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- Ghasimi, Soma, 1984-
(författare)
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Genotype-phenotype studies in brain tumors
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Meningioma and glioma are the most common primary brain tumors, but their etiologies are largely unknown. Although meningioma is usually benign, their intracranial location can lead to lethal consequences, and despite progress in surgery, radiotherapy, and chemotherapy the prognosis for patients with glioma remains poor. The only well-established environmental risk factor for meningioma and glioma is ionizing radiation. Evidence for inherited predisposition to meningioma and glioma is provided by a number of rare inherited syndromes where collectively these diseases account for only a small proportion of the twofold increased risk of brain tumors seen in first-degree relatives for meningioma and glioma patients. It is very possible that much of the excess familial risk is a consequence of co-inheritance of multiple low-risk genetic variations. With this in mind, the aims of the studies in this thesis were to discover genetic risk variants influencing the probability of acquiring the disease and to identify the association between risk variants on the tumor phenotype.To identify genetic variants influencing meningioma risk, a comprehensive tagging of the selected genes in a case-control study was performed. We identified nine risk variants inEGF, ERBB2, and LRIG2 genes. However, these findings could not be confirmed in another larger independent dataset. In addition, the study identified a correlation between LRIG2 protein expression and ER status when analyzed with different parameters. In a separate study with a larger sample of meningioma patients, the same correlation between LRIG2 and ER status was observed.To explore the potential association between reported germline risk variants and somatic genetic events, matched tumor and blood samples from glioma patients were analyzed by SNP array. The results identified correlations betweenEGFR gene variants and somatic aberrations within the EGFR locus and CDKN2A/B locus. To further study the relationship between germline risk variants and tumor phenotype, the same patient material was used and analyzed by three different techniques: SNP array, IHC, and FISH. The results revealed EGFR risk variants effecting copy number variation of the EGFR gene and the expression of the IDH1 and p53. Further comparison between different techniques such as SNP array and FISH analysis revealed the difficulty in achieving consistent results with different techniques.To summarize, the glioma studies show a link between genotype and phenotype where genetic risk variants in theEGFR gene were found to be associated with specific somatic aberrations. These associations are biologically interesting because EGFR is involved in multiple cellular processes. Additional studies of the direct functional role of these observations need to be conducted to elucidate the molecular mechanisms underlying the identified association between germline gene variants and somatic aberrations. For the meningioma studies, no significant risk variants influencing the disease were found but a correlation between LRIG2 and ER status was observed. This result suggests a potential role for the LRIG protein in the pathogenesis of meningioma, but more studies are needed to confirm this hypothesizes.
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- Luczynska, Anna, et al.
(författare)
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Plasma 25-hydroxyvitamin D concentration and lymphoma risk: results of the European Prospective Investigation into Cancer and Nutrition
- 2013
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Ingår i: American Journal of Clinical Nutrition. - Rockville Pike, Bethesda, MD, USA : Elsevier BV. - 1938-3207 .- 0002-9165. ; 98:3, s. 827-838
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Tidskriftsartikel (refereegranskat)abstract
- Background: The relation between vitamin D status and lymphoma risk is inconclusive. Objective: We examined the association between prediagnostic plasma 25-hydroxyvitamin D [25(OH)D] and lymphoid cancer risk. Design: We conducted a study nested within the European Prospective Investigation into Cancer and Nutrition cohort of 1127 lymphoma cases and 1127 matched controls with a mean follow-up time of 7.1 y. Conditional logistic regression was used to estimate multivariable-adjusted incidence rate ratios of lymphoma risk in relation to plasma 25(OH)D. Season-standardized and season-specific 25(OH)D quartiles were used. We also analyzed 25(OH)D as a continuous variable and used predefined cutoffs. Results: No statistically significant association between plasma 25(OH)D and overall lymphoid cancer risk was observed. A positive association for B-cell non-Hodgkin lymphoma was noted only in those with a diagnosis made during the first 2 y of follow-up (P-heterogeneity = 0.03), which suggests the possibility of reverse causality. Further analysis restricted to participants with >= 2y of follow-up time showed a significant association between 25(OH)D and chronic lymphocytic leukemia (CLL) (n = 161): adjusted incidence rate ratios were 0.40 (95% CI: 0.18, 0.90; P-trend = 0.05) and 0.31 (95% CI: 0.13, 0.76; P-trend = 0.03) for the top compared with the bottom season-standardized and season-specific quartiles, respectively. Data on dietary vitamin D intake provided further support for the observed association (incidence rate ratio: 0.33; 95% CI = 0.12, 0.89; P-trend = 0.006). Conclusions: Our findings do not support a protective role of high 25(OH)D concentration in lymphoid cancers overall. However, they suggest that higher concentrations of 25(OH)D are associated with a reduced risk of CLL.
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- Melin, Beatrice
(författare)
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Förebygga och behandla cancer
- 2013. - 1
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Ingår i: Cancerforskning på nya vägar. - Umeå : Umeå universitet. - 9789174598056 ; , s. 36-45
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Bokkapitel (populärvet., debatt m.m.)
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- Melin, Beatrice, et al.
