| 1. |
- Henmyr, Viktor, et al.
(författare)
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Characterization of genetic variation in TLR8 in relation to allergic rhinitis
- 2015
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Ingår i: Allergy. European Journal of Allergy and Clinical Immunology. - : Wiley-Blackwell. - 0105-4538 .- 1398-9995.
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: A previous investigation of all 10 TLR-genes for associations with allergic rhinitis (AR) detected a number of significant SNPs in the TLR8 locus. The associations indicated that an accumulation of rare variants could explain the signal. The present study therefore searches for rare variants in the TLR8 region and also investigates the reproducibility of previous SNP associations.METHODS: The TLR8 gene was re-sequenced in 288 AR patients from Malmö and the data was compared with publically available data. Seven previously AR-associated SNPs from TLR8 were analyzed for AR-associations in 422 AR patients and 859 controls from the BAMSE cohort. The associations detected in present and previous studies were compared.RESULTS: Sequencing detected 13 polymorphisms (3 promotor, 10 coding) among 288 AR patients. Four of the coding polymorphisms were rare (MAF <1%) and three of those were novel. Two coding polymorphisms were benign missense mutations and the rest were synonymous. Comparison with 1000Genomes and Exome Aggregation Consortium data revealed no accumulation of rare variants in the AR cases. The AR-association tests made using the BAMSE cohort yielded 5 P-values < 0.05. Tests of IgE-levels yielded 4 significant SNP associations to birch pollen. Comparing results between different populations revealed opposing risk alleles, different gender effects and response to different allergens in the different populations.CONCLUSIONS: Rare variants in TLR8 are not associated with AR. Comparison of present and previous association studies reveal contradictory results for common variants. Thus, no associations exist between genetic variation in TLR8 and AR. This article is protected by copyright. All rights reserved.
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| 2. |
- Nilsson, Daniel, et al.
(författare)
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Poor reproducibility of allergic rhinitis SNP associations
- 2013
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 8:1, s. e53975-
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Tidskriftsartikel (refereegranskat)abstract
- Replication of reported associations is crucial to the investigation of complex disease. More than 100 SNPs have previously been reported as associated with allergic rhinitis (AR), but few of these have been replicated successfully. To investigate the general reproducibility of reported AR-associations in candidate gene studies, one Swedish (352 AR-cases, 709 controls) and one Singapore Chinese population (948 AR-cases, 580 controls) were analyzed using 49 AR-associated SNPs. The overall pattern of P-values indicated that very few of the investigated SNPs were associated with AR. Given published odds ratios (ORs) most SNPs showed high power to detect an association, but no correlations were found between the ORs of the two study populations or with published ORs. None of the association signals were in common to the two genome-wide association studies published in AR, indicating that the associations represent false positives or have much lower effect-sizes than reported.
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| 3. |
- Jakobsson, Mattias, et al.
(författare)
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Evolution of chloroplast mononucleotide microsatellites in Arabidopsis thaliana
- 2007
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Ingår i: Theoretical and Applied Genetics. - : Springer. - 0040-5752 .- 1432-2242. - 0040-5752 ; 114:2, s. 223-235
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Tidskriftsartikel (refereegranskat)abstract
- The level of variation and the mutation rate were investigated in an empirical study of 244 chloroplast microsatellites in 15 accessions of Arabidopsis thaliana. In contrast to SNP variation, microsatellite variation in the chloroplast was found to be common, although less common than microsatellite variation in the nucleus. No microsatellite variation was found in coding regions of the chloroplast. To evaluate different models of microsatellite evolution as possible explanations for the observed pattern of variation, the length distribution of microsatellites in the published DNA sequence of the A. thaliana chloroplast was subsequently used. By combining information from these two analyses we found that the mode of evolution of the chloroplast mononucleotide microsatellites was best described by a linear relation between repeat length and mutation rate, when the repeat lengths exceeded about 7 bp. This model can readily predict the variation observed in non-coding chloroplast DNA. It was found that the number of uninterrupted repeat units had a large impact on the level of chloroplast microsatellite variation. No other factors investigated-such as the position of a locus within the chromosome, or imperfect repeats-appeared to affect the variability of chloroplast microsatellites. By fitting the slippage models to the Genbank sequence of chromosome 1, we show that the difference between microsatellite variation in the nucleus and the chloroplast is largely due to differences in slippage rate.
