BACKGROUND: Pathogenic heterozygous mutations in the progranulin gene (GRN) are a key cause of frontotemporal dementia (FTD), leading to significantly reduced biofluid concentrations of the progranulin protein (PGRN). This has led to a number of ongoing therapeutic trials aiming to treat this form of FTD by increasing PGRN levels in mutation carriers. However, we currently lack a complete understanding of factors that affect PGRN levels and potential variation in measurement methods. Here, we aimed to address this gap in knowledge by systematically reviewing published literature on biofluid PGRN concentrations. METHODS: Published data including biofluid PGRN concentration, age, sex, diagnosis and GRN mutation were collected for 7071 individuals from 75 publications. The majority of analyses (72%) had focused on plasma PGRN concentrations, with many of these (56%) measured with a single assay type (Adipogen) and so the influence of mutation type, age at onset, sex, and diagnosis were investigated in this subset of the data. RESULTS: We established a plasma PGRN concentration cut-off between pathogenic mutation carriers and non-carriers of 74.8 ng/mL using the Adipogen assay based on 3301 individuals, with a CSF concentration cut-off of 3.43 ng/mL. Plasma PGRN concentration varied by GRN mutation type as well as by clinical diagnosis in those without a GRN mutation. Plasma PGRN concentration was significantly higher in women than men in GRN mutation carriers (p = 0.007) with a trend in non-carriers (p = 0.062), and there was a significant but weak positive correlation with age in both GRN mutation carriers and non-carriers. No significant association was seen with weight or with TMEM106B rs1990622 genotype. However, higher plasma PGRN levels were seen in those with the GRN rs5848 CC genotype in both GRN mutation carriers and non-carriers. CONCLUSIONS: These results further support the usefulness of PGRN concentration for the identification of the large majority of pathogenic mutations in the GRN gene. Furthermore, these results highlight the importance of considering additional factors, such as mutation type, sex and age when interpreting PGRN concentrations. This will be particularly important as we enter the era of trials for progranulin-associated FTD.

• Klíčová slova
• Frontotemporal dementia, Progranulin,
• MeSH
• frontotemporální demence * genetika   patologie   MeSH
• lidé MeSH
• membránové proteiny genetika   MeSH
• mezibuněčné signální peptidy a proteiny genetika   MeSH
• mutace genetika   MeSH
• progranuliny genetika   MeSH
• proteiny nervové tkáně genetika   MeSH
• virulence MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH
• systematický přehled MeSH
• Názvy látek
• GRN protein, human MeSH Prohlížeč
• membránové proteiny MeSH
• mezibuněčné signální peptidy a proteiny MeSH
• progranuliny MeSH
• proteiny nervové tkáně MeSH
• TMEM106B protein, human MeSH Prohlížeč

We evaluated the genetic contribution of the T cell-restricted intracellular antigen-1 gene (TIA1) in a European cohort of frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS) patients. Exonic resequencing of TIA1 in 1120 patients (693 FTD, 341 ALS, 86 FTD-ALS) and 1039 controls identified in total 5 rare heterozygous missense variants, affecting the TIA1 low-complexity domain (LCD). Only 1 missense variant, p.Met290Thr, identified in a familial FTD patient with disease onset at 64 years, was absent from controls yet received a combined annotation-dependent depletion score of 11.42. By contrast, 3 of the 4 variants also detected in unaffected controls, p.Val294Glu, p.Gln318Arg, and p.Ala381Thr, had combined annotation-dependent depletion scores greater than 20. Our findings in a large European patient-control series indicate that variants in TIA1 are not a common cause of ALS and FTD. The observation of recurring TIA1 missense variants in unaffected individuals lead us to conclude that the exact genetic contribution of TIA1 to ALS and FTD pathogenesis remains to be further elucidated.

