Publications by authors named "Patrick Sulem"

194 Publications

Large-scale integration of the plasma proteome with genetics and disease.

Nat Genet 2021 12 2;53(12):1712-1721. Epub 2021 Dec 2.

deCODE genetics/Amgen, Inc., Reykjavik, Iceland.

The plasma proteome can help bridge the gap between the genome and diseases. Here we describe genome-wide association studies (GWASs) of plasma protein levels measured with 4,907 aptamers in 35,559 Icelanders. We found 18,084 associations between sequence variants and levels of proteins in plasma (protein quantitative trait loci; pQTL), of which 19% were with rare variants (minor allele frequency (MAF) < 1%). We tested plasma protein levels for association with 373 diseases and other traits and identified 257,490 associations. We integrated pQTL and genetic associations with diseases and other traits and found that 12% of 45,334 lead associations in the GWAS Catalog are with variants in high linkage disequilibrium with pQTL. We identified 938 genes encoding potential drug targets with variants that influence levels of possible biomarkers. Combining proteomics, genomics and transcriptomics, we provide a valuable resource that can be used to improve understanding of disease pathogenesis and to assist with drug discovery and development.
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http://dx.doi.org/10.1038/s41588-021-00978-wDOI Listing
December 2021

A genome-wide meta-analysis uncovers six sequence variants conferring risk of vertigo.

Commun Biol 2021 10 7;4(1):1148. Epub 2021 Oct 7.

deCODE genetics/Amgen Inc., Reykjavik, Iceland.

Vertigo is the leading symptom of vestibular disorders and a major risk factor for falls. In a genome-wide association study of vertigo (N = 48,072, N = 894,541), we uncovered an association with six common sequence variants in individuals of European ancestry, including missense variants in ZNF91, OTOG, OTOGL, and TECTA, and a cis-eQTL for ARMC9. The association of variants in ZNF91, OTOGL, and OTOP1 was driven by an association with benign paroxysmal positional vertigo. Using previous reports of sequence variants associating with age-related hearing impairment and motion sickness, we found eight additional variants that associate with vertigo. Although disorders of the auditory and the vestibular system may co-occur, none of the six genome-wide significant vertigo variants were associated with hearing loss and only one was associated with age-related hearing impairment. Our results uncovered sequence variants associating with vertigo in a genome-wide association study and implicated genes with known roles in inner ear development, maintenance, and disease.
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http://dx.doi.org/10.1038/s42003-021-02673-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8497462PMC
October 2021

Sequence variants in malignant hyperthermia genes in Iceland: classification and actionable findings in a population database.

Eur J Hum Genet 2021 Dec 31;29(12):1819-1824. Epub 2021 Aug 31.

deCODE Genetics/Amgen Inc., Reykjavik, Iceland.

Malignant hyperthermia (MH) susceptibility is a rare life-threatening disorder that occurs upon exposure to a triggering agent. MH is commonly due to protein-altering variants in RYR1 and CACNA1S. The American College of Medical Genetics and Genomics recommends that when pathogenic and likely pathogenic variants in RYR1 and CACNA1S are incidentally found, they should be reported to the carriers. The detection of actionable variants allows the avoidance of exposure to triggering agents during anesthesia. First, we report a 10-year-old Icelandic proband with a suspected MH event, harboring a heterozygous missense variant NM_000540.2:c.6710G>A r.(6710g>a) p.(Cys2237Tyr) in the RYR1 gene that is likely pathogenic. The variant is private to four individuals within a three-generation family and absent from 62,240 whole-genome sequenced (WGS) Icelanders. Haplotype sharing and WGS revealed that the variant occurred as a somatic mosaicism also present in germline of the proband's paternal grandmother. Second, using a set of 62,240 Icelanders with WGS, we assessed the carrier frequency of actionable pathogenic and likely pathogenic variants in RYR1 and CACNA1S. We observed 13 actionable variants in RYR1, based on ClinVar classifications, carried by 43 Icelanders, and no actionable variant in CACNA1S. One in 1450 Icelanders carries an actionable variant for MH. Extensive sequencing allows for better classification and precise dating of variants, and WGS of a large fraction of the population has led to incidental findings of actionable MH genotypes.
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http://dx.doi.org/10.1038/s41431-021-00954-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8633338PMC
December 2021

Large-Scale Screening for Monogenic and Clinically Defined Familial Hypercholesterolemia in Iceland.

Arterioscler Thromb Vasc Biol 2021 10 19;41(10):2616-2628. Epub 2021 Aug 19.

deCODE genetics/Amgen, Inc, Reykjavík, Iceland (E.B., G. Thorgeirsson, A.H., G. Thorleifsson, G.S., S.K., H.J., Aðalbjörg Jónasdóttir, Áslaug Jónasdóttir, A.S., S.G., V.S., B.V.H., D.O.A., I.J., D.F.G., H.H., U.T., P.S., K.S.).

