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- Lethagen, Stefan, et al.
(author)
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Distribution of von Willebrand factor levels in young women with and without bleeding symptoms : influence of ABO blood group and promoter haplotypes
- 2008
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In: Thrombosis and Haemostasis. - 0340-6245. ; 99:6, s. 1013-1018
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Journal article (peer-reviewed)abstract
- The normal distribution of von Willebrand factor (VWF) levels is wide. Low levels are associated with bleeding symptoms and von Willebrand disease (VWD). We have recently described a high prevalence of bleeding symptoms in a whole age group of young females (n = 1,019) from Malmo, Sweden. It was the objective of the present study to evaluate the distribution of VWF levels in young females with or without bleeding symptoms in this population, and the influence of ABO blood group and promoter haplotypes on VWF levels and to identify a possible increased prevalence of VWD in females with bleeding symptoms. A random selection of the female age group (n = 246), into a study group (n = 176) with, and a control group (n = 70) without bleeding symptoms, was evaluated. Eighteen girls had VWF:RCo below the reference range, of which 17 belonged to the study group (17/176, 9.7%), and one to the control group (1/70, 1.4%) (p = 0.017). Blood group O was found in 14/18 girls with low VWF:RCo. There was a highly significant correlation between VWF:RCo and blood group O and non-O genotypes. Two common VWF promoter haplotypes did not contribute to the VWF:RCo variation. VWF levels did not correlate with time during menstrual cycle, or the use of oral contraceptives. No case fulfilled the diagnostic criteria for VWD. In conclusion, low VWF:RCo was significantly more frequent in females with bleeding symptoms. However, we found no case fulfilling strict diagnostic criteria for VWD. The ABO blood group was a strong modifier, but VWF promoter haplotypes had no association to VWF levels in this population.
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9. |
- Lethagen, Stefan, et al.
(author)
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Distribution of von Willebrand factor levels in young women with and without bleeding symptoms. Influence of ABO blood group and promoter haplotypes
- 2008
-
In: Thrombosis and Haemostasis. - 0340-6245. ; 99:6, s. 1013-1018
-
Journal article (peer-reviewed)abstract
- The normal distribution of von Willebrand factor (VWF) levels is wide. Low levels are associated with bleeding symptoms and von Willebrand disease (VWD). We have recently described a high prevalence of bleeding symptoms in a whole age group of young females (n = 1,019) from Malmo, Sweden. It was the objective of the present study to evaluate the distribution of VWF levels in young females with or without bleeding symptoms in this population, and the influence of ABO blood group and promoter haplotypes on VWF levels and to identify a possible increased prevalence of VWD in females with bleeding symptoms. A random selection of the female age group (n = 246), into a study group (n = 176) with, and a control group (n = 70) without bleeding symptoms, was evaluated. Eighteen girls had VWF:RCo below the reference range, of which 17 belonged to the study group (17/176, 9.7%), and one to the control group (1/70, 1.4%) (p = 0.017). Blood group O was found in 14/18 girls with lowVWF:RCo. There was a highly significant correlation between VWF:RCo and blood group O and non-O genotypes. Two common VWF promoter haplotypes did not contribute to the VWF:RCo variation. VWF levels did not correlate with time during menstrual cycle, or the use of oral contraceptives. No case fulfilled the diagnostic criteria for VWD. In conclusion, low VWF:RCo was significantly more frequent in females with bleeding symptoms. However, we found no case fulfilling strict diagnostic criteria for VWD. The ABO blood group was a strong modifier, but VWF promoter haplotypes had no association to VWF levels in this population.
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- Mattson, Stefan
(author)
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Essays on structural equation modelling with applications of the basic univariate twin model
- 1998
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Doctoral thesis (other academic/artistic)abstract
- Structural equation models have proven useful for studies of genetic and environmental effects forvarious traits end the classical twin study has been considered as a powerful design for such studies. This thesis consist of five papers dealing with the analysis of structural equation models with applications of the basic univariate twin model.Monte Carlo simulation is a useful method for assessing the properties of an estimator for situations which are often found in real-world applications. In the first paper a method to generate data for simulation of structural equation models is presented.The second paper deals with the robustness of two commonly used estimators assuming the basic univariate twin model. The robustness is analysed from a theoretical point of view and through simulations.In the third paper it is shown how closed form expressions for a class of estimators can be derived assuming the basic univariate twin model. Expressions for robust standard errors and a robust test statistic for test of model fit are derived using these closed form expressions. A simulation study is presented where the properties of the robust standard errors and robust fit statistic are analysed for this model.The fourth paper considers Full Information Maximum Likelihood estimation of the basic univariate twin model when the observed trait is measured on an ordinal scale. Identification and estimation of the underlying mean and covariance structures as well as test of model fit are discussed. Numericalillustrations are presented.The fifth paper examines children liability to accidental injuries. This empirical study is based on a twin study and the method of estimation proposed in the fourth paper is applied.
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