• Klíčová slova
• Amyotrophic lateral sclerosis (ALS), Frontotemporal dementia (FTD), T cell–restricted intracellular antigen-1 gene (TIA1), TAR DNA-Binding protein 43 (TDP-43),
• MeSH
• amyotrofická laterální skleróza genetika   MeSH
• běloši genetika   MeSH
• frekvence genu MeSH
• frontotemporální demence genetika   MeSH
• kohortové studie MeSH
• lidé MeSH
• missense mutace MeSH
• T-buněčný intracelulární antigen 1 genetika   MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• T-buněčný intracelulární antigen 1 MeSH
• TIA1 protein, human MeSH Prohlížeč

TANK-binding kinase 1 (TBK1) loss-of-function (LoF) mutations are known to cause frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS), often combined with memory deficits early in the disease course. We performed targeted resequencing of TBK1 in 1253 early onset Alzheimer's disease (EOAD) patients from 8 European countries to investigate whether pathogenic TBK1 mutations are enriched among patients with clinical diagnosis of EOAD. Variant frequencies were compared against 2117 origin-matched controls. We identified only 1 LoF mutation (p.Thr79del) in a patient clinically diagnosed with Alzheimer's disease and a positive family history of ALS. We did not observe enrichment of rare variants in EOAD patients compared to controls, nor of rare variants affecting NFκB induction. Of 3 common coding variants, rs7486100 showed evidence of association (OR 1.46 [95% CI 1.13-1.9]; p-value 0.01). Homozygous carriers of the risk allele showed reduced expression of TBK1 (p-value 0.03). Our findings are not indicative of a significant role for TBK1 mutations in EOAD. The association between common variants in TBK1, disease risk and reduced TBK1 expression warrants follow-up in FTD/ALS cohorts.

• Klíčová slova
• Early onset Alzheimer's disease, Frontotemporal dementia, Loss-of-function, RNA sequencing, TBK1,
• MeSH
• alely MeSH
• Alzheimerova nemoc genetika   MeSH
• amyotrofická laterální skleróza genetika   MeSH
• frontotemporální demence genetika   MeSH
• genetická variace genetika   MeSH
• genetické asociační studie * MeSH
• heterozygot MeSH
• homozygot MeSH
• kohortové studie MeSH
• lidé středního věku MeSH
• lidé MeSH
• mutace ztráty funkce genetika   MeSH
• protein-serin-threoninkinasy genetika   MeSH
• riziko MeSH
• senioři MeSH
• Check Tag
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Evropa MeSH
• Názvy látek
• protein-serin-threoninkinasy MeSH
• TBK1 protein, human MeSH Prohlížeč

Premature termination codon (PTC) mutations in the ATP-Binding Cassette, Sub-Family A, Member 7 gene (ABCA7) have recently been identified as intermediate-to-high penetrant risk factor for late-onset Alzheimer's disease (LOAD). High variability, however, is observed in downstream ABCA7 mRNA and protein expression, disease penetrance, and onset age, indicative of unknown modifying factors. Here, we investigated the prevalence and disease penetrance of ABCA7 PTC mutations in a large early onset AD (EOAD)-control cohort, and examined the effect on transcript level with comprehensive third-generation long-read sequencing. We characterized the ABCA7 coding sequence with next-generation sequencing in 928 EOAD patients and 980 matched control individuals. With MetaSKAT rare variant association analysis, we observed a fivefold enrichment (p = 0.0004) of PTC mutations in EOAD patients (3%) versus controls (0.6%). Ten novel PTC mutations were only observed in patients, and PTC mutation carriers in general had an increased familial AD load. In addition, we observed nominal risk reducing trends for three common coding variants. Seven PTC mutations were further analyzed using targeted long-read cDNA sequencing on an Oxford Nanopore MinION platform. PTC-containing transcripts for each investigated PTC mutation were observed at varying proportion (5-41% of the total read count), implying incomplete nonsense-mediated mRNA decay (NMD). Furthermore, we distinguished and phased several previously unknown alternative splicing events (up to 30% of transcripts). In conjunction with PTC mutations, several of these novel ABCA7 isoforms have the potential to rescue deleterious PTC effects. In conclusion, ABCA7 PTC mutations play a substantial role in EOAD, warranting genetic screening of ABCA7 in genetically unexplained patients. Long-read cDNA sequencing revealed both varying degrees of NMD and transcript-modifying events, which may influence ABCA7 dosage, disease severity, and may create opportunities for therapeutic interventions in AD.