Objective: Familial hypercholesterolemia (FH) is traditionally defined as a monogenic disease characterized by severely elevated LDL-C (low-density lipoprotein cholesterol) levels. In practice, FH is commonly a clinical diagnosis without confirmation of a causative mutation. In this study, we sought to characterize and compare monogenic and clinically defined FH in a large sample of Icelanders. Approach and Results: We whole-genome sequenced 49 962 Icelanders and imputed the identified variants into an overall sample of 166 281 chip-genotyped Icelanders. We identified 20 FH mutations in LDLR, APOB, and PCSK9 with combined prevalence of 1 in 836. Monogenic FH was associated with severely elevated LDL-C levels and increased risk of premature coronary disease, aortic valve stenosis, and high burden of coronary atherosclerosis. We used a modified version of the Dutch Lipid Clinic Network criteria to screen for the clinical FH phenotype among living adult participants (N=79 058). Clinical FH was found in 2.2% of participants, of whom only 5.2% had monogenic FH. Mutation-negative clinical FH has a strong polygenic basis. Both individuals with monogenic FH and individuals with mutation-negative clinical FH were markedly undertreated with cholesterol-lowering medications and only a minority attained an LDL-C target of <2.6 mmol/L (<100 mg/dL; 11.0% and 24.9%, respectively) or <1.8 mmol/L (<70 mg/dL; 0.0% and 5.2%, respectively), as recommended for primary prevention by European Society of Cardiology/European Atherosclerosis Society cholesterol guidelines. Conclusions: Clinically defined FH is a relatively common phenotype that is explained by monogenic FH in only a minority of cases. Both monogenic and clinical FH confer high cardiovascular risk but are markedly undertreated.
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http://dx.doi.org/10.1161/ATVBAHA.120.315904DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8454500PMC
October 2021

Genetic insights into biological mechanisms governing human ovarian ageing.

Nature 2021 08 4;596(7872):393-397. Epub 2021 Aug 4.

Genome Integrity and Instability Group, Institut de Biotecnologia i Biomedicina, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Spain.

Reproductive longevity is essential for fertility and influences healthy ageing in women, but insights into its underlying biological mechanisms and treatments to preserve it are limited. Here we identify 290 genetic determinants of ovarian ageing, assessed using normal variation in age at natural menopause (ANM) in about 200,000 women of European ancestry. These common alleles were associated with clinical extremes of ANM; women in the top 1% of genetic susceptibility have an equivalent risk of premature ovarian insufficiency to those carrying monogenic FMR1 premutations. The identified loci implicate a broad range of DNA damage response (DDR) processes and include loss-of-function variants in key DDR-associated genes. Integration with experimental models demonstrates that these DDR processes act across the life-course to shape the ovarian reserve and its rate of depletion. Furthermore, we demonstrate that experimental manipulation of DDR pathways highlighted by human genetics increases fertility and extends reproductive life in mice. Causal inference analyses using the identified genetic variants indicate that extending reproductive life in women improves bone health and reduces risk of type 2 diabetes, but increases the risk of hormone-sensitive cancers. These findings provide insight into the mechanisms that govern ovarian ageing, when they act, and how they might be targeted by therapeutic approaches to extend fertility and prevent disease.
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http://dx.doi.org/10.1038/s41586-021-03779-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7611832PMC
August 2021

Predicting the probability of death using proteomics.

Commun Biol 2021 06 18;4(1):758. Epub 2021 Jun 18.

deCODE Genetics/Amgen, Inc., Reykjavik, Iceland.

Predicting all-cause mortality risk is challenging and requires extensive medical data. Recently, large-scale proteomics datasets have proven useful for predicting health-related outcomes. Here, we use measurements of levels of 4,684 plasma proteins in 22,913 Icelanders to develop all-cause mortality predictors both for short- and long-term risk. The participants were 18-101 years old with a mean follow up of 13.7 (sd. 4.7) years. During the study period, 7,061 participants died. Our proposed predictor outperformed, in survival prediction, a predictor based on conventional mortality risk factors. We could identify the 5% at highest risk in a group of 60-80 years old, where 88% died within ten years and 5% at the lowest risk where only 1% died. Furthermore, the predicted risk of death correlates with measures of frailty in an independent dataset. Our results show that the plasma proteome can be used to assess general health and estimate the risk of death.
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http://dx.doi.org/10.1038/s42003-021-02289-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8213855PMC
June 2021

Molecular benchmarks of a SARS-CoV-2 epidemic.

Nat Commun 2021 06 15;12(1):3633. Epub 2021 Jun 15.

deCODE genetics/Amgen, Inc., Reykjavik, Iceland.

A pressing concern in the SARS-CoV-2 epidemic and other viral outbreaks, is the extent to which the containment measures are halting the viral spread. A straightforward way to assess this is to tally the active cases and the recovered ones throughout the epidemic. Here, we show how epidemic control can be assessed with molecular information during a well characterized epidemic in Iceland. We demonstrate how the viral concentration decreased in those newly diagnosed as the epidemic transitioned from exponential growth phase to containment phase. The viral concentration in the cases identified in population screening decreased faster than in those symptomatic and considered at high risk and that were targeted by the healthcare system. The viral concentration persists in recovering individuals as we found that half of the cases are still positive after two weeks. We demonstrate that accumulation of mutations in SARS-CoV-2 genome can be exploited to track the rate of new viral generations throughout the different phases of the epidemic, where the accumulation of mutations decreases as the transmission rate decreases in the containment phase. Overall, the molecular signatures of SARS-CoV-2 infections contain valuable epidemiological information that can be used to assess the effectiveness of containment measures.
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http://dx.doi.org/10.1038/s41467-021-23883-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8206085PMC
June 2021

The genetic architecture of age-related hearing impairment revealed by genome-wide association analysis.

Commun Biol 2021 06 9;4(1):706. Epub 2021 Jun 9.

deCODE Genetics/Amgen, Reykjavik, Iceland.

