Human prion diseases are rare, transmissible and often rapidly progressive dementias. The most common type, sporadic Creutzfeldt-Jakob disease (sCJD), is highly variable in clinical duration and age at onset. Genetic determinants of late onset or slower progression might suggest new targets for research and therapeutics. We assembled and array genotyped sCJD cases diagnosed in life or at autopsy. Clinical duration (median:4, interquartile range (IQR):2.5-9 (months)) was available in 3,773 and age at onset (median:67, IQR:61-73 (years)) in 3,767 cases. Phenotypes were successfully transformed to approximate normal distributions allowing genome-wide analysis without statistical inflation. 53 SNPs achieved genome-wide significance for the clinical duration phenotype; all of which were located at chromosome 20 (top SNP rs1799990, pvalue = 3.45x10-36, beta = 0.34 for an additive model; rs1799990, pvalue = 9.92x10-67, beta = 0.84 for a heterozygous model). Fine mapping, conditional and expression analysis suggests that the well-known non-synonymous variant at codon 129 is the obvious outstanding genome-wide determinant of clinical duration. Pathway analysis and suggestive loci are described. No genome-wide significant SNP determinants of age at onset were found, but the HS6ST3 gene was significant (pvalue = 1.93 x 10-6) in a gene-based test. We found no evidence of genome-wide genetic correlation between case-control (disease risk factors) and case-only (determinants of phenotypes) studies. Relative to other common genetic variants, PRNP codon 129 is by far the outstanding modifier of CJD survival suggesting only modest or rare variant effects at other genetic loci.
Genetic prion disease accounts for 10–15% of prion disease. While insertion of four or more octapeptide repeats are clearly pathogenic, smaller repeat insertions have an unclear pathogenicity. The goal of this case series was to provide an insight into the characteristics of the 2-octapeptide repeat genetic variant and to provide insight into the risk for Creutzfeldt–Jakob disease in asymptomatic carriers. 2-octapeptide repeat insertion prion disease cases were collected from the National Prion Disease Pathology Surveillance Center (US), the National Prion Clinic (UK), and the National Creutzfeldt–Jakob Disease Registry (Australia). Three largescale population genetic databases were queried for the 2-octapeptide repeat insertion allele. Eight cases of 2-octapeptide repeat insertion were identified. The cases were indistinguishable from the sporadic Creutzfeldt–Jakob cases of the same molecular subtype. Western blot characterization of the prion protein in the absence of enzymatic digestion with proteinase K revealed that 2-octapeptide repeat insertion and sporadic Creutzfeldt–Jakob disease have distinct prion protein profiles. Interrogation of large-scale population datasets suggested the variant is of very low penetrance. The 2-octapeptide repeat insertion is at most a low-risk genetic variant. Predictive genetic testing for asymptomatic blood relatives is not likely to be justified given the low risk.
Mammalian prions are lethal pathogens composed of fibrillar assemblies of misfolded prion protein. Human prion diseases are rare and usually rapidly fatal neurodegenerative disorders, the most common being sporadic Creutzfeldt-Jakob disease (sCJD). Variants in the gene that encodes prion protein ( PRNP ) are strong risk factors for sCJD, but although the condition has heritability similar to other neurodegenerative disorders, no other risk loci have yet been confirmed. By genome-wide association in European ancestry populations, we found three replicated loci (cases n=5208, within PRNP, STX6 , and GAL3ST1 ) and two further unreplicated loci were significant in gene-wide tests (within PDIA4, BMERB1 ). Exome sequencing in 407 sCJD cases, conditional and transcription analyses suggest that associations at PRNP and GAL3ST1 are likely to be caused by common variants that alter the protein sequence, whereas risk variants in STX6 and PDIA4 associate with increased expression of the major transcripts in disease-relevant brain regions. Alteration of STX6 expression does not modify prion propagation in a neuroblastoma cell model of mouse prion infection. We went on to analyse the proteins histologically in diseased tissue and examine the effects of risk variants on clinical phenotypes using deep longitudinal clinical cohort data. Risk SNPs in STX6 , a protein involved in the intracellular trafficking of proteins and vesicles, are shared with progressive supranuclear palsy, a neurodegenerative disease associated with the misfolded protein tau. We present the first evidence of statistically robust associations in sporadic human prion disease that implicate intracellular trafficking and sphingolipid metabolism.