(författare)
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Genetics in glioma : lessons learned from genome-wide association studies
- 2013
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Ingår i: Current Opinion in Neurology. - : Lippincott Williams & Wilkins. - 1350-7540 .- 1473-6551. ; 26:6, s. 688-692
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Forskningsöversikt (refereegranskat)abstract
- Purpose of review The purpose of this review is to describe the recent knowledge gathered from the identification of seven genomic regions that have been linked to the risk of developing malignant glioma. Recent findings The recent novel discoveries in fine mapping and genotype-phenotype studies will be highlighted. Through imputation and next-generation sequencing a novel genetic variant, rs55705857, with a strong association at 8q24 has been discovered and validated in two studies. This locus is specifically associated with IDH1-mutated and IDH2-mutated tumors and oligodendroglial tumors, albeit the specific mechanism of tumor development is not understood. The genetic variants associated with the risk of glioma in the EGFR gene have also been associated with specific somatic aberrations, including loss at the CDKN2A/B locus and allele specific loss of EGFR in the tumors. A specific TP53 low frequency variant has also been associated with glioma risk and validated in a separate data set. The genetic risk in the telomere regulating genes TERT and RTEL appear to be associated with higher grade tumors without IDH mutations. Summary The link of genetic loci to specific tumor subtypes may have relevance for understanding glioma biology, and for developing new diagnostic tools and targeted therapy for glioma.
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- Melin, Beatrice, et al.
(författare)
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Known glioma risk loci are associated with glioma with a family history of brain tumours : a case-control gene association study
- 2013
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Ingår i: International Journal of Cancer. - : Wiley. - 0020-7136 .- 1097-0215. ; 132:10, s. 2464-2468
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Tidskriftsartikel (refereegranskat)abstract
- Familial cancer can be used to leverage genetic association studies. Recent genome-wide association studies have reported independent associations between seven single nucleotide polymorphisms (SNPs) and risk of glioma. The aim of this study was to investigate whether glioma cases with a positive family history of brain tumours, defined as having at least one first- or second-degree relative with a history of brain tumour, are associated with known glioma risk loci. One thousand four hundred and thirty-one glioma cases and 2,868 cancer-free controls were identified from four casecontrol studies and two prospective cohorts from USA, Sweden and Denmark and genotyped for seven SNPs previously reported to be associated with glioma risk in casecontrol designed studies. Odds ratios were calculated by unconditional logistic regression. In analyses including glioma cases with a family history of brain tumours (n = 104) and control subjects free of glioma at baseline, three of seven SNPs were associated with glioma risk: rs2736100 (5p15.33, TERT), rs4977756 (9p21.3, CDKN2A-CDKN2B) and rs6010620 (20q13.33, RTEL1). After Bonferroni correction for multiple comparisons, only one marker was statistically significantly associated with glioma risk, rs6010620 (ORtrend for the minor (A) allele, 0.39; 95% CI: 0.250.61; Bonferroni adjusted ptrend, 1.7 x 104). In conclusion, as previously shown for glioma regardless of family history of brain tumours, rs6010620 (RTEL1) was associated with an increased risk of glioma when restricting to cases with family history of brain tumours. These findings require confirmation in further studies with a larger number of glioma cases with a family history of brain tumours.
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- Pettersson-Kymmer, Ulrika, et al.
(författare)
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Genome-wide association study meta-analysis identifies the SOAT1/AXDND1 locus to be associated with hip and forearm fracture risk
- 2013
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Ingår i: Bone Abstracts.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Hip and forearm fractures are the two clinically most important non-vertebral fractures. Twin studies have demonstrated a high heritability of these fractures and the heritable component of fracture risk is largely independent of BMD. To identify common genetic variants associated with hip and forearm fractures, we performed a genome-wide association study (GWAS ~ 2.5 million SNPs) meta-analysis of two large fracture data sets within the well-characterized UFO cohort (UFO-hip; 1014 hip fractures and 862 controls, and UFO-forearm; 1060 forearm fractures and 1055 controls). All fractures were confirmed through radiographic reports. Replication was performed in the Women’s Health Initiative (WHI) cohort (1845 hip fractures verified by medical records and 2120 controls). We identified one SNP within the SOAT1/AXDND1 locus (1q25.2) that was associated with fracture risk at genome wide significance (OR per allele=1.33; P=3.1×10−8) in the UFO discovery meta-analysis. This SNP was associated with fracture risk both in the WHI replication cohort (OR 1.16, P=2.1×10−3) and in the combined analyses comprising 7956 subjects (3919 cases and 4037 controls; OR=1.24, P=5.6×10−10). However, it was not associated with BMD or biochemical bone markers, suggesting that its association with fractures is BMD-independent. A genetic score (GS), including information from 63 SNPs earlier shown to be reproducibly associated with BMD, was significantly associated with both hip (P=7.9×10−4) and forearm (P=8.6×10−5) fractures. Models including both the SNP in the SOAT1/AXDND1 locus and the GS demonstrated that the impact of the SNP in the SOAT1/AXDND1 locus on fracture risk was independent of the BMD-associated GS. In summary, both a BMD-associated GS and a non-BMD associated genetic variant in the SOAT1/AXDND1 locus are associated with hip and forearm fractures.
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