Age-related hearing impairment (ARHI) is the most common sensory disorder in older adults. We conducted a genome-wide association meta-analysis of 121,934 ARHI cases and 591,699 controls from Iceland and the UK. We identified 21 novel sequence variants, of which 13 are rare, under either additive or recessive models. Of special interest are a missense variant in LOXHD1 (MAF = 1.96%) and a tandem duplication in FBF1 covering 4 exons (MAF = 0.22%) associating with ARHI (OR = 3.7 for homozygotes, P = 1.7 × 10 and OR = 4.2 for heterozygotes, P = 5.7 × 10, respectively). We constructed an ARHI genetic risk score (GRS) using common variants and showed that a common variant GRS can identify individuals at risk comparable to carriers of rare high penetrance variants. Furthermore, we found that ARHI and tinnitus share genetic causes. This study sheds a new light on the genetic architecture of ARHI, through several rare variants in both Mendelian deafness genes and genes not previously linked to hearing.
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http://dx.doi.org/10.1038/s42003-021-02224-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8190123PMC
June 2021

The CRTAC1 Protein in Plasma Is Associated With Osteoarthritis and Predicts Progression to Joint Replacement: A Large-Scale Proteomics Scan in Iceland.

Arthritis Rheumatol 2021 11 28;73(11):2025-2034. Epub 2021 Sep 28.

deCODE Genetics, Inc., and University of Iceland, Reykjavik, Iceland.

Objective: Biomarkers for diagnosis and progression of osteoarthritis (OA) are lacking. This study was undertaken to identify circulating biomarkers for OA that could predict disease occurrence and/or progression to joint replacement.

Methods: Using the SomaScan platform, we measured 4,792 proteins in plasma from 37,278 individuals, of whom 12,178 individuals had OA and 2,524 had undergone joint replacement. We performed a case-control study for identification of potential protein biomarkers for hip, knee, and/or hand OA, and a prospective study for identification of biomarkers for joint replacement.

Results: Among the large panel of plasma proteins assessed, cartilage acidic protein 1 (CRTAC1) was the most strongly associated with both OA diagnosis (odds ratio 1.46 [95% confidence interval 1.41-1.52] for knee OA, odds ratio 1.36 [95% confidence interval 1.29-1.43] for hip OA, and odds ratio 1.33 [95% confidence interval 1.26-1.40] for hand OA) and progression to joint replacement (hazard ratio 1.40 [95% confidence interval 1.30-1.51] for knee replacement and hazard ratio 1.31 [95% confidence interval 1.19-1.45] for hip replacement). Patients with OA who were in the highest quintile of risk of joint replacement, based on known risk factors (i.e., age, sex, and body mass index) and plasma CRTAC1 level, were 16 times more likely to undergo knee replacement within 5 years of plasma sample collection than those in the lowest quintile, and 6.5 times more likely to undergo hip replacement. CRTAC1 was not associated with other types of inflammatory arthritis. A specific protein profile was identified in those patients who had undergone joint replacement prior to plasma sample collection.

Conclusion: Through a hypothesis-free approach, we identified CRTAC1 in plasma as a novel promising candidate biomarker for OA that is both associated with occurrence of OA and predictive of progression to joint replacement. This biomarker might also be useful in the selection of suitable patients for clinical trial enrollment.
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http://dx.doi.org/10.1002/art.41793DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8596997PMC
November 2021

Long-read sequencing of 3,622 Icelanders provides insight into the role of structural variants in human diseases and other traits.

Nat Genet 2021 06 10;53(6):779-786. Epub 2021 May 10.

deCODE genetics/Amgen, Inc., Reykjavik, Iceland.

Long-read sequencing (LRS) promises to improve the characterization of structural variants (SVs). We generated LRS data from 3,622 Icelanders and identified a median of 22,636 SVs per individual (a median of 13,353 insertions and 9,474 deletions). We discovered a set of 133,886 reliably genotyped SV alleles and imputed them into 166,281 individuals to explore their effects on diseases and other traits. We discovered an association of a rare deletion in PCSK9 with lower low-density lipoprotein (LDL) cholesterol levels, compared to the population average. We also discovered an association of a multiallelic SV in ACAN with height; we found 11 alleles that differed in the number of a 57-bp-motif repeat and observed a linear relationship between the number of repeats carried and height. These results show that SVs can be accurately characterized at the population scale using LRS data in a genome-wide non-targeted approach and demonstrate how SVs impact phenotypes.
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http://dx.doi.org/10.1038/s41588-021-00865-4DOI Listing
June 2021

Allele frequency of variants reported to cause adenine phosphoribosyltransferase deficiency.

Eur J Hum Genet 2021 07 11;29(7):1061-1070. Epub 2021 Mar 11.

Faculty of Medicine, School of Health Sciences, University of Iceland, Reykjavik, Iceland.

Adenine phosphoribosyltransferase deficiency is a rare, autosomal recessive disorder of purine metabolism that causes nephrolithiasis and progressive chronic kidney disease. The small number of reported cases indicates an extremely low prevalence, although it has been suggested that missed diagnoses may play a role. We assessed the prevalence of APRT deficiency based on the frequency of causally-related APRT sequence variants in a diverse set of large genomic databases. A thorough search was carried out for all APRT variants that have been confirmed as pathogenic under recessive mode of inheritance, and the frequency of the identified variants examined in six population genomic databases: the deCODE genetics database, the UK Biobank, the 100,000 Genomes Project, the Genome Aggregation Database, the Human Genetic Variation Database and the Korean Variant Archive. The estimated frequency of homozygous genotypes was calculated using the Hardy-Weinberg equation. Sixty-two pathogenic APRT variants were identified, including six novel variants. Most common were the missense variants c.407T>C (p.(Met136Thr)) in Japan and c.194A>T (p.(Asp65Val)) in Iceland, as well as the splice-site variant c.400 + 2dup (p.(Ala108Glufs*3)) in the European population. Twenty-nine variants were detected in at least one of the six genomic databases. The highest cumulative minor allele frequency (cMAF) of pathogenic variants outside of Japan and Iceland was observed in the Irish population (0.2%), though no APRT deficiency cases have been reported in Ireland. The large number of cases in Japan and Iceland is consistent with a founder effect in these populations. There is no evidence for widespread underdiagnosis based on the current analysis.
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http://dx.doi.org/10.1038/s41431-020-00805-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8298615PMC
July 2021

Loss-of-Function Variants in the Tumor-Suppressor Gene Confer Increased Cancer Risk.