BACKGROUND:Human prion diseases are rare and usually rapidly fatal neurodegenerative disorders, the most common being sporadic Creutzfeldt-Jakob disease (sCJD). Variants in the PRNP gene that encodes prion protein are strong risk factors for sCJD but, although the condition has similar heritability to other neurodegenerative disorders, no other genetic risk loci have been confirmed. We aimed to discover new genetic risk factors for sCJD, and their causal mechanisms. METHODS:We did a genome-wide association study of sCJD in European ancestry populations (patients diagnosed with probable or definite sCJD identified at national CJD referral centres) with a two-stage study design using genotyping arrays and exome sequencing. Conditional, transcriptional, and histological analyses of implicated genes and proteins in brain tissues, and tests of the effects of risk variants on clinical phenotypes, were done using deep longitudinal clinical cohort data. Control data from healthy individuals were obtained from publicly available datasets matched for country. FINDINGS:Samples from 5208 cases were obtained between 1990 and 2014. We found 41 genome-wide significant single nucleotide polymorphisms (SNPs) and independently replicated findings at three loci associated with sCJD risk; within PRNP (rs1799990; additive model odds ratio [OR] 1·23 [95% CI 1·17-1·30], p=2·68 × 10-15; heterozygous model p=1·01 × 10-135), STX6 (rs3747957; OR 1·16 [1·10-1·22], p=9·74 × 10-9), and GAL3ST1 (rs2267161; OR 1·18 [1·12-1·25], p=8·60 × 10-10). Follow-up analyses showed that associations at PRNP and GAL3ST1 are likely to be caused by common variants that alter the protein sequence, whereas risk variants in STX6 are associated with increased expression of the major transcripts in disease-relevant brain regions. INTERPRETATION:We present, to our knowledge, the first evidence of statistically robust genetic associations in sporadic human prion disease that implicate intracellular trafficking and sphingolipid metabolism as molecular causal mechanisms. Risk SNPs in STX6 are shared with progressive supranuclear palsy, a neurodegenerative disease associated with misfolding of protein tau, indicating that sCJD might share the same causal mechanisms as prion-like disorders. FUNDING:Medical Research Council and the UK National Institute of Health Research in part through the Biomedical Research Centre at University College London Hospitals National Health Service Foundation Trust.
BACKGROUND:We characterised the phenotypic consequence of genetic variation at the PCSK9 locus and compared findings with recent trials of pharmacological inhibitors of PCSK9. METHODS:Published and individual participant level data (300,000+ participants) were combined to construct a weighted PCSK9 gene-centric score (GS). Seventeen randomized placebo controlled PCSK9 inhibitor trials were included, providing data on 79,578 participants. Results were scaled to a one mmol/L lower LDL-C concentration. RESULTS:The PCSK9 GS (comprising 4 SNPs) associations with plasma lipid and apolipoprotein levels were consistent in direction with treatment effects. The GS odds ratio (OR) for myocardial infarction (MI) was 0.53 (95% CI 0.42; 0.68), compared to a PCSK9 inhibitor effect of 0.90 (95% CI 0.86; 0.93). For ischemic stroke ORs were 0.84 (95% CI 0.57; 1.22) for the GS, compared to 0.85 (95% CI 0.78; 0.93) in the drug trials. ORs with type 2 diabetes mellitus (T2DM) were 1.29 (95% CI 1.11; 1.50) for the GS, as compared to 1.00 (95% CI 0.96; 1.04) for incident T2DM in PCSK9 inhibitor trials. No genetic associations were observed for cancer, heart failure, atrial fibrillation, chronic obstructive pulmonary disease, or Alzheimer's disease - outcomes for which large-scale trial data were unavailable. CONCLUSIONS:Genetic variation at the PCSK9 locus recapitulates the effects of therapeutic inhibition of PCSK9 on major blood lipid fractions and MI. While indicating an increased risk of T2DM, no other possible safety concerns were shown; although precision was moderate.
