| 1. |
- Milani, Lili, 1981-
(författare)
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Gene Expression in Cancer Cells : Detection of Splice Variants, Allele-specific Expression and DNA Methylation
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The human genome sequencing project has provided a wealth of information on sequence variation between individuals. The surprisingly low number of genes in the human genome is compensated for by a complex regulation of gene expression. New methods are now being developed for the discovery and analysis of the regulatory regions of the genome to elucidate factors that affect both normal and disease-associated human genetic variation. In parallel with identification of DNA sequence variation, efforts are being made to unravel the next layer of information - epigenetic modifications of the genome. The studies in this thesis describe the application of methods for genotyping single nucleotide polymorphisms (SNPs) in DNA for the analysis of gene transcripts in cancer cells. We performed quantitative analysis of splice variants and screened for allele-specific gene expression (ASE) in cancer cells using the tag-microarray based minisequencing system. This analysis revealed transcript isoforms that were differentially spliced in leukemia cell lines and normal endothelial cell lines. We detected wide-spread allele-specific gene expression in cancer cells that were sensitive or resistant to anti-cancer drugs. In regulatory regions of the genes with ASE we identified putative regulatory SNPs. Using technology developed for large-scale SNP genotyping, we screened for ASE in an internationally unique collection of childhood acute lymphoblastic leukemia (ALL) samples. Analysis of DNA methylation in promoter regions of genes displaying ASE revealed genes, whose expression is regulated by allele-specific DNA methylation. For a subset of these genes we found a correlation between DNA methylation levels and probability of disease-free survival in ALL patients with different chromosomal aberrations. The methylation patterns that we identified constitute excellent candidate markers for subtyping of ALL patients and for stratification of ALL patients based on their probability of disease-free survival and response to drug treatment. The results of this study have increased our understanding of epigenetic changes in ALL cells and will hopefully help to design better treatment plans for the patients to avoid over-treatment and unnecessary side effects.
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| 2. |
- Parmar, Priyanka, et al.
(författare)
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Association of maternal prenatal smoking GFI1-locus and cardiometabolic phenotypes in 18,212 adults
- 2018
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Ingår i: EBioMedicine. - : Elsevier BV. - 2352-3964. ; 38, s. 206-216
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Tidskriftsartikel (refereegranskat)abstract
- Background: DNA methylation at the GFI1-locus has been repeatedly associated with exposure to smoking from the foetal period onwards. We explored whether DNA methylation may be a mechanism that links exposure to maternal prenatal smoking with offspring's adult cardio-metabolic health. Methods: We meta-analysed the association between DNA methylation at GFI1-locus with maternal prenatal smoking, adult own smoking, and cardio-metabolic phenotypes in 22 population-based studies from Europe, Australia, and USA (n= 18,212). DNA methylation at the GFI1-locus was measured in whole-blood. Multivariable regression models were fitted to examine its association with exposure to prenatal and own adult smoking. DNA methylation levels were analysed in relation to body mass index (BMI), waist circumference (WC), fasting glucose (FG), high-density lipoprotein cholesterol (HDL-C), triglycerides (TG), diastolic, and systolic blood pressure (BP). Findings: Lower DNA methylation at three out of eight GFI1-CpGs was associated with exposure to maternal prenatal smoking, whereas, all eight CpGs were associated with adult own smoking. Lower DNA methylation at cg14179389, the strongest maternal prenatal smoking locus, was associated with increased WC and BP when adjusted for sex, age, and adult smoking with Bonferroni-corrected P < 0.012. In contrast, lower DNA methylation at cg09935388, the strongest adult own smoking locus, was associated with decreased BMI, WC, and BP (adjusted 1 x 10(-7) < P < 0.01). Similarly, lower DNA methylation at cg12876356, cg18316974, cg09662411, and cg18146737 was associated with decreased BMI and WC (5 x 10(-8) < P < 0.001). Lower DNA methylation at all the CpGs was consistently associated with higher TG levels. Interpretation: Epigenetic changes at the GFI1 were linked to smoking exposure in-utero/in-adulthood and robustly associated with cardio-metabolic risk factors. Fund: European Union's Horizon 2020 research and innovation programme under grant agreement no. 633595 DynaHEALTH.
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| 3. |
- Reisberg, Sulev, et al.