Cancer Res 2021 04 18;81(8):1954-1964. Epub 2021 Feb 18.

deCODE Genetics/Amgen, Reykjavik, Iceland.

The success of genome-wide association studies (GWAS) in identifying common, low-penetrance variant-cancer associations for the past decade is undisputed. However, discovering additional high-penetrance cancer mutations in unknown cancer predisposing genes requires detection of variant-cancer association of ultra-rare coding variants. Consequently, large-scale next-generation sequence data with associated phenotype information are needed. Here, we used genotype data on 166,281 Icelanders, of which, 49,708 were whole-genome sequenced and 408,595 individuals from the UK Biobank, of which, 41,147 were whole-exome sequenced, to test for association between loss-of-function burden in autosomal genes and basal cell carcinoma (BCC), the most common cancer in Caucasians. A total of 25,205 BCC cases and 683,058 controls were tested. Rare germline loss-of-function variants in conferred substantial risks of BCC (OR, 8.0; = 1.9 × 10), with a quarter of carriers getting BCC before age 70 and over half in their lifetime. Furthermore, common variants at the locus were associated with BCC, suggesting as a new, high-impact BCC predisposition gene. A follow-up investigation of 24 cancers and three benign tumor types showed that loss-of-function variants are associated with high risk of cervical cancer (OR, 12.7, = 1.6 × 10) and low age at diagnosis. Our findings, using power-increasing methods with high-quality rare variant genotypes, highlight future prospects for new discoveries on carcinogenesis. SIGNIFICANCE: This study identifies the tumor-suppressor gene as a high-impact BCC predisposition gene and indicates that inactivation of by germline sequence variants may also lead to increased risk of cervical cancer.
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http://dx.doi.org/10.1158/0008-5472.CAN-20-3065DOI Listing
April 2021

Genetic insight into sick sinus syndrome.

Eur Heart J 2021 05;42(20):1959-1971

deCODE genetics/Amgen, Inc., Sturlugata 8, Reykjavik 101, Iceland.

Aims: The aim of this study was to use human genetics to investigate the pathogenesis of sick sinus syndrome (SSS) and the role of risk factors in its development.

Methods And Results: We performed a genome-wide association study of 6469 SSS cases and 1 000 187 controls from deCODE genetics, the Copenhagen Hospital Biobank, UK Biobank, and the HUNT study. Variants at six loci associated with SSS, a reported missense variant in MYH6, known atrial fibrillation (AF)/electrocardiogram variants at PITX2, ZFHX3, TTN/CCDC141, and SCN10A and a low-frequency (MAF = 1.1-1.8%) missense variant, p.Gly62Cys in KRT8 encoding the intermediate filament protein keratin 8. A full genotypic model best described the p.Gly62Cys association (P = 1.6 × 10-20), with an odds ratio (OR) of 1.44 for heterozygotes and a disproportionally large OR of 13.99 for homozygotes. All the SSS variants increased the risk of pacemaker implantation. Their association with AF varied and p.Gly62Cys was the only variant not associating with any other arrhythmia or cardiovascular disease. We tested 17 exposure phenotypes in polygenic score (PGS) and Mendelian randomization analyses. Only two associated with the risk of SSS in Mendelian randomization, AF, and lower heart rate, suggesting causality. Powerful PGS analyses provided convincing evidence against causal associations for body mass index, cholesterol, triglycerides, and type 2 diabetes (P > 0.05).

Conclusion: We report the associations of variants at six loci with SSS, including a missense variant in KRT8 that confers high risk in homozygotes and points to a mechanism specific to SSS development. Mendelian randomization supports a causal role for AF in the development of SSS.
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http://dx.doi.org/10.1093/eurheartj/ehaa1108DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8140484PMC
May 2021

A genome-wide meta-analysis yields 46 new loci associating with biomarkers of iron homeostasis.

Commun Biol 2021 02 3;4(1):156. Epub 2021 Feb 3.

deCODE genetics/Amgen Inc., Reykjavik, Iceland.

Iron is essential for many biological functions and iron deficiency and overload have major health implications. We performed a meta-analysis of three genome-wide association studies from Iceland, the UK and Denmark of blood levels of ferritin (N = 246,139), total iron binding capacity (N = 135,430), iron (N = 163,511) and transferrin saturation (N = 131,471). We found 62 independent sequence variants associating with iron homeostasis parameters at 56 loci, including 46 novel loci. Variants at DUOX2, F5, SLC11A2 and TMPRSS6 associate with iron deficiency anemia, while variants at TF, HFE, TFR2 and TMPRSS6 associate with iron overload. A HBS1L-MYB intergenic region variant associates both with increased risk of iron overload and reduced risk of iron deficiency anemia. The DUOX2 missense variant is present in 14% of the population, associates with all iron homeostasis biomarkers, and increases the risk of iron deficiency anemia by 29%. The associations implicate proteins contributing to the main physiological processes involved in iron homeostasis: iron sensing and storage, inflammation, absorption of iron from the gut, iron recycling, erythropoiesis and bleeding/menstruation.
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http://dx.doi.org/10.1038/s42003-020-01575-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7859200PMC
February 2021

PopDel identifies medium-size deletions simultaneously in tens of thousands of genomes.

