methods. OBJECTIVE: Identification of C9exp carriers from genotyped cohorts could be facilitated by using single nucleotide polymorphisms (SNPs) as markers for the C9exp. METHODS: We elucidated the potential of the previously described Finnish risk haplotype, defined by the SNP rs3849942, to identify potential C9exp carriers among 218,792 Finns using the FinnGen database. The haplotype approach was first tested in an idiopathic normal pressure hydrocephalus (iNPH) patient cohort (European Alzheimer's Disease DNA BioBank) containing C9exp carriers by comparing intermediate (15-30) and full-length (> 60 repeats) C9exp carriers (n = 41) to C9exp negative patients (< 15 repeats, n = 801). RESULTS: In this analysis, rs3849942 was associated with carriership of C9exp (OR 8.44, p < 2×10-15), while the strongest association was found with rs139185008 (OR 39.4, p < 5×10-18). Unbiased analysis of rs139185008 in FinnGen showed the strongest association with FTLD (OR 4.38, 3×10-15) and motor neuron disease ALS (OR 5.19, 3×10-21). rs139185008 was the top SNP in all diseases (iNPH, FTLD, ALS), and further showed a strong association with ALS in the UK Biobank (p = 9.0×10-8). CONCLUSION: Our findings suggest that rs139185008 is a useful marker to identify potential C9exp carriers in the genotyped cohorts and biobanks originating from Finland.

APOE ε4 associates with increased risk of severe COVID-19, cerebral microhaemorrhages and post-COVID mental fatigue: a Finnish biobank, autopsy and clinical study.

Apolipoprotein E ε4 allele (APOE4) has been shown to associate with increased susceptibility to SARS-CoV-2 infection and COVID-19 mortality in some previous genetic studies, but information on the role of APOE4 on the underlying pathology and parallel clinical manifestations is scarce. Here we studied the genetic association between APOE and COVID-19 in Finnish biobank, autopsy and prospective clinical cohort datasets. In line with previous work, our data on 2611 cases showed that APOE4 carriership associates with severe COVID-19 in intensive care patients compared with non-infected population controls after matching for age, sex and cardiovascular disease status. Histopathological examination of brain autopsy material of 21 COVID-19 cases provided evidence that perivascular microhaemorrhages are more prevalent in APOE4 carriers. Finally, our analysis of post-COVID fatigue in a prospective clinical cohort of 156 subjects revealed that APOE4 carriership independently associates with higher mental fatigue compared to non-carriers at six months after initial illness. In conclusion, the present data on Finns suggests that APOE4 is a risk factor for severe COVID-19 and post-COVID mental fatigue and provides the first indication that some of this effect could be mediated via increased cerebrovascular damage. Further studies in larger cohorts and animal models are warranted.

Carriership of two copies of C9orf72 hexanucleotide repeat intermediate-length alleles is a risk factor for ALS in the Finnish population.

The hexanucleotide repeat expansion in intron 1 of the C9orf72 gene causes amyotrophic lateral sclerosis (ALS) and frontotemporal dementia. In addition to the effects of the pathogenic expansion, a role of intermediate-length alleles has been suggested in ALS, corticobasal degeneration and Parkinson's disease. Due to the rarity of intermediate-length alleles with over 20 repeats and the geographical variability in their frequency, large studies that account for population stratification are needed to elucidate their effects. To this aim, we used repeat-primed PCR and confirmatory PCR assays to determine the C9orf72 repeat allele lengths in 705 ALS patients and 3958 controls from Finland. After exclusion of expansion carriers (25.5% of the ALS patients and 0.2% of the controls), we compared the frequency of intermediate-length allele carriers of 525 ALS cases and 3950 controls using several intermediate-length allele thresholds (7-45, 17-45, 21-45, 24-45 and 24-30). The carriership of an intermediate-length allele did not associate with ALS (Fisher's test, all p ≥ 0.15) nor was there any association with survival (p ≥ 0.33), when we divided our control group into three age groups (18-65, 66-84 and 85-105 years). Carriership of two intermediate-length alleles was associated with ALS, when the longer allele was ≥ 17 repeats (p = 0.002, OR 5.32 95% CI 2.02-14.05) or ≥ 21 repeats (p = 0.00016, OR 15.21 95% CI 3.79-61.0). Our results show that intermediate-length alleles are a risk factor of ALS when present in both alleles, whereas carrying just one intermediate-length allele was not associated with ALS or survival.