Genome-wide association studies have provided evidence for inherited genetic predisposition to chronic lymphocytic leukemia (CLL). To gain insight into the mechanisms underlying CLL risk we analyze chromatin accessibility, active regulatory elements marked by H3K27ac, and DNA methylation at 42 risk loci in up to 486 primary CLLs. We identify that risk loci are significantly enriched for active chromatin in CLL with evidence of being CLL-specific or differentially regulated in normal B-cell development. We then use in situ promoter capture Hi-C, in conjunction with gene expression data to reveal likely target genes of the risk loci. Candidate target genes are enriched for pathways related to B-cell development such as MYC and BCL2 signalling. At 14 loci the analysis highlights 63 variants as the probable functional basis of CLL risk. By integrating genetic and epigenetic information our analysis reveals novel insights into the relationship between inherited predisposition and the regulatory chromatin landscape of CLL.
The clustering of different types of B-cell malignancies in families raises the possibility of shared aetiology. To examine this, we performed cross-trait linkage disequilibrium (LD)-score regression of multiple myeloma (MM) and chronic lymphocytic leukaemia (CLL) genome-wide association study (GWAS) data sets, totalling 11,734 cases and 29,468 controls. A significant genetic correlation between these two B-cell malignancies was shown ( R g = 0.4, P = 0.0046). Furthermore, four of the 45 known CLL risk loci were shown to associate with MM risk and five of the 23 known MM risk loci associate with CLL risk. By integrating eQTL, Hi-C and ChIP-seq data, we show that these pleiotropic risk loci are enriched for B-cell regulatory elements and implicate B-cell developmental genes. These data identify shared biological pathways influencing the development of CLL and, MM and further our understanding of the aetiological basis of these B-cell malignancies.
B-cell malignancies (BCM) originate from the same cell of origin, but at different maturation stages and have distinct clinical phenotypes. Although genetic risk variants for individual BCMs have been identified, an agnostic, genome-wide search for shared genetic susceptibility has not been performed. We explored genome-wide association studies of chronic lymphocytic leukaemia (CLL, N = 1,842), Hodgkin lymphoma (HL, N = 1,465) and multiple myeloma (MM, N = 3,790). We identified a novel pleiotropic risk locus at 3q22.2 (NCK1, rs11715604, P = 1.60 × 10−9) with opposing effects between CLL (P = 1.97 × 10−8) and HL (P = 3.31 × 10−3). Eight established non-HLA risk loci showed pleiotropic associations. Within the HLA region, Ser37 + Phe37 in HLA-DRB1 (P = 1.84 × 10−12) was associated with increased CLL and HL risk (P = 4.68 × 10−12), and reduced MM risk (P = 1.12 × 10−2), and Gly70 in HLA-DQB1 (P = 3.15 × 10−10) showed opposing effects between CLL (P = 3.52 × 10−3) and HL (P = 3.41 × 10−9). By integrating eQTL, Hi-C and ChIP-seq data, we show that the pleiotropic risk loci are enriched for B-cell regulatory elements, as well as an over-representation of binding of key B-cell transcription factors. These data identify shared biological pathways influencing the development of CLL, HL and MM. The identification of these risk loci furthers our understanding of the aetiological basis of BCMs.
Several chronic lymphocytic leukaemia (CLL) susceptibility loci have been reported; however, much of the heritable risk remains unidentified. Here we perform a meta-analysis of six genome-wide association studies, imputed using a merged reference panel of 1,000 Genomes and UK10K data, totalling 6,200 cases and 17,598 controls after replication. We identify nine risk loci at 1p36.11 (rs34676223, P =5.04 × 10 −13 ), 1q42.13 (rs41271473, P =1.06 × 10 −10 ), 4q24 (rs71597109, P =1.37 × 10 −10 ), 4q35.1 (rs57214277, P =3.69 × 10 −8 ), 6p21.31 (rs3800461, P =1.97 × 10 −8 ), 11q23.2 (rs61904987, P =2.64 × 10 −11 ), 18q21.1 (rs1036935, P =3.27 × 10 −8 ), 19p13.3 (rs7254272, P =4.67 × 10 −8 ) and 22q13.33 (rs140522, P =2.70 × 10 −9 ). These new and established risk loci map to areas of active chromatin and show an over-representation of transcription factor binding for the key determinants of B-cell development and immune response.