Nat Commun 2021 02 1;12(1):730. Epub 2021 Feb 1.

Regensburg Center for Interventional Immunology (RCI), Regensburg, Germany.

Thousands of genomic structural variants (SVs) segregate in the human population and can impact phenotypic traits and diseases. Their identification in whole-genome sequence data of large cohorts is a major computational challenge. Most current approaches identify SVs in single genomes and afterwards merge the identified variants into a joint call set across many genomes. We describe the approach PopDel, which directly identifies deletions of about 500 to at least 10,000 bp in length in data of many genomes jointly, eliminating the need for subsequent variant merging. PopDel scales to tens of thousands of genomes as we demonstrate in evaluations on up to 49,962 genomes. We show that PopDel reliably reports common, rare and de novo deletions. On genomes with available high-confidence reference call sets PopDel shows excellent recall and precision. Genotype inheritance patterns in up to 6794 trios indicate that genotypes predicted by PopDel are more reliable than those of previous SV callers. Furthermore, PopDel's running time is competitive with the fastest tested previous tools. The demonstrated scalability and accuracy of PopDel enables routine scans for deletions in large-scale sequencing studies.
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http://dx.doi.org/10.1038/s41467-020-20850-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7851401PMC
February 2021

Differences between germline genomes of monozygotic twins.

Nat Genet 2021 01 7;53(1):27-34. Epub 2021 Jan 7.

deCODE genetics/Amgen, Reykjavik, Iceland.

Despite the important role that monozygotic twins have played in genetics research, little is known about their genomic differences. Here we show that monozygotic twins differ on average by 5.2 early developmental mutations and that approximately 15% of monozygotic twins have a substantial number of these early developmental mutations specific to one of them. Using the parents and offspring of twins, we identified pre-twinning mutations. We observed instances where a twin was formed from a single cell lineage in the pre-twinning cell mass and instances where a twin was formed from several cell lineages. CpG>TpG mutations increased in frequency with embryonic development, coinciding with an increase in DNA methylation. Our results indicate that allocations of cells during development shapes genomic differences between monozygotic twins.
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http://dx.doi.org/10.1038/s41588-020-00755-1DOI Listing
January 2021

Lifelong Reduction in LDL (Low-Density Lipoprotein) Cholesterol due to a Gain-of-Function Mutation in .

Circ Genom Precis Med 2021 02 14;14(1):e003029. Epub 2020 Dec 14.

deCODE genetics/Amgen, Inc (E.B., K.G., G.H.H., A.S., G.A.A., H.J., G.S., S.G., A.H., G. Thorleifsson, J.S., I.J., O.T.M., G.M., H.S., D.F.G., G. Thorgeirsson, H.H., B.V.H., P.M., G.L.N., P.S., U.T., K.S.), University of Iceland.

Background: Loss-of-function mutations in the LDL (low-density lipoprotein) receptor gene () cause elevated levels of LDL cholesterol and premature cardiovascular disease. To date, a gain-of-function mutation in with a large effect on LDL cholesterol levels has not been described. Here, we searched for sequence variants in that have a large effect on LDL cholesterol levels.

Methods: We analyzed whole-genome sequencing data from 43 202 Icelanders. Single-nucleotide polymorphisms and structural variants including deletions, insertions, and duplications were genotyped using whole-genome sequencing-based data. LDL cholesterol associations were carried out in a sample of >100 000 Icelanders with genetic information (imputed or whole-genome sequencing). Molecular analyses were performed using RNA sequencing and protein expression assays in Epstein-Barr virus-transformed lymphocytes.

Results: We discovered a 2.5-kb deletion (del2.5) overlapping the 3' untranslated region of in 7 heterozygous carriers from a single family. Mean level of LDL cholesterol was 74% lower in del2.5 carriers than in 101 851 noncarriers, a difference of 2.48 mmol/L (96 mg/dL; =8.4×10). Del2.5 results in production of an alternative mRNA isoform with a truncated 3' untranslated region. The truncation leads to a loss of target sites for microRNAs known to repress translation of . In Epstein-Barr virus-transformed lymphocytes derived from del2.5 carriers, expression of alternative mRNA isoform was 1.84-fold higher than the wild-type isoform (=0.0013), and there was 1.79-fold higher surface expression of the LDL receptor than in noncarriers (=0.0086). We did not find a highly penetrant detrimental impact of lifelong very low levels of LDL cholesterol due to del2.5 on health of the carriers.

Conclusions: Del2.5 is the first reported gain-of-function mutation in causing a large reduction in LDL cholesterol. These data point to a role for alternative polyadenylation of mRNA as a potent regulator of LDL receptor expression in humans.
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http://dx.doi.org/10.1161/CIRCGEN.120.003029DOI Listing
February 2021

Discovery of rare variants associated with blood pressure regulation through meta-analysis of 1.3 million individuals.

Nat Genet 2020 12 23;52(12):1314-1332. Epub 2020 Nov 23.

Department of Clinical Biochemistry, Herlev and Gentofte Hospital, Copenhagen University Hospital, Herlev, Denmark.