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| 4. |
- Manderstedt, Eric, et al.
(författare)
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Detection of F8 int22h inversions using digital droplet PCR and mile-post assays
- 2020
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Ingår i: Journal of Thrombosis and Haemostasis. - : Wiley-Blackwell. - 1538-7933 .- 1538-7836. ; 8:5, s. 1039-1049
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Inversions involving intron 22 (Inv22) of F8 are detected in approximately 45% of all severe hemophilia A patients. Diagnosis is complicated by the large size of the ~9.5 kb int22h repeated sequence which generates the inversions. Methods such as long-range PCR and inverse-shifting PCR are currently used diagnostically, but suffer from low PCR efficiencies and are difficult to standardize.OBJECTIVES: To design and validate a sensitive and robust assay for the detection of F8 int22h inversions.METHODS: Digital droplet PCR using mile-post assays was used to investigate archival DNA samples.RESULTS: The detection of linkage as a function of physical distance between loci was investigated using an anchor locus and mile-post loci located at 1, 6, 12 and 15 kb distances from the anchor locus. The proportion of linked molecules decreased with increasing distance between loci and showed 30-40% linked molecules for loci 12-15 kb apart. Mile-post assays specific for wild type and Inv22 type 1 and 2 chromosomes were then designed and optimized. All three assays showed high specificities and sensitivities, with coefficients of variation < 5% for all assays. Analysis of 106 patients and 20 carrier mothers showed complete concordance with previously known mutation status. The analysis demonstrated the robustness of the assays versus input DNA concentration (6 ng and higher) and level of fragmentation.CONCLUSIONS: Digital droplet PCR and mile-post assays can be used to detect F8 int22h inversions. The assay systems are technically simple to perform, highly efficient and robust.
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| 5. |
- Säll, T., et al.
(författare)
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Chloroplast DNA indicates a single origin of the allotetraploid Arabidopsis suecica
- 2003
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Ingår i: Journal of Evolutionary Biology. - : John Wiley & Sons Inc.. - 1010-061X .- 1420-9101. ; 16:5, s. 1019-1029
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Tidskriftsartikel (refereegranskat)abstract
- DNA sequencing was performed on up to 12 chloroplast DNA regions [giving a total of 4288 base pairs (bp) in length] from the allopolyploid Arabidopsis suecica (48 accessions) and its two parental species, A. thaliana (25 accessions) and A. arenosa (seven accessions). Arabidopsis suecica was identical to A. thaliana at all 93 sites where A. thaliana and A. arenosa differed, thus showing that A. thaliana is the maternal parent of A. suecica. Under the assumption that A. thaliana and A. arenosa separated 5 million years ago, we estimated a substitution rate of 2.9 x 10(-9) per site per year in noncoding single copy sequence. Within A. thaliana we found 12 substitution (single bp) and eight insertion/deletion (indel) polymorphisms, separating the 25 accessions into 15 haplotypes. Eight of the A. thaliana accessions from central Sweden formed one cluster, which was separated from a cluster consisting of central European and extreme southern Swedish accessions. This latter cluster also included the A. suecica accessions, which were all identical except for one 5 bp indel. We interpret this low level of variation as a strong indication that A. suecica effectively has a single origin, which we dated at 20 000 years ago or more.
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| 6. |
- Halldén, Christer, 1957-, et al.