Chronic lymphocytic leukemia (CLL) can be familial; however, thus far no rare germ line disruptive alleles for CLL have been identified. We performed whole-exome sequencing of 66 CLL families, identifying 4 families where loss-of-function mutations in protection of telomeres 1 (POT1) co-segregated with CLL. The p.Tyr36Cys mutation is predicted to disrupt the interaction between POT1 and the telomeric overhang. The c.1164-1G>A splice-site, p.Gln358SerfsTer13 frameshift, and p.Gln376Arg missense mutations are likely to impact the interaction between POT1 and adrenocortical dysplasia homolog (ACD), which is a part of the telomere-capping shelterin complex. We also identified mutations in ACD (c.752-2A>C) and another shelterin component, telomeric repeat binding factor 2, interacting protein (p.Ala104Pro and p.Arg133Gln), in 3 CLL families. In a complementary analysis of 1083 cases and 5854 controls, the POT1 p.Gln376Arg variant, which has a global minor allele frequency of 0.0005, conferred a 3.61-fold increased risk of CLL (P = .009). This study further highlights telomere dysregulation as a key process in CLL development.
Chronic lymphocytic leukemia (CLL) is an adult B cell malignancy. Genome-wide association studies show that variation at 15q15.1 influences CLL risk. We deciphered the causal variant at 15q15.1 and the mechanism by which it influences tumorigenesis. We imputed all possible genotypes across the locus and then mapped highly associated SNPs to areas of chromatin accessibility, evolutionary conservation, and transcription factor binding. SNP rs539846 C>A, the most highly associated variant (p = 1.42 × 10−13, odds ratio = 1.35), localizes to a super-enhancer defined by extensive histone H3 lysine 27 acetylation in intron 3 of B cell lymphoma 2 (BCL2)-modifying factor (BMF). The rs539846-A risk allele alters a conserved RELA-binding motif, disrupts RELA binding, and is associated with decreased BMF expression in CLL. These findings are consistent with rs539846 influencing CLL susceptibility through differential RELA binding, with direct modulation of BMF expression impacting on anti-apoptotic BCL2, a hallmark of oncogenic dependency in CLL.
Multiple regulatory elements distant from their targets on the linear genome can influence the expression of a single gene through chromatin looping. Chromosome conformation capture implemented in Hi-C allows for genome-wide agnostic characterization of chromatin contacts. However, detection of functional enhancer–promoter interactions is precluded by its effective resolution that is determined by both restriction fragmentation and sensitivity of the experiment. Here we develop a capture Hi-C (cHi-C) approach to allow an agnostic characterization of these physical interactions on a genome-wide scale. Single-nucleotide polymorphisms associated with complex diseases often reside within regulatory elements and exert effects through long-range regulation of gene expression. Applying this cHi-C approach to 14 colorectal cancer risk loci allows us to identify key long-range chromatin interactions in cis and trans involving these loci.
Significance A previously unrecognized role is described for collagen XVIII—a ubiquitous, structurally complex basement membrane proteoglycan—in supporting preadipocyte differentiation and the maintenance of this differentiated state, and hence the size and lipid-clearing/storage functions of white adipose tissue depots. Specific lack of medium and long isoforms of this nonfibrillar collagen in mice led to reduced adiposity, ectopic deposition of fat in liver, and elevated very low-density lipoprotein-triglyceride levels. The finding of a previously unidentified extracellular mechanism contributing to control of adipogenesis is expected to promote understanding of the molecular and functional bases of human hyperlipidemic syndromes associated with fatty liver.
To evaluate the contribution of association studies of candidate polymorphisms to inherited predisposition to chronic lymphocytic leukemia (CLL), we conducted a systematic review and meta-analysis of published case-control studies. We identified 36 studies which reported on polymorphic variation in 19 genes and CLL risk. Out of the 23 polymorphic variants, significant associations (p < 0.05) were seen in pooled analyses for only four variants: MDR1, rs1045642; LTA, rs2239704; CD38, rs6449182; and IFNGR1, rs4896243. These findings should be interpreted cautiously, as the estimated false positive report probabilities (FPRPs) for each association were not noteworthy (i.e. FPRP > 0.2). While studies of candidate polymorphisms may be an attractive means of identifying risk factors for CLL, the limited power of published studies to demonstrate statistically significant associations makes it essential that future analyses be based on sample sizes well-powered to identify variants having modest effects on CLL risk.