Genetic studies of blood pressure (BP) to date have mainly analyzed common variants (minor allele frequency > 0.05). In a meta-analysis of up to ~1.3 million participants, we discovered 106 new BP-associated genomic regions and 87 rare (minor allele frequency ≤ 0.01) variant BP associations (P < 5 × 10), of which 32 were in new BP-associated loci and 55 were independent BP-associated single-nucleotide variants within known BP-associated regions. Average effects of rare variants (44% coding) were ~8 times larger than common variant effects and indicate potential candidate causal genes at new and known loci (for example, GATA5 and PLCB3). BP-associated variants (including rare and common) were enriched in regions of active chromatin in fetal tissues, potentially linking fetal development with BP regulation in later life. Multivariable Mendelian randomization suggested possible inverse effects of elevated systolic and diastolic BP on large artery stroke. Our study demonstrates the utility of rare-variant analyses for identifying candidate genes and the results highlight potential therapeutic targets.
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http://dx.doi.org/10.1038/s41588-020-00713-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7610439PMC
December 2020

Sequence Variants in TAAR5 and Other Loci Affect Human Odor Perception and Naming.

Curr Biol 2020 12 8;30(23):4643-4653.e3. Epub 2020 Oct 8.

deCODE Genetics/Amgen Inc., Sturlugata 8, 101 Reykjavik, Iceland; Faculty of Medicine, University of Iceland, Vatnsmyrarvegur 16, 101 Reykjavik, Iceland. Electronic address:

Olfactory receptor (OR) genes in humans form a special class characterized by unusually high DNA sequence diversity, which should give rise to differences in perception and behavior. In the largest genome-wide association study to date based on olfactory testing, we investigated odor perception and naming with smell tasks performed by 9,122 Icelanders, with replication in a separate sample of 2,204 individuals. We discovered an association between a low-frequency missense variant in TAAR5 and reduced intensity rating of fish odor containing trimethylamine (p.Ser95Pro, p = 5.6 × 10). We demonstrate that TAAR5 genotype affects aversion to fish odor, reflected by linguistic descriptions of the odor and pleasantness ratings. We also discovered common sequence variants in two canonical olfactory receptor loci that associate with increased intensity and naming of licorice odor (trans-anethole: lead variant p.Lys233Asn in OR6C70, p = 8.8 × 10 and p = 1.4 × 10) and enhanced naming of cinnamon (trans-cinnamaldehyde; intergenic variant rs317787-T, p = 5.0 × 10). Together, our results show that TAAR5 genotype variation influences human odor responses and highlight that sequence diversity in canonical OR genes can lead to enhanced olfactory ability, in contrast to the view that greater tolerance for mutations in the human OR repertoire leads to diminished function.
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http://dx.doi.org/10.1016/j.cub.2020.09.012DOI Listing
December 2020

Humoral Immune Response to SARS-CoV-2 in Iceland.

N Engl J Med 2020 10 1;383(18):1724-1734. Epub 2020 Sep 1.

From deCODE Genetics/Amgen (D.F.G., G.L.N., P.M., K.G., H.H., A.O.A., K. Bjarnadottir, B. Thorsteinsdottir, S.K., K. Birgisdottir, A.M.K., G.A.A., E.V.I., M.A., F.J., A.B.A., J.B., B.E., R.F., E.E.G., S.G., K.R.G., A.G., A.H., B.O.J., A.J., H.J., T.K., D.N.M., O.T.M., S.R., L.R., A.S., G. Sveinbjornsson, K.E.S., E.A.T., B. Thorbjornsson, J.S., G.M., G.G., U.T., I.J., P.S., K.S.), the School of Engineering and Natural Sciences (D.F.G., P.M.), the Department of Anthropology (A.H.), the BioMedical Center (K.G.K.), and the Faculty of Medicine, School of Health Sciences (M.I.S., M.G., K.G.K., R.P., U.T., I.J., K.S.), University of Iceland, Internal Medicine and Rehabilitation Services (E.E., D.H., R.F.I., M.G., L.B.O., M.K., R.P.), the Division of Anesthesia and Intensive Care Medicine (M.I.S.), and the Department of Clinical Microbiology (O.S.G., T.R.G., K.G.K., M.S.), Landspitali-the National University Hospital, and the Directorate of Health (G. Sigmundsdottir, M.T., K.S.J., A.M., T.G.), Reykjavik, and the Health Care Institution of South Iceland, Selfoss (S.H.K.) - all in Iceland.

Background: Little is known about the nature and durability of the humoral immune response to infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

Methods: We measured antibodies in serum samples from 30,576 persons in Iceland, using six assays (including two pan-immunoglobulin [pan-Ig] assays), and we determined that the appropriate measure of seropositivity was a positive result with both pan-Ig assays. We tested 2102 samples collected from 1237 persons up to 4 months after diagnosis by a quantitative polymerase-chain-reaction (qPCR) assay. We measured antibodies in 4222 quarantined persons who had been exposed to SARS-CoV-2 and in 23,452 persons not known to have been exposed.

Results: Of the 1797 persons who had recovered from SARS-CoV-2 infection, 1107 of the 1215 who were tested (91.1%) were seropositive; antiviral antibody titers assayed by two pan-Ig assays increased during 2 months after diagnosis by qPCR and remained on a plateau for the remainder of the study. Of quarantined persons, 2.3% were seropositive; of those with unknown exposure, 0.3% were positive. We estimate that 0.9% of Icelanders were infected with SARS-CoV-2 and that the infection was fatal in 0.3%. We also estimate that 56% of all SARS-CoV-2 infections in Iceland had been diagnosed with qPCR, 14% had occurred in quarantined persons who had not been tested with qPCR (or who had not received a positive result, if tested), and 30% had occurred in persons outside quarantine and not tested with qPCR.