(författare)
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Investigation of disease-associated factors in haemophilia A patients without detectable mutations
- 2012
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Ingår i: Haemophilia. - : Blackwell. - 1351-8216 .- 1365-2516. ; 18:3, s. e132-e137
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Tidskriftsartikel (refereegranskat)abstract
- To investigate disease causing mechanism in haemophilia A patients without detectable mutation. Screening for F8 mutations in 307 haemophilia A patients using: re-sequencing and inversion PCR, reverse transcription (RT-PCR) of mRNA, MLPA analysis, haplotyping using SNP and microsatellite markers. No F8 mutations were detected in 9 of the 307 patients (2.9%) using re-sequencing and inversion PCR. MLPA analysis detected duplication in exon 6 in one patient and RT-PCR showed no products for different regions of mRNA in four other patients, indicating failed transcription. No obvious associations were observed between the phenotypes of the nine patients, their F8 haplotypes and the putative mutations detected. The mutation-positive patients carrying the same haplotypes as the mutation-negative patients show a multitude of different mutations, emphasizing the lack of associations at the haplotype level. VWF mutation screening and factor V measurements ruled out type 2N VWD and combined factor V and VIII deficiency respectively. To further investigate a possible role for FVIII interacting factors the haplotypes/diplotypes of F2, F9, F10 and VWF were compared. The nine patients had no specific haplotype/diplotype combination in common that can explain disease. Duplications and faulty transcription contribute to the mutational spectrum of haemophilia A patients where conventional mutation screening fail to identify mutations.
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| 7. |
- Halldén, Christer, et al.
(författare)
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Origin of Swedish hemophilia A mutations
- 2012
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Ingår i: Journal of Thrombosis and Haemostasis. - : Elsevier BV. - 1538-7933 .- 1538-7836. ; 10:12, s. 2503-2511
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Tidskriftsartikel (refereegranskat)abstract
- Background: Hemophilia A (HA) has a high level of variation within the disease class, with more than 1000 mutations being listed in the HAMSTeRS database. At the same time a number of F8 mutations are present in specific populations at high frequencies. Objectives: The simultaneous presence of large numbers of rare mutations and a small number of high-frequency mutations raises questions about the origins of HA mutations. The present study was aimed at describing the origins of HA mutations in the complete Swedish population. The primary issue was to determine what proportion of identical mutations are identical by descent (IBD) and what proportion are attributable to recurrent mutation events. The age of IBD mutations was also determined. Patients/Methods: In Sweden, the care of HA is centralized, and the Swedish HA population consists of 750 patients from > 300 families (35% severe, 15% moderate, and 50% mild). Identical haplotypes were defined by single-nucleotide polymorphism and microsatellite haplotyping, and the ages of the mutations were estimated with estiage. Results: Among 212 presumably unrelated patients with substitution mutations, 97 (46%) had mutations in common with other patients. Haplotyping of the 97 patients showed that 47 had IBD mutations (22%) with estimated ages of between two and 35 generations. The frequency of mild disease increased with an increasing number of patients sharing the mutations. Conclusions: A majority of the IBD mutations are mild and have age estimates of a few hundred years, but some could date back to the Middle Ages.
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| 8. |
- Halldén, Christer, et al.
(författare)
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Origin of Swedish hemophilia B mutations
- 2013
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Ingår i: Journal of Thrombosis and Haemostasis. - : Elsevier BV. - 1538-7933 .- 1538-7836. ; 11:11, s. 2001-2008
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Tidskriftsartikel (refereegranskat)abstract
- Background More than 1100 mutations that cause hemophilia B (HB) have been identified. At the same time, specific F9 mutations are present at high frequencies in certain populations, which raise questions about the origin of HB mutations. ObjectivesTo describe the mutation spectrum of all HB families in Sweden and investigate if mutations appearing in several families are due to independent recurrent mutations (RMs) or to a common mutation event (i.e. are identical by descent (IBD)). Patients/MethodsThe registered Swedish HB population consists of patients from 86 families. Mutations were identified by resequencing and identical haplotypes were defined using 74 markers and a control population of 285 individuals. The ages of IBD mutations were estimated using ESTIAGE. ResultsOut of 77 presumably unrelated patients with substitution mutations, 47 patients (61%) had mutations in common with other patients. Haplotyping of the 47 patients showed that 24 patients had IBD mutations (51%) with estimated ages of between two and 23 generations. A majority of these patients had mild disease. Eight of the 15 mutations observed in more than one family were C>T transitions in CpG sites and all eight were RMs. ConclusionsThe association of IBD mutations with a mild phenotype is similar to what has been previously observed in hemophilia A. Noteworthy features of the mutations that are common to more than one family are the equal proportions of patients with RM and IBD mutations and the correlation between the occurrence of RMs and C>T transitions at CpG sites.
