| 1. |
- 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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| 2. |
- 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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| 3. |
- Halldén, Christer, 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. - : Wiley-Blackwell Publishing Ltd. - 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 deficiencyrespectively. 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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| 4. |
- Andiappan, Anand Kumar, et al.
(författare)
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Investigating highly replicated asthma genes as candidate genes for allergic rhinitis
- 2013
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Ingår i: BMC Medical Genetics. - : Springer Science and Business Media LLC. - 1471-2350. ; 14
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Tidskriftsartikel (refereegranskat)abstract
- Background: Asthma genetics has been extensively studied and many genes have been associated with the development or severity of this disease. In contrast, the genetic basis of allergic rhinitis (AR) has not been evaluated as extensively. It is well known that asthma is closely related with AR since a large proportion of individuals with asthma also present symptoms of AR, and patients with AR have a 5-6 fold increased risk of developing asthma. Thus, the relevance of asthma candidate genes as predisposing factors for AR is worth investigating. The present study was designed to investigate if SNPs in highly replicated asthma genes are associated with the occurrence of AR. Methods: A total of 192 SNPs from 21 asthma candidate genes reported to be associated with asthma in 6 or more unrelated studies were genotyped in a Swedish population with 246 AR patients and 431 controls. Genotypes for 429 SNPs from the same set of genes were also extracted from a Singapore Chinese genome-wide dataset which consisted of 456 AR cases and 486 controls. All SNPs were subsequently analyzed for association with AR and their influence on allergic sensitization to common allergens. Results: A limited number of potential associations were observed and the overall pattern of P-values corresponds well to the expectations in the absence of an effect. However, in the tests of allele effects in the Chinese population the number of significant P-values exceeds the expectations. The strongest signals were found for SNPs in NPSR1 and CTLA4. In these genes, a total of nine SNPs showed P-values <0.001 with corresponding Q-values <0.05. In the NPSR1 gene some P-values were lower than the Bonferroni correction level. Reanalysis after elimination of all patients with asthmatic symptoms excluded asthma as a confounding factor in our results. Weaker indications were found for IL13 and GSTP1 with respect to sensitization to birch pollen in the Swedish population. Conclusions: Genetic variation in the majority of the highly replicated asthma genes were not associated to AR in our populations which suggest that asthma and AR could have less in common than previously anticipated. However, NPSR1 and CTLA4 can be genetic links between AR and asthma and associations of polymorphisms in NPSR1 with AR have not been reported previously.
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| 5. |
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| 6. |
- 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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| 7. |
- 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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| 8. |
- Hjerdin, A, et al.
(författare)
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Genetic Variation Among Wild and Cultivated Beets of the Section Beta as Revealed by RFLP Analysis
- 1994
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Ingår i: Journal of sugarbeet research. - 0899-1502. ; 31:1&2, s. 59-67
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Tidskriftsartikel (refereegranskat)abstract
- The level of genetic variation detected among 7 sugar beet and 4 fodder beet breeding lines was compared to the variation found among 21 accessions of wild beets of the section Beta. RFLP analysis used a set of 32 sugar beet DNA sequences as probes to score a total of 351 bands over all accessions. The band data was used to calculate genetic distances between all pairs of accessions. The distance estimates were subsequently used in a cluster analysis to produce a dendrogram of genetic distances. The analysis unambiguously defined all accessions and clearly defined a fodder beet cluster within the sugar beet cluster. The cultivated beets were all separated from the wild beets. The sugar beet breeding lines showed a considerable amount of genetic variation, comparable with the level of variation detected among the wild beet accessions.
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| 9. |
- Kraft, T., et al.
(författare)
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Positive correlation between recombination rates and levels of genetic variation in natural populations of sea beet (Beta vulgaris subsp. maritima)
- 1998
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Ingår i: Genetics. - 0016-6731 .- 1943-2631. ; 150:3, s. 1239-1244
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Tidskriftsartikel (refereegranskat)abstract
- The relation between the level of genetic variation and the rate of recombination per physical unit was investigated in sea beet (Beta vulgaris subsp. maritima). The rate of recombination per physical unit was estimated indirectly through marker density in an RFLP linkage map of sugar beet. From this map, we also selected RFLP markers covering two of the nine chromosomes in Beta. The markers were used to estimate the level of genetic variation in three populations of sea beet, two from Italy and one from England. Two estimates of genetic variation were employed, one based on the number of alleles in the sample and the other on heterozygosity. A statistically significant positive correlation was found between recombination rate and genetic variation. Several theoretical explanations for this are discussed, background selection being one. A correlation similar to this has been observed previously in Drosophila, one that was higher than what we obtained for Beta. This is consistent with various biological differences between the two species.
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| 10. |
- Manderstedt, Eric, et al.
(författare)
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Detection of mosaics in hemophilia A by deep Ion Torrent sequencing and droplet digital PCR
- 2020
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Ingår i: Research and practice in thrombosis and haemostasis. - : Wiley. - 2475-0379. ; 4:7, s. 1121-1130
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Tidskriftsartikel (refereegranskat)abstract
- Background: The occurrence of mosaicism in hemophilia A (HA) has been investigated in several studies using different detection methods. Objectives: To characterize and compare the ability of AmpliSeq/Ion Torrent sequencing and droplet digital polymerase chain reaction (ddPCR) for mosaic detection in HA. Methods: Ion Torrent sequencing and ddPCR were used to analyze 20 healthy males and 16 mothers of sporadic HA patients. Results: An error-rate map over all coding positions and all positions reported as mutated in the F8-specific mutation database was produced. The sequencing produced a mean read depth of >1500X where >97% of positions were covered by >100 reads. Higher error frequencies were observed in positions with A or T as reference allele and in positions surrounded on both sides with C or G. Seventeen of 9319 positions had a mean substitution error frequency >1%. The ability to identify low-level mosaicism was determined primarily by read depth and error rate of each specific position. Limit of detection (LOD) was <1% for 97% of positions with substitutions and 90% of indel positions. The positions with LOD >1% require repeated testing and mononucleotide repeats with more than four repeat units need an alternative analysis strategy. Mosaicism was detected in 1 of 16 mothers and confirmed using ddPCR. Conclusions: Deep sequencing using an AmpliSeq/Ion Torrent strategy allows for simultaneous identification of disease-causing mutations in patients and mosaicism in mothers. ddPCR has high sensitivity but is hampered by the need for mutationspecific design.
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