Conclusions: Our results indicate that antiviral antibodies against SARS-CoV-2 did not decline within 4 months after diagnosis. We estimate that the risk of death from infection was 0.3% and that 44% of persons infected with SARS-CoV-2 in Iceland were not diagnosed by qPCR.
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http://dx.doi.org/10.1056/NEJMoa2026116DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7494247PMC
October 2020

Genetic variability in the absorption of dietary sterols affects the risk of coronary artery disease.

Eur Heart J 2020 07;41(28):2618-2628

Laekning, Medical Clinics, Lágmúli 5, 108 Reykjavik, Iceland.

Aims: To explore whether variability in dietary cholesterol and phytosterol absorption impacts the risk of coronary artery disease (CAD) using as instruments sequence variants in the ABCG5/8 genes, key regulators of intestinal absorption of dietary sterols.

Methods And Results: We examined the effects of ABCG5/8 variants on non-high-density lipoprotein (non-HDL) cholesterol (N up to 610 532) and phytosterol levels (N = 3039) and the risk of CAD in Iceland, Denmark, and the UK Biobank (105 490 cases and 844 025 controls). We used genetic scores for non-HDL cholesterol to determine whether ABCG5/8 variants confer greater risk of CAD than predicted by their effect on non-HDL cholesterol. We identified nine rare ABCG5/8 coding variants with substantial impact on non-HDL cholesterol. Carriers have elevated phytosterol levels and are at increased risk of CAD. Consistent with impact on ABCG5/8 transporter function in hepatocytes, eight rare ABCG5/8 variants associate with gallstones. A genetic score of ABCG5/8 variants predicting 1 mmol/L increase in non-HDL cholesterol associates with two-fold increase in CAD risk [odds ratio (OR) = 2.01, 95% confidence interval (CI) 1.75-2.31, P = 9.8 × 10-23] compared with a 54% increase in CAD risk (OR = 1.54, 95% CI 1.49-1.59, P = 1.1 × 10-154) associated with a score of other non-HDL cholesterol variants predicting the same increase in non-HDL cholesterol (P for difference in effects = 2.4 × 10-4).

Conclusions: Genetic variation in cholesterol absorption affects levels of circulating non-HDL cholesterol and risk of CAD. Our results indicate that both dietary cholesterol and phytosterols contribute directly to atherogenesis.
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http://dx.doi.org/10.1093/eurheartj/ehaa531DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7377579PMC
July 2020

FLT3 stop mutation increases FLT3 ligand level and risk of autoimmune thyroid disease.

Nature 2020 08 24;584(7822):619-623. Epub 2020 Jun 24.

Department of Clinical Neuroscience, Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden.

Autoimmune thyroid disease is the most common autoimmune disease and is highly heritable. Here, by using a genome-wide association study of 30,234 cases and 725,172 controls from Iceland and the UK Biobank, we find 99 sequence variants at 93 loci, of which 84 variants are previously unreported. A low-frequency (1.36%) intronic variant in FLT3 (rs76428106-C) has the largest effect on risk of autoimmune thyroid disease (odds ratio (OR) = 1.46, P = 2.37 × 10). rs76428106-C is also associated with systemic lupus erythematosus (OR = 1.90, P = 6.46 × 10), rheumatoid factor and/or anti-CCP-positive rheumatoid arthritis (OR = 1.41, P = 4.31 × 10) and coeliac disease (OR = 1.62, P = 1.20 × 10). FLT3 encodes fms-related tyrosine kinase 3, a receptor that regulates haematopoietic progenitor and dendritic cells. RNA sequencing revealed that rs76428106-C generates a cryptic splice site, which introduces a stop codon in 30% of transcripts that are predicted to encode a truncated protein, which lacks its tyrosine kinase domains. Each copy of rs76428106-C doubles the plasma levels of the FTL3 ligand. Activating somatic mutations in FLT3 are associated with acute myeloid leukaemia with a poor prognosis and rs76428106-C also predisposes individuals to acute myeloid leukaemia (OR = 1.90, P = 5.40 × 10). Thus, a predicted loss-of-function germline mutation in FLT3 causes a reduction in full-length FLT3, with a compensatory increase in the levels of its ligand and an increased disease risk, similar to that of a gain-of-function mutation.
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http://dx.doi.org/10.1038/s41586-020-2436-0DOI Listing
August 2020

Multi-ancestry GWAS of the electrocardiographic PR interval identifies 202 loci underlying cardiac conduction.

Nat Commun 2020 05 21;11(1):2542. Epub 2020 May 21.

Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK.

The electrocardiographic PR interval reflects atrioventricular conduction, and is associated with conduction abnormalities, pacemaker implantation, atrial fibrillation (AF), and cardiovascular mortality. Here we report a multi-ancestry (N = 293,051) genome-wide association meta-analysis for the PR interval, discovering 202 loci of which 141 have not previously been reported. Variants at identified loci increase the percentage of heritability explained, from 33.5% to 62.6%. We observe enrichment for cardiac muscle developmental/contractile and cytoskeletal genes, highlighting key regulation processes for atrioventricular conduction. Additionally, 8 loci not previously reported harbor genes underlying inherited arrhythmic syndromes and/or cardiomyopathies suggesting a role for these genes in cardiovascular pathology in the general population. We show that polygenic predisposition to PR interval duration is an endophenotype for cardiovascular disease, including distal conduction disease, AF, and atrioventricular pre-excitation. These findings advance our understanding of the polygenic basis of cardiac conduction, and the genetic relationship between PR interval duration and cardiovascular disease.
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http://dx.doi.org/10.1038/s41467-020-15706-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7242331PMC
May 2020

Predicted loss and gain of function mutations in ACO1 are associated with erythropoiesis.

