Genetic characterization of patients with frontotemporal dementia and amyotrophic lateral sclerosis in the Nordic countries

Frontotemporal dementia (FTD) is the second most common form of neurodegenerative disease affecting people under the age of 65 years. The general symptoms are dysfunctions in behavior and/or language. Up to 50 % of FTD patients have a positive family history for dementia and mutations in the progranulin (GRN) gene account for 13-25 % of the familial cases. In Paper I, the Swedish Karolinska family with FTD was shown to have a GRN mutation, p.Gly35GlufsX19, which segregated with the disease. The mutation resulted in an ~50 % reduction of the GRN transcript. Sequencing the GRN cDNA resulted in only wild type sequence indicating that the mutant allele had been degraded resulting in reduced GRN transcript levels. GRN mutations have reduced penetrance which is shown e.g. in the Karolinska family where there is a 10 years range in age at onset. The single nucleotide polymorphism (SNP) rs1990622, in linkage disequilibrium with the transmembrane protein 106B (TMEM106B) gene, was suggested to modify age at onset in GRN mutations carriers. In Paper II, the effect of rs1990622 on age at onset in four GRN mutation families, including the Karolinska family was investigated. Patients homozygous for the A allele were shown to have a significantly earlier (13 years) median age at onset compared to patients with the GA or GG genotype. To investigate possible disease mechanisms of rs1990622, the GRN levels in plasma and the TMEM106B mRNA levels in brain tissue were measured. An effect of rs1990622 genotype on plasma-GRN levels was detected with AA carriers having the lowest GRN levels and GG carriers the highest levels. However, this effect was not shown to be mediated by the modulation of TMEM106B transcript levels. In Paper III, 100 FTD patients from Sweden were screened for GRN mutations and four premature stop codon mutations were identified: p.Gly35GlufsX19, p.Cys416LeufsX30, p.Tyr294X and p.Cys404X. Furthermore, the p. Cys416LeufsX30 was shown to segregate in a family with clinical heterogeneity. The serum-GRN levels in carriers of the three first premature stop codons showed a more than 50 % reduction compared to non-carriers. GRN levels and age at onset in the patient cohort varied and were thus investigated for association with rs1990622, rs5848 (located in the 3’UTR of GRN) and apolipoprotein E (APOE). Patients with the TT genotype at rs5848 had significantly lower GRN levels compared to CT and CC genotypes. Moreover, APOE ɛ4 positive patients had a significantly later age at onset compared to ɛ4 negative patients. FTD and amyotrophic lateral sclerosis (ALS) are part of the same disease spectrum. The identification of TAR DNA binding protein 43 (TDP-43) positive neuronal inclusions in the majority of ALS and FTD patients further supported the link. To investigate the importance of TARDBP (the gene encoding TDP-43) mutations in Nordic ALS patients, 177 patients were sequenced in Paper IV. Four missense variations in three familial ALS patients were detected: p.Ala90Val, p.Gly357Arg, p.Arg361Thr and p.Ser379Pro. The three last missense variations were concluded to be possibly pathogenic since they were predicted by in silico analysis to be pathogenic and were absent in 200 neurologically healthy controls. The mutation frequency of TARDBP in Nordic ALS patient was 1.7 %. Furthermore, the p.Arg361Thr was shown to be present in a family with both ALS and FTD-ALS which further strengthens the connection between FTD and ALS

Two-way habitat use between reefs and open ocean in adult greater amberjack: evidence from biologging data

We investigated the relationships between vertical movements and both oceanographic features and physiological factors in greater amberjack Seriola dumerili, which is a reef-associated predator in the East China Sea. S. dumerili in the coastal waters of eastern Taiwan were equipped with archival tags or pop-up satellite archival tags that recorded depth and temperature, resulting in a dataset covering a total of 1331 d from 12 individuals. To classify the vertical movement patterns of S. dumerili, we performed a hierarchical cluster analysis for the depth profile. We observed multiple vertical movement patterns. Around topographic features, S. dumerili showed short-step dives (averaging < 35 m) during both the daytime and nighttime. In contrast, S. dumerili in offshore areas showed diel vertical movements. S. dumerili occasionally performed frequent dives to approximately 150 m throughout the day. These movements may be related to foraging behaviors associated with changes in water depth. We further analyzed the response of the peri-toneal cavity temperature to variations in the ambient temperature in 7 S. dumerili with archival tags. The peritoneal cavity temperatures fluctuated according to the ambient temperature changes, indicating that the vertical movement of S. dumerili is limited by physiological con-straints for the maintenance of body temperature. Together, our results indicate that the vertical movement of S. dumerili may be affected by the trade-off between foraging and thermoregulation

A microfluidic-FCS platform for investigation on the dissociation of Sp1-DNA complex by doxorubicin