Putative risk alleles for LATE-NC with hippocampal sclerosis in population-representative autopsy cohorts.

Limbic-predominant age-related TAR-DNA-binding protein-43 (TDP-43) encephalopathy with hippocampal sclerosis pathology (LATE-NC + HS) is a neurodegenerative disorder characterized by severe hippocampal CA1 neuron loss and TDP-43-pathology, leading to cognitive dysfunction and dementia. Polymorphisms in GRN, TMEM106B and ABCC9 are proposed as LATE-NC + HS risk factors in brain bank collections. To replicate these results in independent population-representative cohorts, hippocampal sections from brains donated to three such studies (Cambridge City over 75-Cohort [CC75C], Cognitive Function and Ageing Study [CFAS], and Vantaa 85+ Study) were stained with hematoxylin-eosin (n = 744) and anti-pTDP-43 (n = 713), and evaluated for LATE-NC + HS and TDP-43 pathology. Single nucleotide polymorphism genotypes in GRN rs5848, TMEM106B rs1990622 and ABCC9 rs704178 were determined. LATE-NC + HS (n = 58) was significantly associated with the GRN rs5848 genotype (χ2 (2) = 20.61, P < 0.001) and T-allele (χ2 (1) = 21.04, P < 0.001), and TMEM106B rs1990622 genotype (Fisher's exact test, P < 0.001) and A-allele (χ2 (1) = 25.75, P < 0.001). No differences in ABCC9 rs704178 genotype or allele frequency were found between LATE-NC + HS and non-LATE-NC + HS neuropathology cases. Dentate gyrus TDP-43 pathology associated with GRN and TMEM106B variations, but the association with TMEM106B nullified when LATE-NC + HS cases were excluded. Our results indicate that GRN and TMEM106B are associated with severe loss of CA1 neurons in the aging brain, while ABCC9 was not confirmed as a genetic risk factor for LATE-NC + HS. The association between TMEM106B and LATE-NC + HS may be independent of dentate TDP-43 pathology.

C9orf72 hexanucleotide repeat length in older population: normal variation and effects on cognition.

The hexanucleotide repeat expansion in C9orf72 is a common cause of amyotrophic lateral sclerosis/frontotemporal dementia and also rarely found in other psychiatric and neurodegenerative conditions. Alleles with >30 repeats are often considered an expansion, but the pathogenic repeat length threshold is still unclear. It is also unclear whether intermediate repeat length alleles (often defined either as 7-30 or 20-30 repeats) have clinically significant effects. We determined the C9orf72 repeat length distribution in 3142 older Finns (aged 60-104 years). The longest nonexpanded allele was 45 repeats. We found 7-45 repeats in 1036/3142 (33%) individuals, 20-45 repeats in 56/3142 (1.8%), 30-45 repeats in 12/3142 (0.38%), and expansion (>45 repeats) in 6/3142 (0.19%). There was no apparent clustering of neurodegenerative or psychiatric diseases in individuals with 30-45 repeats indicating that 30-45 repeats are not pathogenic. None of the 6 expansion carriers had a diagnosis of amyotrophic lateral sclerosis/frontotemporal dementia but 4 had a diagnosis of a neurodegenerative or psychiatric disease. Intermediate length alleles (categorized as 7-45 and 20-45 repeats) did not associate with Alzheimer's disease or cognitive impairment.

Oligogenic basis of sporadic ALS: The example of SOD1 p.Ala90Val mutation.