Commun Biol 2020 04 23;3(1):189. Epub 2020 Apr 23.

deCODE genetics/Amgen Inc., Reykjavik, Iceland.

Hemoglobin is the essential oxygen-carrying molecule in humans and is regulated by cellular iron and oxygen sensing mechanisms. To search for novel variants associated with hemoglobin concentration, we performed genome-wide association studies of hemoglobin concentration using a combined set of 684,122 individuals from Iceland and the UK. Notably, we found seven novel variants, six rare coding and one common, at the ACO1 locus associating with either decreased or increased hemoglobin concentration. Of these variants, the missense Cys506Ser and the stop-gained Lys334Ter mutations are specific to eight and ten generation pedigrees, respectively, and have the two largest effects in the study (Effect = -1.61 SD, CI = [-1.98, -1.35]; Effect = 0.63 SD, CI = [0.36, 0.91]). We also find Cys506Ser to associate with increased risk of persistent anemia (OR = 17.1, P = 2 × 10). The strong bidirectional effects seen in this study implicate ACO1, a known iron sensing molecule, as a major homeostatic regulator of hemoglobin concentration.
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http://dx.doi.org/10.1038/s42003-020-0921-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7181819PMC
April 2020

Spread of SARS-CoV-2 in the Icelandic Population.

N Engl J Med 2020 06 14;382(24):2302-2315. Epub 2020 Apr 14.

From deCODE Genetics-Amgen (D.F.G., A.H., H.J., O.T.M., P.M., G.L.N., J.S., A.S., P.S., A.B.A., B.E., R.F., E.E.G., G.G., K.R.G., A.G., H.H., B.O.J., A.J., F.J., T.K., D.N.M., L.R., G. Sveinbjornsson, K.E.S., E.A.T., B.T., G.M., I.J., U.T., K.S.), the School of Engineering and Natural Sciences (D.F.G., P.M.), the Department of Anthropology (A.H.), the Faculty of Medicine, School of Health Sciences (A.L., I.J., K.G.K., U.T., K.S.), and the BioMedical Center of the University of Iceland (K.G.K.), University of Iceland, the Department of Clinical Microbiology, Landspitali-National University Hospital (O.S.G., T.R.G., M.S., A.L., K.G.K.) and the Directorate of Health (K.S.J., G. Sigmundsdottir, A.D.M., T.G.) - all in Reykjavik, Iceland.

Background: During the current worldwide pandemic, coronavirus disease 2019 (Covid-19) was first diagnosed in Iceland at the end of February. However, data are limited on how SARS-CoV-2, the virus that causes Covid-19, enters and spreads in a population.

Methods: We targeted testing to persons living in Iceland who were at high risk for infection (mainly those who were symptomatic, had recently traveled to high-risk countries, or had contact with infected persons). We also carried out population screening using two strategies: issuing an open invitation to 10,797 persons and sending random invitations to 2283 persons. We sequenced SARS-CoV-2 from 643 samples.

Results: As of April 4, a total of 1221 of 9199 persons (13.3%) who were recruited for targeted testing had positive results for infection with SARS-CoV-2. Of those tested in the general population, 87 (0.8%) in the open-invitation screening and 13 (0.6%) in the random-population screening tested positive for the virus. In total, 6% of the population was screened. Most persons in the targeted-testing group who received positive tests early in the study had recently traveled internationally, in contrast to those who tested positive later in the study. Children under 10 years of age were less likely to receive a positive result than were persons 10 years of age or older, with percentages of 6.7% and 13.7%, respectively, for targeted testing; in the population screening, no child under 10 years of age had a positive result, as compared with 0.8% of those 10 years of age or older. Fewer females than males received positive results both in targeted testing (11.0% vs. 16.7%) and in population screening (0.6% vs. 0.9%). The haplotypes of the sequenced SARS-CoV-2 viruses were diverse and changed over time. The percentage of infected participants that was determined through population screening remained stable for the 20-day duration of screening.

Conclusions: In a population-based study in Iceland, children under 10 years of age and females had a lower incidence of SARS-CoV-2 infection than adolescents or adults and males. The proportion of infected persons identified through population screening did not change substantially during the screening period, which was consistent with a beneficial effect of containment efforts. (Funded by deCODE Genetics-Amgen.).
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http://dx.doi.org/10.1056/NEJMoa2006100DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7175425PMC
June 2020

Genome-wide association identifies seven loci for pelvic organ prolapse in Iceland and the UK Biobank.

Commun Biol 2020 03 17;3(1):129. Epub 2020 Mar 17.

deCODE Genetics/Amgen, Sturlugata 8, 101, Reykjavik, Iceland.

Pelvic organ prolapse (POP) is a downward descent of one or more of the pelvic organs, resulting in a protrusion of the vaginal wall and/or uterus. We performed a genome-wide association study of POP using data from Iceland and the UK Biobank, a total of 15,010 cases with hospital-based diagnosis code and 340,734 female controls, and found eight sequence variants at seven loci associating with POP (P < 5 × 10); seven common (minor allele frequency >5%) and one with minor allele frequency of 4.87%. Some of the variants associating with POP also associated with traits of similar pathophysiology. Of these, rs3820282, which may alter the estrogen-based regulation of WNT4, also associates with leiomyoma of uterus, gestational duration and endometriosis. Rs3791675 at EFEMP1, a gene involved in connective tissue homeostasis, also associates with hernias and carpal tunnel syndrome. Our results highlight the role of connective tissue metabolism and estrogen exposure in the etiology of POP.
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http://dx.doi.org/10.1038/s42003-020-0857-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7078216PMC
March 2020
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