The transcription factor (TF) Sp1 is a well-known RNA polymerase II transcription activator that binds to GC-rich recognition sites in a number of essential cellular and viral promoters. In addition, direct interference of Sp1 binding to DNA cognate sites using DNA-interacting compounds may provide promising therapies for suppression of cancer progression and viral replication. In this study, we present a rapid, sensitive and cost-effective evaluation of a GC intercalative drug, doxorubicin (DOX), in dissociating the Sp1–DNA complex using fluorescence correlation spectroscopy (FCS) in a microfluidic system. FCS allows assay miniaturization without compromising sensitivity, making it an ideal analytical method for integration of binding assays into high-throughput, microfluidic platforms. A polydimethylsiloxane (PDMS)-based microfluidic chip with a mixing network is used to achieve specific drug concentrations for drug titration experiments. Using FCS measurements, the IC(50) of DOX on the dissociation of Sp1–DNA complex is estimated to be 0.55 μM, which is comparable to that measured by the electrophoretic mobility shift assay (EMSA). However, completion of one drug titration experiment on the proposed microfluidic-FCS platform is accomplished using only picograms of protein and DNA samples and less than 1 h total assay time, demonstrating vast improvements over traditional ensemble techniques

Rare mutations in SQSTM1 modify susceptibility to frontotemporal lobar degeneration

Mutations in the gene coding for Sequestosome 1 (SQSTM1) have been genetically associated with amyotrophic lateral sclerosis (ALS) and Paget disease of bone. In the present study, we analyzed the SQSTM1 coding sequence for mutations in an extended cohort of 1,808 patients with frontotemporal lobar degeneration (FTLD), ascertained within the European Early-Onset Dementia consortium. As control dataset, we sequenced 1,625 European control individuals and analyzed whole-exome sequence data of 2,274 German individuals (total n = 3,899). Association of rare SQSTM1 mutations was calculated in a meta-analysis of 4,332 FTLD and 10,240 control alleles. We identified 25 coding variants in FTLD patients of which 10 have not been described. Fifteen mutations were absent in the control individuals (carrier frequency < 0.00026) whilst the others were rare in both patients and control individuals. When pooling all variants with a minor allele frequency < 0.01, an overall frequency of 3.2 % was calculated in patients. Rare variant association analysis between patients and controls showed no difference over the whole protein, but suggested that rare mutations clustering in the UBA domain of SQSTM1 may influence disease susceptibility by doubling the risk for FTLD (RR = 2.18 [95 % CI 1.24-3.85]; corrected p value = 0.042). Detailed histopathology demonstrated that mutations in SQSTM1 associate with widespread neuronal and glial phospho-TDP-43 pathology. With this study, we provide further evidence for a putative role of rare mutations in SQSTM1 in the genetic etiology of FTLD and showed that, comparable to other FTLD/ALS genes, SQSTM1 mutations are associated with TDP-43 pathology

Frontotemporal dementia and its subtypes: a genome-wide association study

SummaryBackground Frontotemporal dementia (FTD) is a complex disorder characterised by a broad range of clinical manifestations, differential pathological signatures, and genetic variability. Mutations in three genes—MAPT, GRN, and C9orf72—have been associated with FTD. We sought to identify novel genetic risk loci associated with the disorder. Methods We did a two-stage genome-wide association study on clinical FTD, analysing samples from 3526 patients with {FTD} and 9402 healthy controls. To reduce genetic heterogeneity, all participants were of European ancestry. In the discovery phase (samples from 2154 patients with {FTD} and 4308 controls), we did separate association analyses for each {FTD} subtype (behavioural variant FTD, semantic dementia, progressive non-fluent aphasia, and {FTD} overlapping with motor neuron disease FTD-MND), followed by a meta-analysis of the entire dataset. We carried forward replication of the novel suggestive loci in an independent sample series (samples from 1372 patients and 5094 controls) and then did joint phase and brain expression and methylation quantitative trait loci analyses for the associated (p&lt;5 × 10−8) single-nucleotide polymorphisms. Findings We identified novel associations exceeding the genome-wide significance threshold (p&lt;5 × 10−8). Combined (joint) analyses of discovery and replication phases showed genome-wide significant association at 6p21.3, \{HLA\} locus (immune system), for rs9268877 (p=1·05 × 10−8; odds ratio=1·204 95% \{CI\} 1·11–1·30), rs9268856 (p=5·51 × 10−9; 0·809 0·76–0·86) and rs1980493 (p value=1·57 × 10−8, 0·775 0·69–0·86) in the entire cohort. We also identified a potential novel locus at 11q14, encompassing RAB38/CTSC (the transcripts of which are related to lysosomal biology), for the behavioural \{FTD\} subtype for which joint analyses showed suggestive association for rs302668 (p=2·44 × 10−7; 0·814 0·71–0·92). Analysis of expression and methylation quantitative trait loci data suggested that these loci might affect expression and methylation in cis. Interpretation Our findings suggest that immune system processes (link to 6p21.3) and possibly lysosomal and autophagy pathways (link to 11q14) are potentially involved in FTD. Our findings need to be replicated to better define the association of the newly identified loci with disease and to shed light on the pathomechanisms contributing to FTD. Funding The National Institute of Neurological Disorders and Stroke and National Institute on Aging, the Wellcome/MRC Centre on Parkinson's disease, Alzheimer's Research UK, and Texas Tech University Health Sciences Center