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| 9. |
- Henmyr, Viktor, et al.
(författare)
-
Characterization of genetic variation in TLR8 in relation to allergic rhinitis
- 2015
-
Ingår i: Allergy. European Journal of Allergy and Clinical Immunology. - : Wiley. - 0105-4538 .- 1398-9995.
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: A previous investigation of all 10 TLR-genes for associations with allergic rhinitis (AR) detected a number of significant SNPs in the TLR8 locus. The associations indicated that an accumulation of rare variants could explain the signal. The present study therefore searches for rare variants in the TLR8 region and also investigates the reproducibility of previous SNP associations. METHODS: The TLR8 gene was re-sequenced in 288 AR patients from Malmö and the data was compared with publically available data. Seven previously AR-associated SNPs from TLR8 were analyzed for AR-associations in 422 AR patients and 859 controls from the BAMSE cohort. The associations detected in present and previous studies were compared. RESULTS: Sequencing detected 13 polymorphisms (3 promotor, 10 coding) among 288 AR patients. Four of the coding polymorphisms were rare (MAF <1%) and three of those were novel. Two coding polymorphisms were benign missense mutations and the rest were synonymous. Comparison with 1000Genomes and Exome Aggregation Consortium data revealed no accumulation of rare variants in the AR cases. The AR-association tests made using the BAMSE cohort yielded 5 P-values < 0.05. Tests of IgE-levels yielded 4 significant SNP associations to birch pollen. Comparing results between different populations revealed opposing risk alleles, different gender effects and response to different allergens in the different populations. CONCLUSIONS: Rare variants in TLR8 are not associated with AR. Comparison of present and previous association studies reveal contradictory results for common variants. Thus, no associations exist between genetic variation in TLR8 and AR. This article is protected by copyright. All rights reserved.
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| 10. |
- Henmyr, Viktor, et al.
(författare)
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Chronic rhinosinusitis patients show accumulation of genetic variants in PARS2
- 2016
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Ingår i: PLoS ONE. - : Public Library of Science. - 1932-6203. ; 11:6
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Tidskriftsartikel (refereegranskat)abstract
- Genetic studies of chronic rhinosinusitis (CRS) have identified a total of 53 CRS-associated SNPs that were subsequently evaluated for their reproducibility in a recent study. The rs2873551 SNP in linkage disequilibrium with PARS2 showed the strongest association signal. The present study aims to comprehensively screen for rare variants in PARS2 and evaluate for accumulation of such variants in CRS-patients. Sanger sequencing and long-range PCR were used to screen for rare variants in the putative promoter region and coding sequence of 310 CRS-patients and a total of 21 variants were detected. The mutation spectrum was then compared with data from European populations of the 1000Genomes project (EUR) and the Exome Aggregation Consortium (ExAC). The CRS population showed a significant surplus of low-frequency variants compared with ExAC data. Haplotype analysis of the region showed a significant excess of rare haplotypes in the CRS population compared to the EUR population. Two missense mutations were also genotyped in the 310 CRS patients and 372 CRS-negative controls, but no associations with the disease were found. This is the first re-sequencing study in CRS research and also the first study to show an association of rare variants with the disease.
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