• Klíčová slova
• ATP-Binding Cassette, Early Onset Alzheimer’s disease, Loss-of-function, Member 7 (ABCA7), Modifier, RNA sequencing, Sub-Family A, Third-generation long-read sequencing,
• MeSH
• ABC transportéry genetika   MeSH
• Alzheimerova nemoc genetika   MeSH
• dospělí MeSH
• genetická predispozice k nemoci * MeSH
• genetické asociační studie MeSH
• jednonukleotidový polymorfismus * MeSH
• lidé středního věku MeSH
• lidé MeSH
• mutace * MeSH
• senioři MeSH
• věk při počátku nemoci MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• ABC transportéry MeSH
• ABCA7 protein, human MeSH Prohlížeč

Rare variants in the phospholipase D3 gene (PLD3) were associated with increased risk for late-onset Alzheimer disease (LOAD). We identified a missense mutation in PLD3 in whole-genome sequence data of a patient with autopsy confirmed Alzheimer disease (AD) and onset age of 50 years. Subsequently, we sequenced PLD3 in a Belgian early-onset Alzheimer disease (EOAD) patient (N = 261) and control (N = 319) cohort, as well as in European EOAD patients (N = 946) and control individuals (N = 1,209) ascertained in different European countries. Overall, we identified 22 rare variants with a minor allele frequency <1%, 20 missense and two splicing mutations. Burden analysis did not provide significant evidence for an enrichment of rare PLD3 variants in EOAD patients in any of the patient/control cohorts. Also, meta-analysis of the PLD3 data, including a published dataset of a German EOAD cohort, was not significant (P = 0.43; OR = 1.53, 95% CI 0.60-3.31). Consequently, our data do not support a role for PLD3 rare variants in the genetic etiology of EOAD in European EOAD patients. Our data corroborate the negative replication data obtained in LOAD studies and therefore a genetic role of PLD3 in AD remains to be demonstrated.

• Klíčová slova
• Alzheimer dementia, EOAD, PLD3, meta-analysis, next-generation sequencing, rare variants,
• MeSH
• alely MeSH
• alternativní sestřih MeSH
• Alzheimerova nemoc epidemiologie   genetika   MeSH
• dospělí MeSH
• exom MeSH
• fosfolipasa D genetika   MeSH
• genetická predispozice k nemoci * MeSH
• genetická variace * MeSH
• kohortové studie MeSH
• lidé středního věku MeSH
• lidé MeSH
• metaanalýza jako téma MeSH
• odds ratio MeSH
• riziko MeSH
• senioři MeSH
• studie případů a kontrol MeSH
• věk při počátku nemoci MeSH
• vysoce účinné nukleotidové sekvenování MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• senioři MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Evropa epidemiologie   MeSH
• Názvy látek
• fosfolipasa D MeSH
• PLD3 protein, human MeSH Prohlížeč

Meta-analysis of existing genome-wide association studies on Alzheimer's disease (AD) showed subgenome-wide association of an intronic variant in the sequestosome 1 (SQSTM1) gene with AD. We performed targeted resequencing of SQSTM1 in Flanders-Belgian AD patients selected to be enriched for a genetic background (n = 435) and geographically matched nonaffected individuals (n = 872) to investigate the role of both common and rare SQSTM1 variants. Results were extended to the European early-onset dementia cohorts (926 early-onset Alzheimer's disease [EOAD] patients and 1476 nonaffected individuals). Of the 61 detected exonic variants in SQSTM1, the majority were rare (n = 57). Rare variant (minor allele frequency <0.01) burden analysis did not reveal an increased frequency of rare variants in EOAD patients in any of the separate study populations nor when meta-analyzing all cohorts. Common variants p.D292= and p.R312= showed nominal association with AD (odds ratiop.D292= = 1.11 [95% confidence interval = 1-1.22], p = 0.04), only when including the Flanders-Belgian cohort in the meta-analysis. We cannot exclude a role of SQSTM1 genetic variability in late-onset AD, but our data indicate that SQSTM1 does not play a major role in the etiology of EOAD.

• Klíčová slova
• Alzheimer's disease, European early-onset dementia consortium, Meta-analysis, Rare variants, SQSTM1/p62,
• MeSH
• adaptorové proteiny signální transdukční genetika   MeSH
• Alzheimerova nemoc epidemiologie   genetika   MeSH
• genetická variace genetika   MeSH
• kohortové studie MeSH
• lidé středního věku MeSH
• lidé MeSH
• metaanalýza jako téma MeSH
• riziko MeSH
• sekvenční analýza DNA MeSH
• sekvestosom 1 MeSH
• senioři MeSH
• Check Tag
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Belgie epidemiologie   MeSH
• Názvy látek
• adaptorové proteiny signální transdukční MeSH
• sekvestosom 1 MeSH
• SQSTM1 protein, human MeSH Prohlížeč