(författare)
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Translating genotype data of 44,000 biobank participants into clinical pharmacogenetic recommendations : challenges and solutions
- 2019
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Ingår i: Genetics in Medicine. - : NATURE PUBLISHING GROUP. - 1098-3600 .- 1530-0366. ; 21:6, s. 1345-1354
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: Biomedical databases combining electronic medical records and phenotypic and genomic data constitute a powerful resource for the personalization of treatment. To leverage the wealth of information provided, algorithms are required that systematically translate the contained information into treatment recommendations based on existing genotype-phenotype associations. Methods: We developed and tested algorithms for translation of preexisting genotype data of over 44,000 participants of the Estonian biobank into pharmacogenetic recommendations. We compared the results obtained by genome sequencing, exome sequencing, and genotyping using microarrays, and evaluated the impact of pharmacogenetic reporting based on drug prescription statistics in the Nordic countries and Estonia. Results: Our most striking result was that the performance of genotyping arrays is similar to that of genome sequencing, whereas exome sequencing is not suitable for pharmacogenetic predictions. Interestingly, 99.8% of all assessed individuals had a genotype associated with increased risks to at least one medication, and thereby the implementation of pharmacogenetic recommendations based on genotyping affects at least 50 daily drug doses per 1000 inhabitants. Conclusion: We find that microarrays are a cost-effective solution for creating preemptive pharmacogenetic reports, and with slight modifications, existing databases can be applied for automated pharmacogenetic decision support for clinicians.
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| 4. |
- Tasa, Tonis, et al.
(författare)
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Genetic variation in the Estonian population : pharmacogenomics study of adverse drug effects using electronic health records
- 2019
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Ingår i: European Journal of Human Genetics. - : NATURE PUBLISHING GROUP. - 1018-4813 .- 1476-5438. ; 27:3, s. 442-454
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Tidskriftsartikel (refereegranskat)abstract
- Pharmacogenomics aims to tailor pharmacological treatment to each individual by considering associations between genetic polymorphisms and adverse drug effects (ADEs). With technological advances, pharmacogenomic research has evolved from candidate gene analyses to genome-wide association studies. Here, we integrate deep whole-genome sequencing (WGS) information with drug prescription and ADE data from Estonian electronic health record (EHR) databases to evaluate genome- and pharmacome-wide associations on an unprecedented scale. We leveraged WGS data of 2240 Estonian Biobank participants and imputed all single-nucleotide variants (SNVs) with allele counts over 2 for 13,986 genotyped participants. Overall, we identified 41 (10 novel) loss-of-function and 567 (134 novel) missense variants in 64 very important pharmacogenes. The majority of the detected variants were very rare with frequencies below 0.05%, and 6 of the novel lossof-function and 99 of the missense variants were only detected as single alleles (allele count = 1). We also validated documented pharmacogenetic associations and detected new independent variants in known gene-drug pairs. Specifically, we found that CTNNA3 was associated with myositis and myopathies among individuals taking nonsteroidal anti-inflammatory oxicams and replicated this finding in an extended cohort of 706 individuals. These findings illustrate that population-based WGS-coupled EHRs are a useful tool for biomarker discovery.
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| 5. |
- Zhou, Yitian, et al.
(författare)
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Global genetic diversity of human apolipoproteins and effects on cardiovascular disease risk
- 2018
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Ingår i: Journal of Lipid Research. - : AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC. - 0022-2275 .- 1539-7262. ; 59:10, s. 1987-2000
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Tidskriftsartikel (refereegranskat)abstract
- Abnormal plasma apolipoprotein levels are consistently implicated in CVD risk. Although 30% to 60% of their interindividual variability is genetic, common genetic variants explain only 10% to 20% of these differences. Rare genetic variants may be major sources of the missing heritability, yet quantitative evaluations of their contribution to phenotypic variability are lacking. Here, we analyzed whole-genome and whole-exome sequencing data from 138,632 individuals across seven major human populations to present a systematic overview of genetic apolipoprotein variability. We provide population-specific frequencies of 38 clinically important apolipoprotein alleles and identify further 6,875 genetic variants, 33% of which are novel and 98.7% of which are rare with minor allele frequencies <1%. We predicted the functional impact of rare variants and found that their relative importance differed drastically between genes and among ethnicities. Importantly, we validated the clinical relevance of multiple variants with predicted effects by leveraging association data from the CARDIoGRAM (Coronary Artery Disease Genomewide Replication and Meta-analysis) and Global Lipids Genetics consortia. Overall, we provide a consolidated overview of population-specific apolipoprotein genetics as a valuable data resource for scientists and clinicians, estimate the importance of rare genetic variants for the missing heritability of apolipoprotein-associated disease traits, and pinpoint multiple novel apolipoprotein variants with putative population-specific impacts on serum lipid levels.
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