OBJECTIVE: To characterize the clinical and neuropathologic features of patients with amyotrophic lateral sclerosis (ALS) with the superoxide dismutase 1 (SOD1) p.Ala90Val mutation, as well as the mutation frequency and the role of oligogenic mechanisms in disease penetrance. METHODS: An index patient with autopsy-proven ALS was discovered to have the SOD1 p.Ala90Val mutation, which was screened in 2 Finnish ALS cohorts (n = 453). Additional contributing variants were analyzed from whole-genome or whole-exome sequencing data. RESULTS: Seven screened patients (1.5%) were found to carry the SOD1 heterozygous mutation. Allele-sharing analysis suggested a common founder haplotype. Common clinical features included limb-onset, long disease course, and sensory symptoms. No TDP43 pathology was observed. All cases were apparently sporadic, and pedigree analysis demonstrated that the mutation has reduced penetrance. Analysis of other contributing genes revealed a unique set of additional variants in each patient. These included previously described rare ANG and SPG11 mutations. One patient was compound heterozygous for SOD1 p.Ala90Val and p.Asp91Ala. CONCLUSIONS: Our data suggest that the penetrance of SOD1 p.Ala90Val is modulated by other genes and indicates highly individual oligogenic basis of apparently sporadic ALS. Additional genetic variants likely contributing to disease penetrance were very heterogeneous, even among Finnish patients carrying the SOD1 founder mutation.

Alzheimer risk loci and associated neuropathology in a population-based study (Vantaa 85+).

OBJECTIVE: To test the association of distinct neuropathologic features of Alzheimer disease (AD) with risk loci identified in genome-wide association studies. METHODS: Vantaa 85+ is a population-based study that includes 601 participants aged ≥85 years, of which 256 were neuropathologically examined. We analyzed 29 AD risk loci in addition to APOE ε4, which was studied separately and used as a covariate. Genotyping was performed using a single nucleotide polymorphism (SNP) array (341 variants) and imputation (6,038 variants). Participants with Consortium to Establish a Registry for Alzheimer Disease (CERAD) (neuritic Aß plaques) scores 0 (n = 65) vs score M + F (n = 171) and Braak (neurofibrillary tangle pathology) stages 0-II (n = 74) vs stages IV-VI (n = 119), and with capillary Aß (CapAß, n = 77) vs without (n = 179) were compared. Cerebral amyloid angiopathy (CAA) percentage was analyzed as a continuous variable. RESULTS: Altogether, 24 of the 29 loci were associated (at p < 0.05) with one or more AD-related neuropathologic features in either SNP array or imputation data. Fifteen loci associated with CERAD score, smallest p = 0.0002122, odds ratio (OR) 2.67 (1.58-4.49) at MEF2C locus. Fifteen loci associated with Braak stage, smallest p = 0.004372, OR 0.31 (0.14-0.69) at GAB2 locus. Twenty loci associated with CAA, smallest p = 7.17E-07, ß 14.4 (8.88-20) at CR1 locus. Fifteen loci associated with CapAß smallest p = 0.002594, OR 0.54 (0.37-0.81) at HLA-DRB1 locus. Certain loci associated with specific neuropathologic features. CASS4, CLU, and ZCWPW1 associated only with CAA, while TREM2 and HLA-DRB5 associated only with CapAß. CONCLUSIONS: AD risk loci differ in their association with neuropathologic features, and we show for the first time distinct risk loci for CAA and CapAß.

Heterozygous TYROBP deletion (PLOSLFIN) is not a strong risk factor for cognitive impairment.

Biallelic loss-of-function mutations in TYROBP and TREM2 cause a rare disease that resembles early-onset frontotemporal dementia with bone lesions called polycystic lipomembranous osteodysplasia with sclerosing leukoencephalopathy (PLOSL). Some PLOSL-causing variants in TREM2 have also been associated with Alzheimer's disease when heterozygous. Here, we studied the PLOSLFINTYROBP deletion that covers 4 of the gene's 5 exons. We genotyped 3220 older Finns (mean age 79, range 58-104) and found 11 deletion carriers (mean age 78, range 60-94). The carrier prevalence was 0.0034 (1 in 293) that matches previous findings in younger cohorts suggesting no significant early mortality. By comparing Mini-Mental State Examination (MMSE) scores and diagnoses of dementia, we did not find any significant differences between TYROBP deletion carriers and noncarriers (all p-values >0.5). Neuropathological analysis of 2 deletion carriers (aged 89 and 94 years) demonstrated only minimal beta amyloid pathology (Consortium to Establish a Registry for Alzheimer's Disease (CERAD) score 0). Collectively these results suggest that heterozygous carriership of the TYROBP deletion is not a major risk factor of cognitive impairment.