The purpose of this study was to determine the core biological processes perturbed in the subcutaneous adipose tissue of familial combined hyperlipidemia (FCHL) patients. Annotation of FCHL and control microarray datasets revealed a distinctive FCHL transcriptome, characterized by gene expression changes regulating five overlapping systems: the cytoskeleton, cell adhesion and extracellular matrix; vesicular trafficking; lipid homeostasis; and cell cycle and apoptosis. Expression values for the cell-cycle inhibitor CDKN2B were increased, replicating data from an independent FCHL cohort. In 3T3-L1 cells, CDKN2B knockdown induced C/EBPα expression and lipid accumulation. The minor allele at SNP site rs1063192 (C) was predicted to create a perfect seed for the human miRNA-323b-5p. A miR-323b-5p mimic significantly reduced endogenous CDKN2B protein levels and the activity of a CDKN2B 3'UTR luciferase reporter carrying the rs1063192 C allele. Although the allele displayed suggestive evidence of association with reduced CDKN2B mRNA in the MuTHER adipose tissue dataset, family studies suggest the association between increased CDKN2B expression and FCHL-lipid abnormalities is driven by factors external to this gene locus. In conclusion, from a comparative annotation analysis of two separate FCHL adipose tissue transcriptomes and a subsequent focus on CDKN2B, we propose that dysfunctional adipogenesis forms an integral part of FCHL pathogenesis.
Richard Houlston and colleagues report results of a genome-wide association study of chronic lymphocytic leukemia. They validate several new susceptibility loci for this disease, including variants near POT1, TERC and TERT. Genome-wide association studies (GWAS) of chronic lymphocytic leukemia (CLL) have shown that common genetic variation contributes to the heritable risk of CLL. To identify additional CLL susceptibility loci, we conducted a GWAS and performed a meta-analysis with a published GWAS totaling 1,739 individuals with CLL (cases) and 5,199 controls with validation in an additional 1,144 cases and 3,151 controls. A combined analysis identified new susceptibility loci mapping to 3q26.2 (rs10936599, P = 1.74 × 10−9), 4q26 (rs6858698, P = 3.07 × 10−9), 6q25.2 (IPCEF1, rs2236256, P = 1.50 × 10−10) and 7q31.33 (POT1, rs17246404, P = 3.40 × 10−8). Additionally, we identified a promising association at 5p15.33 (CLPTM1L, rs31490, P = 1.72 × 10−7) and validated recently reported putative associations at 5p15.33 (TERT, rs10069690, P = 1.12 × 10−10) and 8q22.3 (rs2511714, P = 2.90 × 10−9). These findings provide further insights into the genetic and biological basis of inherited genetic susceptibility to CLL.
SummaryRecent multi‐stage genome‐wide association studies (GWAS) have identified single nucleotide polymorphisms (SNPs) that are robustly associated with chronic lymphocytic leukaemia (CLL) risk. Given that most of these SNPs map to non‐coding regions of the genome, it suggests that the functional basis of many GWAS signals will be through differential gene expression. By referencing publically accessible expression quantitative trait loci (eQTL) data on lymphoblastoid cells lines (LCLs) we have globally demonstrated an association between GWAS P‐values and eQTLs, consistent with much of the variation in CLL risk being defined by variants impacting on gene expression. To explore using eQTL data to select GWAS SNPs for replication, we genotyped rs2072135 (GWAS P‐value = 0·0024, eQTL P‐value = 1·510−19) in five independent case‐control series totalling 1968 cases and 3538 controls. While not attaining statistical significance (combined P‐value = 1 × 10−4), rs2072135 defines a promising risk locus for CLL. Incorporating eQTL information offers an attractive strategy for selecting SNPs from GWAS for validation.
Chronic lymphocytic leukaemia (CLL) is the most common lymphoid malignancy in Western countries, accounting for around a quarter of all leukaemias. Despite a strong familial basis to CLL, with risks in first-degree relatives of CLL cases being increased around sevenfold, the inherited genetic basis of CLL is currently largely unknown. The failure of genetic studies of CLL families to provide support for a major disease-causing locus has suggested a model of susceptibility based on the co-inheritance of multiple low-risk variants, some of which will be common. Recent genome-wide association studies of CLL have vindicated this model of inherited susceptibility to CLL, identifying common variants at multiple independent loci influencing risk. Here we review the evidence for inherited genetic predisposition to CLL and what the currently identified risk loci are telling us about the biology of CLL development.